foundry manual

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FOUNDRY MANUAL ir G Henderieckx Gietech BV JANUARY 2005 1 FOUNDRY ACTIVITY CHAPTER DESCRIPTION PAGE 1. GENERAL OVERVIEW 2 2. DESIGN OF CASTINGS 6 3. LOGISTICS 9 4. ENGINEERING 12 5. PURCHASING & SUBCONTRACTING 16 6. PATTERN 18 7. MOULDING 26 8. MELTING 35 9. FETTLING 46 10. HEAT TREATMENT 52 11. MACHINING & MARKING 60 12. SURFACE TREATMENT 61 13. QUALITY DEPARTMENT 65 14. REPAIR 68 15. SALES & MARKETING 72 16. SERIAL – FIRST PIECE QUALIFICATION 74 17. ENVIRONMENT 83 18. AUTHOR Menu

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Page 1: Foundry Manual

FOUNDRY MANUAL

ir G Henderieckx Gietech BV JANUARY 2005 1

FOUNDRY ACTIVITY CHAPTER DESCRIPTION PAGE

1. GENERAL OVERVIEW 2 2. DESIGN OF CASTINGS 6 3. LOGISTICS 9 4. ENGINEERING 12 5. PURCHASING & SUBCONTRACTING 16 6. PATTERN 18 7. MOULDING 26 8. MELTING 35 9. FETTLING 46 10. HEAT TREATMENT 52 11. MACHINING & MARKING 60 12. SURFACE TREATMENT 61 13. QUALITY DEPARTMENT 65 14. REPAIR 68 15. SALES & MARKETING 72 16. SERIAL – FIRST PIECE QUALIFICATION 74 17. ENVIRONMENT 83 18. AUTHOR

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Page 2: Foundry Manual

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GENERAL OVERVIEW

GENERAL OVERVIEW

1. Introduction 2. Process 3. Important features 4. Conclusion

1. Introduction

A foundry is the process (producing castings); split up in several smaller processes each performing part of the job. The result must be a casting, which is, conform to the requirements of the customer. The sub processes are related one to the other and each process has an influence on the next one (next step in the total process). So it can be said that each department is the supplier of another and the customer of the previous (according to the total process) one. Quality is the result of the performance of each group in the process. Department further in the total process, can sometimes correct an insufficient performance of a previous department, but only due to extra cost! The words "quality does not cost" are true in the sense that an insufficient quality level will increase the cost of the casting. But requiring a higher quality level will cost basically more compared to a lower level. Sub suppliers can do some of the sub processes and some items can be bought. Inspection is not only the job of the quality control department but also of each responsible of a group or department! Maintenance is considered as an integral part of the production. Financial, health and human resources department are not included in this text. They are not considered typical foundry activity, which means necessary to produce correct castings.

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2. PROCESS The process has three major steps, which are not all done one after another in time. Some of them are running simultaneous. The flow chart below is indicating all steps.

ORDER

CONTRACT

OFFER

FINAL INSPECTION

HEAT TREATMENT

SURFACE TREATMENT

SUBCONTRACT ING

PURCHASING

PATTERN

MOULDING

MELTING

FETTLING

Repair

Inspection plan

INSPECT ION

ORDER ADMINISTRATION

ENGINEERING

PRODUCTION

Repair

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The first step is the paperwork to be done after the entry of an order. The order will be compared with the offer and or contract. The selling department will check price. The order administration office will check all data concerning number, drawing and pattern number, material, specifications and all commercials items as shipment, payment… The planning, in accordance with the required time and the production will be set. If this job is done, the Quality Control office will set up the inspection plan concerning casting performance, taking in account the requirements from the order and the requirements due to the quality level of the foundry. The engineering department will decide about all items necessary for the production: 1. items to purchase 2. items to subcontract 3. work sheets for pattern shop, moulding and melting, heat treatment and fettling and shipment The second step is the production of the casting. This can involve the pattern production, surface treatment and will involve moulding and melting as well as fettling, heat treatment and shipment. Sometimes also heat treatment is subcontracted. It is very important that engineering will get all feed back about problems, non-conformities and defects. They need this information to modify the work sheets. Engineering will also list and supervise the equipment and tooling (especially the mould boxes). If there is a need they can ask for investing extra ones. The third step is the inspection and surveillance step, mostly done by the quality department. The inspection must be done as well by the head of each group and or department. The information from the order will establish an inspection plan, which is made by the quality department and will be made available to the engineering department. The required quality level as well as the foundry quality level requirements will have an influence on the pouring system risers and chills and sometimes on the work procedures. This inspection plan will set the "hold points" and "check points". This inspection is also present if there is repair to be done by a subcontractor. The sales & marketing department will be described at the end (Chapter 15). This department is the connection between the foundry and the market.

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3. IMPORTANT FEATURES The most important feature is the importance and responsibility of the engineering department. They have the highest influence on the cost and quality of the castings. Each instruction that does not lead to a performance equal to the required quality level or better, will add extra cost due to correcting, repairing or even scrapping the castings involved. Engineering must have the knowledge of materials, foundry techniques and requirements and standards. This knowledge must be supplemented by experience, brought in by the foundry workers and suppliers. The other important feature is the necessity of "discipline" of the production people and sub suppliers to act according to the work sheets and to report about problems to every one involved. This is the only way to avoid these problems in the future. To make their job easier it is preferred to have work sheets, included with pictures made from previous castings. Every one can understand a picture but not very one can understand and handle according to drawings and sketches. It is important to have also the pictures and or the history of work instruction leading to problems. All these pictures can be made available in a booklet or ask for on the intranet of the foundry. A foundry is a "learning community" which will gather information and experience and increasing the level of the group by sharing all this.

4. CONCLUSION Making castings is a "skill" which level is set by experience and knowledge and the degree of sharing and discussing it. The engineering department and the correct applying of the work instructions as well as the feed back of problems will set the quality level. The inspection is not only done by the quality department but also by every responsible of a group or department and at the end of ever one in the foundry. Being a process every department, performing part of the process, does influence the result concerning quality and cost. In the detailed descriptions of the departments, each sub process (including a flow chart) will be described in detail and the important features as well as the influences on the process will be discussed. Sales & Marketing will be described in Chapter 15. The difference between the FPQ-, SP- and CAQ-production will be described in Chapter 16. ================================================================ Menu

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Design of castings

DESIGN OF CASTINGS

1. Introduction 2. Flow chart 3. Features 4. Conclusion

1. Introduction Design starts from a product, which has to perform a function. This product consists of one or more parts, some of them being a casting. The castings have to comply with several requirements concerning assembling of the product, strength and ductility of the material and requirements concerning the service conditions. These requirements are completed with three other items to get the best product at the lowest "total cost". The first item is to find an (international) standard to refer to, meeting all requirements of the design or performing better. The second item is the machining cost, which will be influenced by the shape, type of machining and machinability of the material. The third concerns the castibility into the foundry. The more complex the shape is, the more problems there will be. The required mechanical properties must be met in the "representative" wall thickness. It must be considered that the dimensions, included the tolerance range, do meet the requirements of the design and to locate the material excess, due to pattern draft, in the best area. A casting with an incorrect or "not best" design will cause trouble concerning quality and delivery reliability and will have a too high cost. And this will last forever…

2. Flow chart There are two steps in the design of a casting. The first step is to set up the requirements concerning strength and ductility (shape and section and material related), service condition resistance (concerns corrosion, erosion…) and assembly requirements (dimensions and tolerances and process reliability). An inventory is made from these. All these items involve the "product" and are depending on the designer. No third party is involved up to now.

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The second step concerns third parties. First it is important to find an international standard, which does comply with the requirements. If no one is found, it is preferred to choose one with slightly higher (better for the design) values. Secondly the foundry must check if all requirements can be met, taken in account the shape, wall thickness (the mechanical properties of a lot of materials do depend on the section size) and dimensionally tolerances. The shape must be that no problems can occur with section connections, sharp angles… These problems are completely different per material (strength, ductility…) and depend also on the heat treatment. The foundry must also indicate the tolerances that can be met. This is dependant on the shape and size of the casting and of the type of moulding. But also the pattern concept, size and material, has an influence. The pattern draft must be located that or it must not be removed or it falls within the machining stock.

CASTING

SHAPE

WALL THICKNESS

PATTERN DRAFT

TOLERANCES

CHEMICAL ANALYSIS

HEAT TREATMENT

MECHANICAL PROPERTIES

OTHER PROPERTIES

SERVICE CONDITIONS

STANDARDS FOUNDRY MACHINE SHOP

SHAPE

TYPE OF MACHINING

MACHINABILITY

ASSEMBLY REQUIREMENTS REQUIREMENTS STRENGTH

DUCTILITY

PRODUCT

PART 1 PART 2 PART X…

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3. Features The design can be done quite well by the designer, but this will be at the price of a higher cost and less reliability of delivery. It is necessary to take the benefit of working together with the foundry and machine shop. Only then can brought in a lot of experience and knowledge. The casting will have a high reliability to quality and delivery and performance. The choice of material does not only depend on the mechanical and other properties! Quite a lot of materials do have different strength and ductility in different section sizes. Quite some materials will have difficulties with complex shapes and a large variety of section sizes, due to the cooling after pouring and or heat treatment. The required tolerances will influence cost because they point to the pattern and moulding. The larger the tolerance span, the cheaper the total cost of the casting. But this can lead to a higher machining cost. Therefore it is preferred to compromise for casting tolerance (casting cost) and machining cost. It is important to relate all requirements to an international standard. These standards are clear described, proven to be valid and accepted by every one. They also have a clear required type of testing and certifying. This will avoid discussions later on. Subjective (very smooth surface) and or “not measurable” requirements (free of any defect at all) do ask for a never to win discussion.

4. Conclusion Design has been for too long the single responsibility of the designer. Of coarse he knows the product and the required performance of the product and its components. But the performance does depend on the possibilities of the foundry and the machine shop. Even if every requirement can be met, it is important to know the “span” of the results. Will every casting meet the requirements and what will be the difference between the “best” and the “worst” result? This does not only depend on the ability of the foundry and machine shop but also at the type of casting (shape, material, tolerances…). Only a good and deep discussion, before the design is finalised, can lead to the “best design”. The last factor is that only after that deep discussion, it is possible to get a design with the “lowest cost” and the highest reliability for quality and delivery. The cost is not only the cost of a pattern and a casting. It also involves the cost of repair and or scrapping of castings as well as the cost of rescheduling production and loosing customers because of too late deliveries. Although it seems not the task of the foundry, it must be stressed that it should be part of the “casting delivery”. ================================================================ Menu

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LOGISTICS

LOGISTICS 1. Introduction 2. Flow chart 3. Features 4. Influences 5. Conclusion

1. Introduction This department has to collect all data about the casting and make the production schedule using these data. The purpose it to deliver the orders at the required delivery date, mentioned in the order. If meeting this delivery date is not possible, this must be communicated to the customer and an agreement about a new delivery date must be found. Scheduling in the foundry does work with the hours per department and equipment, the type and amount of material as well as the availability of the mould boxes. There should be a continuous feed back about the progress of the production and contact with the customer about delivery date.

2. Flow chart There are three steps in the activity of the logistic department. The first step is to collect all necessary data about the castings involved. This concerns "standard data" as weight, dimensions, type of material; pattern… and order related data as number of castings and required delivery date. The engineering department provides the standard data and the order related data are written in the order form. The second step is to schedule the production, calculate the delivery date and confirm it to the customer. If the required delivery date cannot be met, it is necessary to contact the customer and get an agreement about a new date. The third step is producing work instructions; week sheets and a capacity plan for the production as well as the paperwork for the subcontracting. The feed back of production must continuously be reworked in the capacity plan and scheduling. These "hot situation" must be communicated to production and customer.

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The last job involved is the shipment of the order and providing all data to the financial department for invoicing the order.

3. Features The scheduling is done with standard data, which must be kept up to date. Each modification of these data will have an influence on the lead-time of the production and delivery time of the order. The delivery time is depending on the standard and order related data, but also on the existing capacity for similar castings. It neither is nor preferred to shift castings to later delivery time as originally planned in order to benefit a new order. Indeed every modification of the planning will affect more than the one or two orders involved. Shipping is part of the job because the scheduling department is continuously aware of the latest state of the production. So they can prepare the shipment and inform the customer about it.

ORDER

CUSTEMOR

SHIPMENT INVOICING

ENG I NEER I NG

SCHEDULED CASTING

ORDER CONFIRMATION

WORK INSTRUCTIONS WORK SHEETS CAPACITY PLAN

DATA / CASTING DELIVERY DATE

SCHEDULING

SUBCON - TRACTING

hoursmetal

mouldboxes

PRODUCTION

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Efficiency can be increased by the scheduling if somewhat extra castings are available (extra to the theoretical capacity) and this in a wide variation of types of castings (large and small, with and without cores…).

4. Influences A delivery date is a “living date”, continuously influenced by the results from the production. These results depend on data, which are not correct, and on the efficiency of the job and the availability of people and equipment. It is important to correct the momentaneous capacity per department to the available and scheduled amount of work. This will avoid the building of stock between two operations and will result in the shortest lead-time. Investments mostly increase the efficiency of the production. This efficiency increase must be introduced into the scheduling calculations. If this is not done, there is a chance that this increase will vanish in easier and less efficient working. The problem of “very short” deliveries (this means shorter as normally, calculated with the available capacity) will have the attention of every one. This automatically results in a less fluent production of other products. This special work also results sometimes in the use of less suitable tooling and mould boxes, which will increase cost of this casting.

5. Conclusion The logistic department is important for the production because it has an important influence on the efficiency. Efficiency can increase if a large variety of castings and a little over numbered are scheduled. It is necessary that the up to date data and continuous feed back of the real production volume be provided. This enables an as correct as possible scheduling. The logistic department plays an important role towards the customer. It can provide the customer with the correct information and establish a trustful relation. The shipment and providing data for the invoicing is the final job per casting. Menu

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ENGINEERING

ENGINEERING 1. Introduction 2. Flow chart 3. Important features 4. Influences 5. Conclusions

1. Introduction This department is the "guard of knowledge" of a foundry. All knowledge is present and kept up to date: 1. Tooling and equipment 2. Manufacturing specifications 3. Material specifications 4. Other foundry specifications 5. Production possibilities. Keeping these files up to date does not mean that "non active" and or "incorrect" procedures and work instructions are forgotten. On the contrary these information must prevent the foundry to re-use them again (sometimes years later). This knowledge includes a theoretical part as well as the extra experience out of the foundry. With the use of this knowledge and the casting features (shape, weight, dimensions and material) the pattern, chemical analysis, inserts and work sheets are set up. It is very important that the engineering keeps aware of new technologies and gets a continuous feedback from the production and inspection and customer remarks in order to modify the production work sheets to get the "best" casting (required quality and lowest cost).

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2. Flow chart There are three major steps in the job that engineering is performing: calculating and verifying the casting data, consulting the available possibilities for the production and setting up the procedures and work sheets for the casting.

The first step is to verify the casting data. The material must be brought in relation with the shape and dimensions of the casting. The properties of a lot of materials (grey iron) do depend on these data and can be mastered by adopting or closer limiting the chemical composition. The dimensions will lead to the best-suited mould boxes. The shape and dimensions must be qualified according to tolerances and importance, taking in account the machining stock. The weight is very important because it has an influence on: 1. number and size of risers and chills 2. necessary amount of liquid metal to pour the casting 3. the use of ladles 4. the pouring temperature. Knowing these basically data, the second step is to consult the files for the best technique to produce a good casting. The use of equipment and tools as well as the production possibility are important to set the pattern concept (split line, number of cores…).

EXTRA FOUNDRY SPECS

DIMENSIONS

ENGINEERINGPRODUCTION DEPARTMENTS

MATERIAL FEATURES

ORDER

WEIGHTSHAPE MATERIAL

moulding

pattern

pouring system

work sheets

chemical analysis

COST OF CASTING

PROPOSAL FOR

INVESTMENTS

TOOLING / EQUIPMENT

MANUFACTURING SPECS

inserts

risers + chills

melting fettling heat treatment

surface treatment

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The manufacturing specifications are identical or similar to previous casting or made new. It must be clear that new castings always have a higher risk for problems and even scrap. Extra specifications and or requirements will be set for chemical composition of the material, for strength of the mould material, for the coating, for the time after pouring and before shake out, for heat treatment… It is preferred to discuss possibilities and proposal with the production and quality control in order to have the maximum input of experience. The third step is the final set up of pattern, chemical composition of the material, and use of inserts, work instructions and inspection hold points. The work sheets do include all instruction for melting, moulding and pouring, fettling, heat treatment, surface treatment and shipping.

3. Important features It looks that people working in the engineering department; have to be more or less encyclopaedia. But this is not true. Working in this department asks for a structurised filing of data and results and a high competence to absorb this knowledge or to find this information easily back. Their theoretical knowledge must be on a high level. The experience will come from working together and a close contact and trustful relation with the foundry workers and the technicians of the suppliers. They need to be open-minded and realise that studying will a never-ending task for them. Another important feature is the availability of all information (including the "why's" behind every instruction) to the foundry workers. This can be as documents or better as pictures, possibly available on line by the intranet of the foundry. Most of the people can read drawings and work instructions to a certain extend but all of them can understand pictures. The engineering department must have filed the materialising of the proper foundry know how (knowledge and experience). These know how may not only be in the head of employees but must be written down or available as pictures. Engineering department is the best suited for calculating cost of a casting. It has know how and knowledge to predict the number of hours and cost of material. If it is provided with the cost per hour, surplus for storing and handling, surplus for non-production costs and financial and other cost, the real cost can be calculated and handed over to the selling department. But because engineering has to propose investments to apply new techniques or to increase the efficiency of old techniques and, in cooperation with the employees involved, find out operation work methods with higher efficiency, it is them which will set the cost of the castings.

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4. Influences It is very important to keep old non-active procedures and work sheets, because they are witnesses of incorrect and or "not best" work instructions and procedures. This will avoid re-using it after a long period of time and will inform new employees for pitfalls, already discovered by others in the past. The cooperation between engineering and quality department and production will avoid that knowledge and experience will not be shared. It must be the purpose to bring as much people as possible on a very high level of knowledge and experience. It must be shared and will increase by sharing! Engineering must learn to work with the available equipment and tools. They will suit for a certain type of castings and be less effective for others. The best production for a new type of castings mostly asks for investments. No foundry - engineering department - can be top of the bill in all type of material and castings! Therefore it is preferred for a foundry to specialise in a restricted number of castings and materials and be the best in it.

5. Conclusion The importance of the engineering department is very high as a "guard of knowledge". This knowledge is partly theoretical and partly due to experience in the foundry. Applying the knowledge and experience and introducing new techniques, it will set the cost level of the foundry With these tool engineering is setting up the work instructions, which have to be followed by the production. If production has remarks and or proposals to do better, the head of the engineering and the production will decide to try and apply this. It is very important to keep all "old work sheets and procedures". These can be taken in account if new proposals come in. Doing this the foundry will avoid to return to working with a not best result. The good and worse, the correct and not correct information must be stored and kept available for consulting by every one involved (especially new employees). To be effective this department must have a close contact with the foundry workers, with suppliers and must know the quality of the castings of other foundries. ================================================================ Menu

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PURCHASING & SUBCONTRACTING

PURCHASING & SUBCONTRACTING

1. Introducing 2. Flow chart 3. Important features 4. Conclusion

1. Introduction These two departments are mostly combined, although that for subcontracting engineering and logistic department is very much involved. The purchase order must reflect the requirements valid for per item of the order. These are from the customer order (castings, inserts, painting…), from the data sheet (raw material, alloys, sand…) and from the work sheets (machining, marking…). Purchasing and subcontracting starts with collecting data and ends when the pur-chased items enter with all required documents and approval of quality inspection. For subcontracting it must be considered that, if this work is not performed according to the requirements and specifications, can cause damage and even lead to scrapping the casting. The value of this damage and or scrapping can exceed far over the value of the subcontracted work. It is important to summary for each supplier his possibilities and performance concerning quality, delivery reliability and cooperation to decrease price.

2. Lay out The purchasing and subcontracting consists of four steps. The first step is to collect all necessary data about quantity, delivery time and quality and delivery requirements. These data are provided by the customer (quantity, material, drawing…) and the engineering or logistic department (work sheet, work instruction, delivery time) and inspection requirements. The second step is the choice of the supplier, which does comply or is considered able, to comply as much as possible with the requirements of the order. The production and delivery of the order items are also involved in this step. The third step is the inspection, according to the order requirements, of the delivered order items. The quality and other documents are also verified. After the approval the goods are taken in the inventory and will be stored.

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The last step is to collect data about quality and delivery time. The data are coming from the inspection department and production as well as from the supplier. These data will lead to a statistically figure about the performance of the supplier.

3. Important features

It is very important that every order is put in a clear and written document, indicating all necessary data and requirements involved. The requirements must be identical to those in the customer order involved.

4. Conclusion It is a fact that besides price, the important items are quality and delivery reliability. To have an objective figure of these, it is necessary to do statistical calculations. Lack of quality or too late delivery will result in costs which can be real costs (repair…) and or disturbing of the production and resulting in a decrease of efficiency. Mostly the castings will be delivered too late. These costs will definitely exceed the price difference between two suppliers. ================================================================ Menu

SUPPLIER DATA

SCHEDULING

SPECIFICATIONS

OTHER MATERIAL

INSERTS…

PAINTING…

CUSTEMOR ORDER

PURCHAS I NG

SUBCONTRACT I NG

LOGISTICS

SUBCONTRACTING

INSERTS…

PAINTING…

PRODUCTION

PRODUCTION

RAW MATERIAL

OTHER MATERIAL

INSPECTION

STORE INVENTORY

DATA

FOUNDRY CASTINGS

SUPPLIER

SUPPLIER

MACHINE SHOP

SUBSUPPLIER

RAW MATERIAL

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PATTERN

PATTERN 1. Introduction 2. Process 3. Important items 3.1 Pattern 3.2 Core box 3.3 Template 3.4 Pouring system / risers / chills 4. Influences 4.1 Pattern condition 4.2 Tolerance 4.3 Quality of the casting 5. Conclusion

1. INTRODUCTION The pattern is the “start” of a casting. Mostly the buyer feels a pattern as an extra cost, to be paid at the start of production, and useless for him. This is a completely incorrect opinion. The pattern has a large influence on the cost, the dimensions and soundness of the material section as well as the surface condition of the casting. It is for this reason that very much attention must be paid on the pattern concerning concept, execution and dimensions. To get “the best” pattern, a cooperation between foundry, machining shop and pattern shop is absolutely necessary. A low cost casting can be the start of an expensive casting, which keeps expensive during the whole lifetime. A “bad pattern” can also be the start of a continuously troubling quality and delivery. The lifetime is quoted as the amount of castings, excluded the scrap ones, to be produced (factor is wear of pattern) or as the time that the pattern must be usable (factor is the degeneration of the pattern material). A more detailed description is given in Chapter 15, in which the FPQ-, SP- and CAQ-production will be compared.

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2. PROCESS The pattern producing process is shown in the following flow chart. It has four steps.

The first step is the production of the pattern drawing, starting from the casting drawing. There are four groups of information used for this step:

1. Casting shape and material to predict the overall and local shrinkage to be applied to the pattern.

2. The type of production concerning mould material (influences the shrinkage and the pattern wear) as well as the pouring temperature (influence on the shrinkage due to the influence on the mould strength).

3. The amount of castings per delivery (number of parts on a pattern plate, mould) and the total amount of casting during the lifetime (number of moulds which indicates the pattern material to use).

4. The final part drawing and machining to set “the zero point” for the lay out and marking as well as the design of the pattern to put pattern draft as much as possible in the planned machining stock.

Shape Pouring temperature

Material Mould material

Order lot final part drawing

Life time machining dr awing

drawing casting

drawing pattern

PATTERN

pattern core box templates pouring sytem/riser/chill

Mould

Casting Dimensional inspect ion

Mould ins pection

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Generally the split line or lines is set, taking in account the pouring system, risers and chills, the assembling of the cores and the machining planes. This first step needs the knowledge and experience with similar castings and material in the foundry. It is nearly impossible to have the best result from the first shot. The second step is the physical production of the pattern, which consists of one or more pattern parts, no or one or more core-boxes as well as the pouring system, the located riser seats and riser-blocks and the pattern for chills to be poured. For complex and or important castings, it is necessary to produce templates, which will be used to assemble cores and cores in the mould cavity. This must result in correct dimensions and a narrow variation in dimensions between the castings. The third step is the “first use” of the pattern to produce a mould, assemble and pour it. The result, the first casting, can be measured and discussed. It is necessary that “all” problems, small and big, must be reported as well as correction “on the spot” done. The engineering department, in agreement with the buyer, can correct the pattern to get a correct casting. The last step is the dimensional modification of the pattern. This is done with the comparison of the real dimensions to the required dimensions, taking in account the tolerances on the final dimensions and the tolerances due to the production. This also can result in another way of assembling or in the use of other templates. It is more severe if the lay out of the pattern must be changed due to an insufficient quality or surface condition. This can lead to another split line for the pattern or new or other cores. If this situation does occur, a new cycle starts again and it does cost a lot of money. It is mostly the confirmation that the foundry did not have or did not use the experience and knowledge about the type of casting and material involved.

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3. Important items This are pattern, core boxes, templates and pouring system with riser and chills. Pattern The pattern can be single part or more parts due to several split lines. The splitting is done because of:

1. size of the mould boxes (especially height) 2. location of pouring system, risers and chills 3. amount and location of draft material (the more splits, the lesser the extra

material due to draft) 4. location and easy assembling of the cores.

The split between pattern parts needs a correct referencing item (mostly conically shaped sand or metal blocs) with a small tolerance span and no possibility to dislocate or rotate one part to the other. The size of the draft is prescribed in standards and guidelines in relation to the dimensions of the casting. But mostly there is insufficient consideration of the complexity of casting shape and mould material. Therefore the foundry has to make the final decision. The gliding paste, put on the pattern, is a help for an easy and non damaging removal of the pattern from the mould cavity. It is also preferred to remove the pattern before the mould material is completely hardened. A damaged pattern surface will also bother an easy removing. The split line can be horizontally or vertically (mostly for serial production and small, not complicated parts). The split will cause a mark on the casting surface and has a risk for some mm of mismatch between the two parts as well as extra length due to the seal between the two mould parts. This will lead to extra fettling and or machining. There are two solutions for this matter:

1. locate the split-line in a plane that has to be machined 2. put an extra “flat rib” so that the extra fettling is easy and restricted to this flat

rib (a plane is very difficult to correct). Concerning dimensions, the expected shrinkage, machining stock and coating layer thickness (especially for small and or thin wall castings) is taken in account. The expected shrinkage is depending of the type of material and the shape of the casting. But the ever varying factors as are the strength of the mould material and the pouring temperature and the thickness of the coating layer do have also a small influence. For this reason literature is indicating always a span of shrinkage values. The real shrinkage will always be smaller than the theoretical one. It is mostly necessary to correct the pattern due to unexpected shrinkage.

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The pattern material is chosen, taking in account the number of parts per delivery and the lifetime of the casting and pattern. Single and unique parts can be made with a pattern in pressed paper, styrene or thin wood. Sometimes an old casting can be used after adapting the dimensions for shrinkage and machining stock. Parts with a low need can be made with a pattern in wood. If the shape is very simple also styrene or a combination with wood can be used. Parts with a low series need can be made with a pattern in wood. Parts with a complicated shape and low need can be made with a pattern in wood and or plastic and eventually mounted on a pattern plate. Parts with a serial need can be made with a pattern in wood, plastic or metal and are always mounted on a pattern plate. Core boxes The core-boxes are used to produce cores, which are mostly completed surrounded by liquid metal after pouring is finished. For this reason they are heavily attacked. They shape the inside part of the casting. Not all castings do need a core. There are also casting that are made without a pattern. The cavity (mostly a concrete box or pit) is filled with cores to make the mould cavity. Sometimes cores are used at the outside of the mould cavity to avoid extra material due to the required pattern draft. A core must be designed for easy filling, which can be done by hand or under air pressure. The core material can be the same as for the mould and or special designed chemical bounded sand (hot box, cold box). The parting or design must be so that placing core stiffeners and gas escape devices can be done in a easy and correct way at the correct location. Core boxes must be composed of parts, which allow easy assembly and disassembly as well with unique and steady referencing items. Core stiffeners, especially for large cores, are preferably made of cast iron in stat of steel. Cast iron does deform less due to temperature increase. The indications on the core surface, due to the split line, must be removed carefully without damaging the core or changing its dimensions. Another important feature is the “core-shoulder”. This is the part of the core which locates the core into another core or into the mould cavity. Because core and mould are made separately and both have tolerances concerning dimensions, it is possible that there is a lot of space. The way of using this space to locate one to another will decide the final dimensions of the casting.

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It is very dangerous to correct core-shoulder by hand, especially if no template is used, for the loss of the final required dimensions. The dimensions of the core must take in account that the shrinkage of the material will decrease the dimensions to an extent, depending on the pressure strength of the core. This shrinkage is mostly much lower as the pattern shrinkage. Also the influence of the coating, up to one mm, will influence the final dimensions. The material, used for the core-boxes, is mostly wood. It can be metal if a lot of cores have to be made during the lifetime and if filling under pressure is used. Templates Templates are necessary to have a correct assembly of cores to cores and to the mould cavity. The template must assure that the tolerance space of both (core and core or mould cavity) is always used in the same way (shifting and rotating). The use of templates can narrow the tolerance on the dimensions of the casting. A template must be referenced to the “zero start point”, which is also used by the machine shop. This point must be situated on a “non machined” plane to assure that dimensional differences can be corrected in the machining stock. The use of a “ok” and not ok” template is mostly not possible because the complexity of the shape and the combination of location of special items. These are not always reachable by templates when they are placed in the mould cavity. It is preferred to assemble the cores aside of the mould, check them by template and fix the assembly so that no dimensional change can occur anymore. The core-assembly can be put in the mould cavity and checked by template before fixing the location. This template only has to check the location of the core-assembly and master shifting and rotating of it. The use of templates will give castings within a very narrow dimensional span. This will benefit the machining and assembling cost. Pouring system, risers and chills It is necessary to use a standard system concerning shape and dimensions. This will prevent surprises during moulding. But is necessary to make reference points for the location of the ingates, risers and chills. These points are physically present on the pattern and or core-boxes. This is indicating in marking or “seats”. If, for exceptional reasons, no standard can be used, the pouring system and riser and chill are part of the pattern.

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4. INFLUENCES

4. Pattern condition The pattern condition has an important influence on the surface condition of the casting. Damage can bother the easy removing of the pattern out of the mould cavity. This is only possible with marks on the mould surface, which will degenerate the surface quality of the casting. A bad pattern condition can require shaking of the pattern in the not yet hardened mould material. This shaking will increase the dimensions of the casting. The referencing items must be in the best condition. It cannot be allowed them to sit loose, to be bended or to have too much wear. The split plane of the pattern is very prone to damaging by removing the pattern of the mould cavity. If pattern(s) come loose from the pattern plate, sand can enter between them. This will change the dimensions and make it more difficult to remove the pattern from the mould without damaging one of them. Tolerances The tolerances are important in two ways: the absolute value and the span due to the reproducibility of the process. These tolerances and span must be compared with the required tolerances of the casting. The absolute size of tolerance, compared to the required dimension, is depending on the size of the pattern and the real shrinkage. These items are mastered by the correction of the pattern. The tolerance span, due to the reproducibility of the process, is mastered by the use of correct templates and a very well control of the strength of the mould material and the pouring temperature. It is important to use the same “zero point” for the design of the pattern and the machining. This zero point must be situated at a non-machined plane. The use of templates will increase the stability of the dimensions and narrow the tolerance. Quality of the casting The quality of the casting depends a lot of the “pattern concept”. The influence on the dimensions is discussed in previous items.

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The quality of the material section (porosity) will partly depend on the possibility of an easy putting of risers and chills. The location of thin sections, section changes… can minimalism the problem of turbulence and high speed of the entering liquid metal and cold runs… The concept of the pattern can also direct the inclusions (sand, slag…) to an area, which is machining stock. If this problem is limited to this stock, it is removed after the machining.

5. CONCLUSION The importance of the pattern in the production of a casting is mostly underestimated and can be the cause of troubling quality and delivery for the rest of its lifetime. The effect of the pattern on the casting is very large: dimensions, machining stock, quality and surface condition. These master these effects there is a need for proper use of knowledge and experience of the foundry. A new type of casting and or material will always have problems in the beginning. It is necessary to design a pattern (pattern, core-boxes, templates and pouring system, risers and chills) in cooperation with designer, foundry, machine shop and pattern shop. Only by doing this, the maximum profit can be taken of all knowledge and experience. A more detailed description is given in Chapter 15, in which the FPQ-, SP- and CAQ-production will be compared. ================================================================ Menu

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MOULDING

MOULDING 1. Introduction 2. Description 3. Influences 4. Coating 5. Special situations 6. Conclusion

1. INTRODUCTION It is important to describe the process of mould fabrication in order to recognise all possible influences on the result of moulding to the condition of the casting. Moulding consist of four important steps: 1. Filling the mould and core boxes 2. Finishing mould and cores (correcting, coating…) 3. Assembling and closing mould and cores 4. Preparing for pouring (clamping and weigthening). The production is guided by methods (work instruction, choice of materials), the result of the used equipment (coating and sand mixers, clamps, mould boxes, pattern and core boxes), and the conformity of the used material with the material specification and the handling and acting of the people. All these have an influence on the result, single and in combination with each other.

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2. DESCRIPTION The process is described in the flow chart below.

Step 1 Filling mould In filling station the area between pattern and mould boxes is filled. The pattern has to be in good condition and must be placed on a flat (floor or pattern plate) in order to have a correct and not deformed mould. The mould boxes are placed some mm above the floor in order to assure a mould part - mould part contact by assembling and closing it. A contact between mould boxes has a risk of non-sealing the mould parts, depending on the condition of the boxes (flatness, straightness, condition of surface of bottom and top of box…). The condition of the pattern will influence the smoothness of the contact sand surface and in this way the surface of the casting.

boxes pattern coreboxnew sand old sand core sand

catalyst catalyst

binder binder

coating coating coating

Filling station mould Filling station cores

coating mixer

assembled mould

clamps weightening

Mould ready for pouring

upper mould lower mould

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The sand is mixed in a machine that first brings new and reclaimed sand together, adding then the catalyst and later the binder material. This mixing must be done in a correct way to ensure the homogeneity of the sand. The sand is falling in the mould boxes and it must be assured that all area is filled with the same density of sand. Ramming or vibrating can do this. The kind and amount of binder that is depending on the kind, grain size and morphology of the sand mixture establish the strength of the sand. The ramming or vibrating can increase the overall strength or decrease it if this action is going on too long time because it can destroy the bounding of the sand grains. The speed of hardening of the sand is depending on the kind and amount of catalyst (compared to the amount of binder) that is depending on the temperature and humidity of the air and the condition of the reclaimed sand (remaining degree of acid). The time for removing the pattern is influenced by the degree of reaction of the chemicals. The strength must be high enough to remove the pattern and handle the mould without damage. Very important for this handling is the presence of stiffening bars in the upper and lower mould boxes as well as in the mould itself. The inside walls of the mould boxes have some features (strap or bar) to avoid moving of the sand along this metal. For the core filling the same remarks are valid.

SAND SAND

SANDSAND

CORRECT TO AVOID

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Step 2 Finishing mould / cores After completion of the hardening of the mould material, the condition of the mould cavity is checked and repaired if necessary. Any repair, if it is possible in a technical way as well as economically, must be made in a way that the repair material cannot loose the base mould material during handling and pouring and that the bound is as tight as possible. In order to assure a smooth surface for the casting, a coating is put on the mould material. This coating has the purpose to: 1. fills up small gaps and holes in the mould material 2. smoothen the surface of the mould cavity 3. resist the erosion and temperature of the entering metal 4. resist the expansion of the sand during pouring and cooling 5. avoid mould gasses to enter the mould cavity and liquid metal. The kind of coating depends on the type of material (chemical nature), the pouring temperature and the wall thickness of the casting. The most frequently used are: 1. carbon based all kind of iron 2. zircon based steel, high-alloyed irons, large wall thickness 3. magnesite based high-alloyed steels (manganese steel, stainless steel). The way of applying determinates the smoothness. Spraying and floating will lead to the best surface, brushing will show strives and lead to the poorest surface. The applied thickness of the coating layer depends on the kind of coating and the wall thickness of the casting. The thickness is easily 1 mm and up. Step 3 Assembling mould and cores The assembling of cores in the mould parts and mould parts with each other is a high-risk job. A lot of incorrect or and avoidable matters can happen and a lot of them cannot be seen during or after assembling the mould. The result can be a defective and or scrap casting. The following summary indicates the important items: 1. Referencing between two or more mould parts or between mould boxes is not unique and or has a large tolerance This can lead to rotated upper and lower casting halves or a shifting between them. The result is a difference in dimensions, machining stock…

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This shifting can also disturb the section and section ratio of the different parts of the pouring system (sprue, runner, ingate, filter chamber…). This can lead to incorrect filling and scrapped castings. 2. Referencing of the core shoulder and mould and or other cores is not unique and or has a large tolerance This can lead to rotate upper and lower core halves or a shifting between them and or unpredictable location of them compared to the mould. The result is a difference in dimensions, machining stock… 3. A core is not assembled so that the shape of the casting is incorrect and or extra machining is necessary or the casting is scrapped 4. The air escapes are not connected to the outside of the mould 5. The sealing of the core - mould connection and or between the mould parts is not correct Metal can run out of the mould cavity and or seal material can touch liquid metal which can introduce gas in the metal or lead to a lack of material (size and shape of the sealing). 6. Sand and or dust and or other items (hammer, clamp, chill…) remain in the mould cavity or fall in during assembling. It can also happen in the pouring system. This will lead to non-conform castings. 7. The air escapes are not open due to blocking with sand, seal material…. Step 4 Preparing mould for pouring This step has to be taken as close as possible to the time of pouring. It is an important step because it must prevent metal from running out of the mould and bring the mould in an optimal condition to pouring (no dust, humidity of chills, clamped properly…). Proper clamps must do clamping. The material must be high strength and ductile. The shape must be that increasing forces are tightening the mould parts and increasing the clamping force. To assure this they must be clean: without rust, metal drips, scale and or grooves (damage). The clamping must be activated equally spread around the mould to prevent deformation. Sometimes clamps are replaced or combined with bolts and or wire rods and nuts. Bear in mind that increasing temperature of these clamps will decrease the clamping force or even loose it.

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The amount of weightening is calculated with the horizontally surface and the pouring height. The blocs must be located in a way to ensure that the effect is equally divided all over the mould area and does not deform the mould cavity. For this reason it is important to have upper mould boxes with stiffening bars. The blocs cannot be located directly in contact with the mould. Doing this can lead to blocking air escapes, risers or at least make it difficult to cover open risers with insulating / exothermic cover. They must be located in a way that they do not bother pouring or decrease the accessibility of the ladle.

3. MOST IMPORTANT INFLUENCES Which are the features that have an important influence on the casting? This are the following five: strength of mould boxes, strength of mould material, reaction speed of the mould material hardening, gas evolution and the surface condition of the mould cavity. 1. Strength of the mould boxes The strength is set by the shape and thickness of the box material. This is mostly stronger if the box elements are cast. These can also resist better the deformation due to temperature increase and handling the mould. It is important to use, as upper and lower box, a box with stiffening bars. These bars do prevent the sand to fall out or move during rotating and handling the mould. It is also advised to provide sand holding bars or other devices at the inner wall surface of the boxes. 2. Strength of the mould material The type of binder must suite the type of sand (silica, chromite, zircon, reclaimed sand…). Each binder has a maximum strength, which can be obtained with the appropriate amount in according to the sand. The sand grain size and the division over the size sieves are very important. The larger the size the less binder is needed. Sand with about 85 % of the sand, belonging to three neighbouring sieves, will get the highest density. Sand with a round grain shape needs less binder than an irregular shape. Ramming and or vibrating the sand do give it a high density and a high strength. This action can only be done in the early phase of the hardening reaction because after a time the bounds between the grains made by the binder, will be damaged and even destroyed and they will not recover anymore. The water content in the binder will limit the strength. But also the catalyst has some water and the reaction also forms some water. This water will soften and weaken the mould material. The humidity in the air has a similar effect but in a lesser degree. During the waiting period, between assembling and pouring, water will interfere with the sand and weaken the sand bounds.

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3. Reaction speed of the sand hardening The main influence is coming from the catalyst. Its nature is important. The amount of catalyst in relation to the amount of binder will increase the reaction speed. On the other hand the amount of water, coming from binder and catalyst, will decrease this. In a lesser degree, the humidity of the air is involved. Decreasing the temperature of the sand, the binder and catalyst and the mould boxes will slow down the speed. The larger the areas in contact with the open air the higher the reaction speed. 4. Gas evolution The most important factor is the amount of binder and catalyst. An increasing amount of binder and catalyst will give an increasing amount of gasses. This sets a maximum amount for them and does influence the strength of the mould material. The LOI (loss of ignition) is a factor indicating the amount of organics present in the sand. These organics will burn above 600 C and cause gas. The lower the LOI the less gas will be involved. The more reclaimed sand the higher the overall LOI. The wall thickness of the casting will influence the temperature of the sand and the amount of sand that is "burned". During this burning gas will be formed. Therefore it can be set that higher pouring temperatures and thicker wall sections will cause a higher amount of gas. The coating needs to resist high temperature and gas penetration. Air and gas escapes in cores are very important. A core is completely surrounded by liquid metal and all gas, formed during burning, must be evacuated through the escapes. 5. Surface condition The surface condition of the mould cavity will be related to the surface condition of the casting. The coating is the most important factor. The grain size of the sand as well the ramming / vibrating will be the other factor. The denser the sand is, the smoother the surface will be. A too high amount of binder and catalyst can also cause a rough surface.

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4. COATING Coating consists of refractory material and a carrying liquid, which can be alcohol, another chemical or water. The liquid is giving some viscosity and fluidity to the coating. The liquid is there to carry the refractory until it is put on to the mould material. It enables the coating to cover and penetrate the mould surface. After being in place, the liquid must be removed. In case of alcohol or another chemical, the liquid will evaporate in time. This evaporation can be speeded up by heating the mould or core or by touching it by a gas flame. The advantage is that it is a "quick process" and there is no risk for explosions. The disadvantage is that it is negative for the environment and people in the surrounding area. It also has a penetrating smell. In case of water, the mould and or core must be heated in a controlled way in order to remove all water. This is necessary because water in contact with liquid metal can give an explosion. The advantage of this solution is a friendliness concerning environment and people. The disadvantage is that it requires a high investment and a similarity in mould sizes. The kind of coating is related to the kind of mould material, the kind of metal and the pouring temperature combined with the section thickness of the casting. A magnesite coating does fit the best for a 12 % manganese steel, a carbon coating for all irons and a zircon coating for unalloyed steel. High temperatures and wall thickness ask for a zircon coating.

5. SPECIAL SITUATIONS There are several situations where other techniques are used: 1. Backing sand For large moulds two type of sand can be used. The layer to cover the pattern, thickness depending on the thickness of the casting section, is made of proper sand as described above. The rest of the mould can be filled with sand, using a much higher amount of reclaimed sand and less binder. Sometimes the area is also filled with sand lumps taken from the shake out. 2. Box less moulding A mould can be made without mould boxes if it is made for a thin wall casting and a material with a low pouring temperature. The advantage is that fewer boxes are required as well as less handling and storing of these boxes.

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The disadvantage is that there is need for a higher amount of sand compared to the weight of the casting and that handling, assembling, clamping and weightening is somewhat more difficult. 3. Vertically split moulds These moulds are mostly made f green sand and used in serial production. The sealing between the moulds is obtained by a horizontally pressure. 4. Other types of sand Several types of sand are used although silica sand is number one followed by green sand (clay, bentonite…). To obtain extra cooling chromite sand is used as well as silica-carbide material. To obtain a smooth surface for thin wall castings zircon sand is used. To avoid a reaction between sand and metal olivine sand can be used for manganese steel.

6. CONCLUSION

The moulding operation, as described here, has an important influence on the quality of the casting. It is important to have the correct "work instruction" as well as that people do understand the influence of different features involved. Without this knowledge they will never be able to make "standby" decisions in suddenly occurring situations. The equipment must work, as it should to get the best possible result. The material should be as purchased in nature, size and quality. And last but not least the importance of the "experience and skill" of people. Whatever on paper, it must be performed by the hand of the master. The result is related to the skill and gift and experience of the performer. This is not a matter of a year but of a lot of years. Each new method and product will have a period with a lot of problems and will be mastered slowly. Menu

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MELTING

MELTING 1. Introduction 2. Steps 2.1 Charge 2.2 Melting 2.3 Ladle situation 2.4 Pouring 3. Influences 3.1 Condition of charge 3.2 Type of melting 3.3 Type of lining 3.4 Metallurgical treatment 4. Critical features 4.1 Chemical analysis 4.2 Metallurgical treatment 4.3 Lining material of furnace and ladle 4.4 Pouring 5. Energy, environmental and working area 6. Summary

1. INTRODUCTION Melting involves four major steps: charge for melting, melting itself (furnace and holding furnace), stay in the ladle and pouring. This is clearly indicated in the next flow chart. The result of melting is very important because it has an influence on the chemical composition, the mechanical and physical properties, the soundness of the material section (porosity, inclusions…) as well as on the surface condition. The most important feature of liquid metal is its "living" behaviour. This means that it is continuously changing in time. This means that each test done, gives the situation on the time of taken the sample or performing the measurement and not at the time of knowing the result.

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Metallurgical treatment

LADLE

Chemical analysis Correction

Metallurgical treatment

Deslagging

Holding

alloysspecial material returns

Melting

iron

Transport

Pouring

steel

Temperature control

Tapping

Metallurgical treatment

Deslagging

FURNACE

Temperature control

2. STEPS 2.1 Charge This involves the type and amount of material that is put into the melting furnace to obtain the required amount of metal with the correct chemical composition. The materials involved can be: 1. "pig iron" and other "basic iron" 2. steel 2a. new as remaining of cut plates, bars, profile bars, sheet, tubes… 2b. used as cut parts (shredder…) It can be "loose" or pressed in "package".

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3. Special material 3a. material made with a special chemical composition (primary melt…) 3b. broken scrap, which homogeneity and composition is very scattering 4. Alloys 4a. ferro alloys 4b. high alloyed material specially made or selected 5. Returns from the foundry production (pouring system, risers, scrapped parts…). The amount of each group is calculated according to their chemical composition (certificates or checked composition) and the melt yield per element. The melt yield is the factor "end composition" divided by the "original composition". It is depending from element to element and from the type of melting furnace, the furnace lining, time of melting (especially those on high temperature or > 1500 °C), the maximum temperature, the size of the charge material and the deslagging procedure. The composition of each group is not necessary stable in the mass. Even large differences can occur (groups as indicated above): Group 1. Very stable composition Group 2a. Stable composition Group 2b. Rather stable composition Group 3a. Very stable composition Group 3b. Very unpredictable composition Group 4a. Very stable composition Group 4b. Stable composition Group 5. Rather unpredictable composition. The condition of the charge material is also involving the melt result: 1. dirty and rusted extra slag and gas 2. wet gas and danger for explosion 3. size can lead to shorter (main frequency electrical furnace) or longer melting time (all other furnaces) 4 Variety of size extra loss of elements (lower melt yield). This charge material is put in the furnace by hand (smaller furnaces), skip loading (cupola, rotating furnace) or by vibrating belts or bins (induction furnaces). 2.2 Melting Melting starts as heat is put into the furnace. The way of melting and the problems that can occur are very different depending on the type of furnace. The main three steps are melting, holding metal at temperature and tapping. The melting is done in two stages: part with solid and part with liquid metal.

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During the time that the charge material is solid, quite some dirt, oil, water and other organic material can be burned and removed from the furnace. This will happen until there is liquid metal. During this time no elements are lost except graphite that can react to CO gas in arc furnaces and oxygen-gas rotating furnaces. When solid material sinks into liquid material, organic material can dissolve in the liquid metal and contaminate it. During this time the material can loose part of the amount per element this will increase with increasing temperature. When all metal is liquid, at a temperature of 100 to 150 C above the melting temperature, a sample is taken for testing the chemical composition. Depending on the result extra material is charged to correct the analysis. The required "furnace analysis" takes in account that extra is added by the metallurgical treatments and some is lost during the further stay on temperature. Mostly two limits are giving where the inner limit is the best and between the inner and the outer limit special attention is required. The holding step starts at the point that the analysis is conforming the wishes. The temperature is increased to the tapping temperature, assuring that the metal is completely homogeneous. Sometimes an extra degassing or de-oxidising is done. The slag is left on the metal until tapping can start because this prevents the metal from heat loss and reaction with the air. The temperature is regularly checked. The last step is tapping, after deslagging of the metal. It is possible to do some metallurgical treatment in the tapping stream or in the ladle during filling. This can be de-oxidising (steel), nodulising (ductile iron) and inoculating (ductile and grey iron). Remark Some treatments can be done, after tapping is finished, in the ladle: nodulising, de-oxidising, de-sulphurising… In this case another ladle is used for pouring. This treatment requires higher tapping temperatures due to the extra heat loss of bringing the metal from one ladle to the other. 2.3 Ladle The ladle transports the metal from the melting furnace to the location of pouring. It is preferred to cover the ladle with a slag binder that also will isolate the metal from loosing heat and reaction with air. During this transport some reaction products will float to the metal surface and will becatched by the slag binder. At the area of pouring all slag is removed by skimming the metal surface. This must be done very carefully.

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Eventually a last metallurgical treatment is done. This can be due to an excess time that occurred between the previous treatment and pouring and that has caused a too high fading of the treatment effect. For iron this will be some extra inoculation. During the stay in the ladle the temperature is carefully checked in order to assure a pouring temperature in a span of +/- 5 C around the prescribed pouring temperature. 2.4 Pouring Pouring will bring the metal from the ladle into the pouring system of the mould and this as clean as possible. There are several types of ladles: 1. lip ladle used for all types of metal 2. T-pot ladle used for iron 3. Bottom ladle used for steel. The difference is the ability to prevent the metal contamination is poured into the mould. A bottom ladle has the best result, after this the T-pot ladle and the lip ladle requires a very skilled operator to deliver clean metal. The problem for a bottom-pouring ladle is to calculate the proper weight of the casting plus pouring system and riser. It is indeed not easy to close the ladle if the mould cavity is full. Pouring can be done directly in the sprue (requires bottom ladle), into a pouring cup (small castings) that prevent air and slag to enter the sprue together with the metal and into a pouring box which acts identically as a bottom pouring ladle. Also the problem of the correct calculation of pouring weight is present. The pouring time is calculated and depends on pouring system and the shape of the mould cavity. It is preferred to check the real pouring time with the calculated one in order to correct the system in a proper way.

Bottem pouring Lip pouring

T-pot pouring

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3. INFLUENCES 3.1 Condition of charge It is clear that charge material must be clean to avoid contamination of the melted material. All organic material can react with elements of the metal as carbon and silicon (oxygen) and manganese (sulphur). It also brings gasses into the metal, as are oxygen, hydrogen and nitrogen. The reaction products will partly dissolve to the metal and partly float to the metal surface or stick to the sidewall lining. Every reaction is related to time and temperature and seldom finishes in a short period of time. Especially not if the stirring effect of the melting furnace is taken in account. Therefore it will be very difficult to remove them effectively. The best way is to avoid them to enter the metal and use clean scrap. Another problem occurs if "other metal" is present. It is a disaster if lead or tin are brought into the metal (present as non ferrous layer or seal rings in scrap). They destroy the metal because the properties are heavily decreased and it is nearly impossible to remove them. 3.2 Type of melting Several types of melting exist: cupola, rotating furnace, main frequency furnace, and induction and arc furnaces. They all have private features and application. Cupola melting is continuously melting, mostly used for grey iron and in a lesser degree for ductile and vermicular iron. It has the advantage to melt at the lowest cost and at a high melt rate. The disadvantages are a low controllability of the chemical composition (especially carbon) and temperature. Even the addition of oxygen does not improve this very much. Another problem is the high pollution of the air (CO and dust) as well is the formation of dioxins. Sometimes "duplex melting' is used. This is melting with a cupola and correcting the analysis in an electrical holding furnace. Rotating furnaces does work with gas or oil and air or oxygen. It is a badge smelter and is used for all types of iron included the alloyed ones, but with the exception of the high chromium alloyed types. It is a rather cheap smelter but the know how to use it is not common use, especially for ductile iron. Main frequency furnaces are partly badge, partly continuously smelters. It requires a long time to get the first liquid metal but it melts at a high rate if the liquid metal heel is present. A special type is the channel furnace, mostly used for non-ferrous metals.

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It also has a high stirring effect that will lead to a pronounced pick up of gas and loss of elements with a high oxygen reaction tendency. This is the reason why it is not common used for steel and high-alloyed irons and steel. The cost is between rotary furnaces and induction furnaces. Induction furnaces are badge smelters that can melt nearly all metals in a very flexible way but has the highest cost. The melt rate is rather high. The stirring effect is depending on the level of frequency used. It is the friendliest smelter concerning environment and people. It is very easy to do extra metallurgical treatments in the furnace by using bottom plugs and or vacuum hoods. Arc furnaces are "all-smelters". They can melt every scrap at a very high rate and at low cost. The problem is that they burn out most of the elements and it is very difficult to bring the metal "on composition" due to the lack of stirring. They cause also very much pollution and are noisy for the people. They are mostly used for steel and sometimes for alloyed steels as manganese steel. They are not suited for irons and stainless steels. 3.3 Type of lining The lining used for melting furnaces and ladles are of acid, basic or neutral nature. The acid one is based on silica, the basic one on magnesite and the neutral one on aluminium eventually combined with silica. Because the lining of the melting furnace is during a long time in contact with the liquid metal at high temperature and a continuous movement, it is sure that interactions will happen. The metal and lining will react and form typical reaction products, mostly using elements out of the metal and the lining. This can lead to high wear of the lining and a high degree of metallurgical slag. So will it be nearly impossible to melt a high manganese steel (12 %) in an acid lined furnace. The manganese present in the returns will also react with an acid lining and this will restrict the relative amount of returns. The same will happen in the ladle but to a minor degree because the temperature is lower and the time of stay is much shorter. The acid lining is the cheapest one and well suited for all kind of irons. The service temperature is around 1600 C. The basic lining is the most expensive one and resist up to 1750 to 1800 C. Especially steel and stainless steel is melted. The lining is very crack sensitive for sudden temperature drops. The neutral lining is suited for nearly all iron and steel, also high alloyed ones. It can be used up to 1700 C.

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3.4 Metallurgical treatment It is impossible to prescribe the correct amount of product that is necessary for these types of treatments. Indeed every badge of metal is melted in a particular way, although the melting procedure is followed to a maximum extend. Because of this, the metal can and will have another content of oxygen, hydrogen, nitrogen, sulphur and other inclusions. This amount and the combination of the amount of the particular elements will determine the metallurgical treatment. It is impossible to do the correct treatment without checking the metal before or using the metal without checking the effect of the treatment afterwards. It is necessary to be aware that the situation continuously change due to the fading effect of the treatment and the continuing reaction of metal with air, lining and slag. For this reason a program should be established to know the influence of temperature, time till pouring and amount of metal on the final result of the treatment. This can be done by a statistical research of several results.

4. CRITICAL FEATURES

4.1 Chemical analysis The chemical analysis is not prescribed in the standards for the irons and mostly required for the alloyed irons and all steels. For the latter materials the span per element is indicated and the real result should be within these limits. The analysis is the final analysis that means in the casting and after all metallurgical treatments are done. The analysis in the furnace is something in between and must be corrected by the extra influence of all addition done trough metallurgical and other treatments. For iron the analysis is set by the foundry, taken in account the requirements of the customer, the section size of the casting and the way of production. It is very dangerous to accept an analysis set up by the customer. For all steels and alloyed irons the analysis is given by the standards. But it is not sufficient, to get the correct mechanical and physical properties, to meet this analysis. It is obvious that some elements do interact and also their combination should be mastered by extra requirements. These requirements are the responsibility of the foundry and come from the experience with this material and type of castings. The analysis also has an influence on the cooling after pouring and the heat treatment of the casting. Elements can have a tendency to form carbides and this fact has an influence on the microstructure. Therefore some rules have to be set for cooling and heat treatment, taken in account the real chemical analysis.

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4.2 Metallurgical treatment It is important to realise that this treatments are reactions and have a fading effect. So the effect will be decreased to an insufficient level. The amount of treatment product must be adapted to the time till pouring and even better till solidifying. Also the temperature has a large influence on the result. For iron (grey, ductile, vermicular) the inoculation is important. This treatment does depend on the number of germs still present in the iron at the end of the melting. The nature and amount of germs does depend on the temperature in the furnace and the time been on this temperature. The correct graphite morphology will only be obtained by a correct inoculation. But if there is too much inoculation the shrinkage during solidifying can increase and lead to porosity. For ductile and vermicular iron the "primary treatment" (nodulising for ductile iron) is necessary to avoid an excess of gas and too high sulphur content. Also these treatments do depend on the condition of the metal at the end of the melting: initial amount of sulphur and gas. The amount of product must be adapted to this result and to the expected time until pouring and solidifying. It is possible to do a desulphurising for iron. This treatment can be set after checking the initial amount of sulphur. Afterwards it is very important to remove the reaction products as quick as possible to avoid sulphur re-entering the metal. Steel is always de-oxidised. This can be done in the furnace, with vacuum and or gas bubbling, or in the ladle. The result must be checked and the treatment must be done as close as possible to the time of pouring. 4.3 Lining of furnace and ladle The lining has a maximum service temperature. Above this temperature, after a short time, the lining will plastify and stop functioning as refractory. This is very dangerous for the furnace. The lining has a chemical nature. If this nature is different from the nature of the liquid material there will be a reaction. But even if the nature is equal it can be that the metal absorbs part of the lining. These facts will set a limit for the use a lifetime of the lining. The density of the lining is important. Is this is very low some of the metal will remain there and can dissolve if the next metal charge is liquid. This can contaminate these metal (for instance iron in a steel charge). For this reason the lining must be as dense as possible and damaged area must be repaired to the maximum. It is also preferred to clean the lining from slag and other sticking material.

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4.4 Pouring Whatever pouring system is used, it is important that the pouring action is done in a continuous and steady way. This will prevent air and other gasses entering the liquid metal and avoid slag to enter the mould cavity. The cleaning of the metal surface in the ladle will avoid difficulties to stop slag entering the pouring device. But for metals with a high tendency to oxidise it can be good to keep an oxide-layer on the surface to prevent excessive oxidising and hold new oxides and slag by sticking to this surface layer. It is important to pour at a height as low as possible compared to the pouring device, to pour at a constant rate and to keep a sufficient high level of metal in the pouring device. If a system with a bottom pouring is used, it is preferred to let calm down the metal and assure that all slag has floated up.

5. ENERGY, ENVIRONMENT AND WORKING AREA Melting is a very critical item at this time for our society because it is using "old material", "raw material" and is causing CO, dioxins and dust output in the air as well as polluting the working area in the melt shop with dust, gas and noise. Melting is using a lot of energy. Energy is not the energy we read on the meter aside the melting equipment. Energy includes also the energy necessary to produce raw material, electricity, gas, and oxygen… This total energy can show another picture as the energy just used by the melting equipment. Melting can be done by using "old material", but the more the more other phenomena will come up. Dirt material must be cleaned and this dirt is waste. If it is burned it disappears in the air. Some other not wanted elements must be removed and oxidising them mostly does this. These oxides do go in the air or must be stored for re-use somewhere else. The dust and oxides can be captured in a filter that also uses quite some energy. The dust must be stored and dumped in special circumstances. The CO and dioxins are very difficult to minimise. Melting will always be working in an area that has a higher temperature, a higher noise level and from time to time some fumes. Isolating and filters will do this but do cost again energy. These items will be discussed over and over and the government will make regulations. But without melting a lot of things and tools will not be available anymore.

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6. SUMMARY Melting is a very important part of the casting process. It does give the material its correct properties in the particular casting. The process is difficult to master because it is a "living process", this means changing in time depending on the used system and temperatures and materials. It requires a lot of knowledge about the particular equipment and working procedures. It requires a lot of experience to evaluate the situation at the time the metal is solidifying. For this reason new material (new for that particular foundry) will always have some difficulties in the beginning until these experience is built up. Melting is controversial concerning energy consumption, environmental and working area pollution. There is no absolute satisfying solution for this matter, Menu

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FETTLING

FETTLING

1. Introduction 2. Process 3. Important features

Unavoidable fettling Avoidable fettling Window on performance

4. Influences Use of correct tooling / equipment Never ending job

5. Conclusion

1. INTRODUCTION Fettling is the most underestimated part of the foundry. Perhaps this is due to the fact that it is hard and dirty work that can be done by nearly every one? Perhaps this is due to the fact that its workers are low schooled? Perhaps this is due to the fact that the fettling department has to correct the non correct performance of the previous departments? The fettling department has an opportunity to be the judge of the foundry by seeing the quality of all done in previous departments: pattern shop, mould- and core-shop, melting shop and pouring. The casting can be seen “at first” and an estimation of the extra work can be done. This extra work is only partly unavoidable; a lot of it can be decreased tremendously. Fettling is the “window on performance evaluation” for a foundry concerning cost and quality. Combined with the evaluation through the quality control (defects after NDT inspection) will complete the total evaluation.

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2. PROCESS There are major steps in the fettling process: shot blasting the unboxed casting, removing pouring system and risers as well as visual inspection and the correcting of the casting surface.

The first step is the shot blasting of the casting. Sand, oxides and other adhering material should be removed by the blasting. The following type of equipment is used:

1. rotating drum with or without blasting, used for small parts 2. automatic blasting with shot, used for small and medium parts 3. hand blasting with shot, used for large and or complicated parts.

The type of shot is depending on the material and the required surface condition of the casting.

surface correcting

fettled casting

risers

visual inspection

finns, burs casting

unboxed casting

shotblasting casting

pouring system unfettled casting

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It is mostly steel shot. For austenitic materials, small grained shot, blasted at low speed will be used to avoid cold hardening of the surface. The material of the shot will be glass, slag or sand. The size of shot and the velocity and amount is depending on the initial condition (as unboxed) of the casting surface: lot of adhering sand, burned sand, inclusions… Also the required surface condition is a factor to take in account. The second step is removing pouring system and risers. This is done after shot blasting because the removed clean material can be re-used in the next melt-charge. This removing is done by cutting discs (for materials as iron as well as stainless steel and manganese steel and high alloyed irons and steels) or by oxi-cutting (for materials as carbon and low alloyed steel) or by shock removing (for brittle materials as grey iron, white iron and high alloyed iron and steel). Oxi-cutting is a fast operation but cannot be used for materials with a low heat conductibility (austenitic steels and iron or brittle grey irons). After the cutting a lot of flatting by grinding wheels is necessary. By shock removing it is necessary to avoid a fracture, which enters the casting material. For this reason a riser-seat is used. There are rules for the dimensions. After removing a lot of flatting by grinding wheels is required. The most important part of the second step is the “visual inspection”. This visual inspection will tell us if:

1. the casting is full and without misruns (cold flaw, laps…) 2. the pouring system has trapped the slag, sand and other inclusions 3. the risers did deliver sufficient liquid metal for feeding by checking:

• rest weight of the casting compared to the initial weight • connecting plane concerning porosity and metal condition.

If the casting is approved to be, at first view, correct, it is released for further fettling. The third and last step is the removing of fins and burs and the correction of the surface to comply with the requirements. Burs are due to miss fitting of pattern parts or of pattern to cores. It will be a continuously returning job for the next castings if nothing is done to correct the fitting. The thickness of the burs do indicate the pouring temperature: the thinner and larger the bur the higher the pouring temperature. The mismatch of pattern- and or core-parts is hard to remove and it is very well possible that the neighbouring area is damaged. Finns are mostly due to the quality of the mould material, type of coating and coating layer thickness and the pouring temperature. This will mostly go together with a high roughness of the surface. Adhering and even burnt sand is very difficult to remove and requires a lot of fettling work. This asks for immediate action in the moulding department and limiting of the pouring temperature.

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Inclusions are mostly easily removable but afterwards the surface must be smoothened to the neighbouring area. The fettling is done with fettling discs put in electrical or air driven equipment. The higher the rotation speed, the faster the fettling is done. The discs are of silica-carbide, zircone or another material. Each of them has a particular lifetime for a particular material. Which material of disc suits for which material is a matter of equipment and experience of the fettlers. Anyhow the material must be chosen that it will not heat the casting material too much (problem for casting material with a low heat conductibility). Too much heat will lead to surface cracks and even to fracture in thin walled castings. So it is also preferred to stop the fettling regularly to allow the fettled area to cool.

3. IMPORTANT FEATURES

Fettling has some important features: there is avoidable and unavoidable fettling work and it can give the best information about the performance of the previous departments as pattern shop, moulding and core shop and pouring.

Unavoidable fettling Removing the mould remains by shot blasting and removing the pouring system and risers is unavoidable. Shot blasting is mostly not a problem for loose sand, but can take a long time if adhering or burnt sand is present. This work can be decreased if attention is paid to the dimensions of the risers and the their location as well as the use of riser seats. Pay attention that this modification do not lead to porosity in the material section! 3.2 Avoidable fettling This is the work that can minimalised to a large extend and even be avoided by the better performance of the previous departments: 1. moulding to avoid surface roughness, adhering sand and sand inclusions 2. pouring to avoid adhering sand 3. engineering to avoid inclusions, turbulent pouring, split lines on planes without machining… 4. pattern shop to avoid mismatch, burs… It is a need to stress the performance of the previous departments to be high quality. This will decrease the cost and lead time of a casting.

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3.3 Window on performance The fettling department is offering the opportunity to evaluate the performance of the foundry. It is the best site to found out the non conformities and has the possibility to find the possible causes because all "witness material" (pouring system, riser, casting…) is still available. The non conformities that can be stated are: 1. concerning pattern * dimensions of pattern in accordance to the cores * draft of the pattern: size and location * referencing between pattern and cores 2. moulding department * quality of the mould department * quality of coating and coating applying * condition of the equipment used * experience and knowledge of the moulders 3. melting department *deslagging of metal * pouring temperature * pouring experience 4. engineering * split line of pattern * location of pouring system * location and shape of connection of risers compared to casting * number of cores and their relation. This possibility to measure the performance of the foundry and to find the possible causes and remedies to solve the problem, is seldom used as it could be. It is a waste of experience and knowledge increase!

4. INFLUENCE 4.1 Use of correct tooling / equipment To have the maximum efficiency, it is necessary to use the best tooling and equipment. Incorrect tooling can also damage the casting. Shot can be too light and have a too low speed. This results in long blasting time and mostly in an insufficient removing of the adhering sand and inclusions. This can only be overcome by a extra amount of fettling work. Shot can have a too high speed and this will roughen the casting surface and possibly deform thin castings. Shot can damage the casting permanently be work hardening the surface and or introducing shot material in the surface. This will be the case if austenitic stainless steel is blasted with sharp and heavy steel shot.

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Rotary drums, without or with shot, can deform and break the castings, especially thin walled complex castings. Using oxi-cutting for materials with a low heat conductibility and or brittle nature, will cause cracks and probably fracturing (grey iron, austenitic iron and steel). Also heavy duty cutting or fettling with a lot of pressure on the discs, can cause the same phenomena as oxi-cutting (high manganese steel). The use of a chisel in air operating equipment or small sharp discs during cutting or fettling can mark the surrounding area. These marks can ask for more fettling… The nature of the cutting and fettling discs will influence the time of fettling and cutting. It is preferred to do tests and cooperate with the supplier of them. 4.2 Never finishing job It is a job, which is never finished because: 1. there will always be an area which does not comply completely 2. fettled area aside of a non fettled one will give a subjectively unsatisfying feeling 3. mostly no real comparison material is available 4. area will be difficult to reach and work at 5. the evaluation is highly subjective. Therefore it is necessary to have reference standards available and a close surveilling of the boss of the department and quality controller involved.

5. CONCLUSION The fettling operation is a costly and time consuming job which is mostly underestimated. The operators are not paid as moulders and are considered as those which have to correct the insufficient performance of other departments. The job is very difficult to describe and to make procedures for it. This is so because the situation will be different from casting to casting and the evaluation is highly subjective. To overcome this it is preferred to have master samples of material cast in the own foundry. During this job a foundry has a open window on the performance of the foundry because all non conformities and defects can be stated (excluded those at the inside of material sections). It is very important that all material involved is still there and the causes can be found more easily. ============================================================== Menu

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HEAT TREATMENT

HEAT TREATMENT 1. Introduction 2. Process 3. Types of heat treatment 3.1 Treatment with change of microstructure 3.2 Treatment without change of microstructure 3.3 Treatment without change of microstructure and mechanical properties 4. Influences 4.1 Temperature 4.2 Time on temperature (dwelling) 4.3 Heating and cooling rate 4.4 Atmosphere 4.5 Loading 5. Conclusion

1. INTRODUCTION Heat treatment is the "process" that brings the castings on "another temperature" as room temperature with the purpose of changing the mechanical properties of the material, decreasing the stress situation in the casting and or preheating the casting for welding or cutting risers or deforming the casting… The mechanical properties can be changed, strength as well as ductility as well as hardness. It is sometimes even possible to change physical properties; The microstructure is the base of all this possibilities. There are treatments that do not change the mechanical properties. They will, to some degree, stress relieve the casting. For welding the casting or cutting risers or deform it, the casting can locally or as a whole be heated to a low temperature. The temperatures at which heat treatment must be performed will change from casting to casting because the transformation of microstructure is depending on the chemical analysis of the casting involved. Castings, from different pouring badges, will have a different chemical analysis.

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2. PROCESS The process is described in the following flow chart:

The first step is the loading of the furnace. This must be done in a way that: 1. the free flow of air around the castings is guaranteed 2. no burner flame can touch a casting 3. all castings will have nearly the same temperature and that this temperature is about the temperature indicated by the thermocouples. It is not allowed to enter castings in a furnace with a temperature above 100 °C. This will cause a thermo shock, which can lead to cracks and deformation, especially for complex castings and or casting of a material with a low heat conductibility (austenitic microstructure).

Casting Casting Casting Casting

HEATTREATED CASTING

Loading

SUBZERO

Cooling

Dwelling

FURNACE

Air Water Other

ATMOS- PHERE CON- TROL

Heating

Dwelling

Heating Cooling furnace

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The second step is bringing the castings on the required temperature and keeps it that long that the complete section is on temperature and the required transformations and processes (carbide dissolving) are performed. This temperature is mostly higher as room temperature but there is now a treatment with a lower temperature (subzero treatment). The heating rate depends on: 1. shape of casting 2. material of the casting 3. the load of furnace compared to the capacity. The time on temperature, dwelling time, depends on the section size of the casting and the type of material and the time needed for the required transformation. Transforming from the ferrite to the austenite structure will be quicker than the time needed for dissolving carbides into the matrix. The higher the temperature the lower the time needed for the transformation but the larger the grain size will be. The furnace atmosphere has an importance for the oxidation damage of the casting surface and even for de de-carbonising of it. A casting with an oxidised surface will have problems in a corrosive service and castings with a de-carbonised surface cannot reach the theoretical strength and hardness, as expected for the original chemical composition, anymore. The higher the treatment temperature, the more pronounced oxidation and de-carbonising could be.

3. HEAT TREATMENT There are three major categories:

1. with a microstructure transformation 2. without a microstructure transformation 3. without any change of structure and material properties

Treatment with a microstructure transformation These are normalising, soft annealing, hardening, tempering and subzero treatment. Normalising is the treatment that transforms the material to the austenitic structure at temperatures above the Ac-temperature. After the transformation is finished, the castings are cooled in calm air.

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The result is that the grain size of the material is decreased and homogenised. The stress level will also be decreased. The material has all over the section the same properties. Soft annealing will bring the material to the austenitic microstructure followed by a cooling until just below the austenitic zone (Ac-temperature) and staying at this temperature to allow the formation of soft ferrite. When all austenite is transformed the material will cool to room temperature in the furnace (for complex shaped castings) or in calm air. After soft annealing the material has a lower strength and hardness and most of the carbides will be dissolved and do not form again during cooling. Hardening is the treatment that transforms the material to the austenitic structure at temperatures above the Ac-temperature. After the transformation is finished, the casting are cooled very fast (quenching) which allows the transformation to the martensitic structure. The minimum rate of cooling depends on the chemical composition of the material as shown in the CCT-diagram. The final microstructure consists of martensite and possibly some bainite and some austenite. Tempering is the treatment that must follow each hardening. This tempering will, if austenite is present, transform it to pearlite, bainite and sometimes extra “secondary carbides” will be formed. The strength and hardness will decrease but the ductility will increase. The subzero treatment is used to transform the austenite structure to martensite. This happens in the temperature zone below the Ms-temperature (martensite-start) and even below the Mf-temperature (martensite-finish) where no austenite can exist anymore. After the transformation the cooling can heat again to room temperature. It is preferred to temper the material after this treatment. The material will have the maximum strength and hardness but a very low ductility.

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3.2 Treatment without a microstructure transformation These treatments are tempering, solution treatment and globulising carbides. Tempering is the treatment that will decrease the transformation stresses (martensitic formation). The microstructure itself is not changed. The strength and hardness do decrease a little and the ductility does increase a lot, depending on the temperature. Solution treating is done with materials that have an austenitic structure and some carbide and possibly other precipitates. The material is brought to a temperature, mostly in the range of 1.000 °C, at which carbides and precipitates do dissolve completely. The higher the temperature the quicker the dissolving will be finished. The cooling must be very fast, especially in the zone where carbides and precipitates are formed, in order to avoid the formation of new ones. An increasing stay at the treatment temperature will lead to an increasing size of grain, which will result in a small decrease of ductility. Globulising carbides are done with non-austenitic materials. The material is heated to a temperature just below the Ac-temperature (start of austenite transformation) and during the stay at this temperature the carbides will globulise. No microstructure is changed and the ductility will increase. For ferritic high alloyed irons and steels a stress relieve and globulising will be done at a very high temperature (700 to 800 °C). The treatment decreases the stresses and increases a little the ductility. The longer the stay on this temperature the larger the grain size will be and this will decrease the ductility. No microstructure and strength is changed. 3.3 Treatment without any change in structure and mechanical properties Stress relieving is a treatment, which decrease the stresses in the casting. These stresses are due to cooling, welding, cutting risers… and not due to transformation of microstructure. The most influencing factor is the temperature and in a smaller degree the time on this temperature. No mechanical properties of the material are changed. Preheating can be done in order to be able to do some welding or deformation. Material on a higher temperature has a lower strength and a higher ductility. With a higher ductility they can resist crack building. No mechanical properties or structure is changed.

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4. INFLUENCES

4.1 Temperature The temperature is the most important item for a heat treatment. Each treatment has a temperature span and these temperatures depend on the chemical composition of the material. There are several important temperatures for each material (see CCT-diagram): 1. Ac-temperature This is the temperature that forms the borderline between the area of material with an austenite structure and the area with an alpha crystal structure (ferrite, pearlite, bainite, martensite). This temperature is not valid for materials with an austenitic structure. 2. Ms-temperature At his temperature, still cooling, the transformation from austenite to martensite starts. The amount of transformed austenite is depending on the temperature and not on the time. 3. Mf-temperature Below this temperature no austenite can exist anymore because it is completely transformed to martensite or another alpha crystal phase. The higher the temperature above the Ac-temperature, the faster the transformation will occur. The grain size of a structure will increase if there is no transformation. For iron, a high temperature can kill the germs necessary to obtain a good free graphite morphology. But there is a “best” temperature, resulting in the best combination of strength and ductility. At a sufficient high temperature carbides and precipitates will dissolve into the structure and disappear in this way. The most important point is that the thermocouples, which do master the furnace activity, measure the temperature that is identical to the temperature of the casting. This is very difficult and the only way to obtain this to a high degree, is fixing the thermocouple wires to the casting. If the temperature is not correct, it is possible that:

1. it is out the required temperature span 2. it is lower or higher and consequently points to a different dwelling time.

Both possibilities will lead to an incorrect treatment.

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4.2 Time on temperature (dwelling) The time on temperature is less important than the temperature itself. Because the transformation is a process, it needs time to finish. Therefore the time on temperature must equal the sum of the time necessary to equalise the tempera-ture throughout the casting section and the time the transformation requires. Dwelling on a high temperature can cause grain size increase and this fact will lead to a small decrease of the ductility. De-carburising and oxidation will also increase a bit with longer times on high temperature. 4.3 Heating and cooling rate The heating and even more the cooling rate are important. The heating rate has to be so that the section can equalise the temperature of the core and surface in a short time. This time depends on the heat conductibility of the material and the location of the parts in the furnace, especially the distance to the burners. Any touch of the burner flame will lead to extreme temperature differences and causes deformations and cracks. Also between thick and thin sections in the same casting, temperature differences will cause thermal stresses. The stresses can lead to cracks. During the dwelling on high temperature, these stresses are decreased a lot. The cooling rate is different from material to material and can be found in the typical CCT-diagram of the material. This diagram is unique for a material with a particular chemical composition. Depending on the section size another type of cooling is needed. It is very important to limit the rate to that one which will not cause deformation and or cracks in the material. The more complex the shape of the casting, the lower the cooling rate must be because a non uniform cooling will definitely lead to deformation. It is nearly impossible to correct deformation due to incorrect heat treatment! 4.4 Atmosphere The atmosphere in the furnace is very important due to its influence on the surface of the casting: oxidation, de-carburising... Nearly all materials will de-carbonise during heat treatment at a temperature above 700 °C if the atmosphere is oxidising. This loss of carbon in the surface area will lead to a loss in strength and hardness after quenching. Stainless steel will loose carbon but also a lot of chromium. This chromium is necessary for the corrosion protective film in service conditions. Each loss of chromium will lead to a decrease in corrosion resistance. This phenomena is also valid for heat resisting materials.

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4.5 Loading The loading of the furnace must be in that way that the furnace atmosphere can circulate around the castings in a freely and equal way. All castings must be heated up as equal as possible. Mostly, the bottom part, especially if it touches the floor of the furnace, does give a problem. Any touch of the burner flame will lead to extreme temperature differences and causes deformations and cracks. But during cooling this item is even more important. Small changes in cooling rate can cause the formation of other microstructure. It is nearly impossible to give a full loaded furnace (in weight and number of parts) a correct cooling to all castings involved. If the cooling is not equal per casting, the casting can deform.

5. CONCLUSION The heat treatment is an important production step for a casting in order to obtain the required mechanical and physical properties and be free of stresses. It is a dangerous operation because quite some things can go wrong. The surface can be de-carbonised or oxidised too much. The surface can have small cracks, which eventually can go through the section and lead to fracture. Complex shaped castings can deform in a way that the dimensions do not match anymore. These deformation cannot be totally corrected. If properly done, a heat treatment which is set up according to the real chemical composition of the material and which does take in account the complexity of the shape of the casting, the results can be a very good material. Material with nearly all wanted properties can be produced. Menu

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DRAWING MARKING INSTRUCTIONS

MACHINE SHOP FOUNDRY

MARKING

MACHINING

INSPECTION

CASTING

MACHINING & MARKING

MACHINING & MARKING

1. Introduction 2. Flow chart 3. Feature 4. Conclusion

1. Introduction This job is mostly not included in the foundry activity. Marking must be done, if not by the foundry, by a specialised sub-supplier. This is necessary for the first, and even more if this does not comply, casting to assure the dimensional quality of the pattern. Machining is done by specialised companies and is a completely different job as producing castings. The circumstances in a foundry are not suitable for a good machining. Marking and machining are, for the customer, a integral part in the production of the component they need.

2. Flow chart This job is a single step job.

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The casting and drawing and marking instructions are used to set “the zero point”. This point is as well as for the foundry (pattern and mould assembly) as for the machine shop the starting point for further production. The marking is done before the machining, because it is the start of machining. The marking is the confirmation for the foundry that the casting production complies with the dimensional requirements. The inspection, mostly dimensional and surface roughness, must be done with certified equipment and competent (certified) operators. The results must be put in a report, which will accompany the casting in further production.

3. Features The most important feature is the “zero point”. This zero point is the starting point for the marking and machining. It must assure that the casting can be machined without any dimensional problem. The zero point is the result of the pattern concept and the mould assembly (putting together mould parts and cores). Therefore a continuous feedback after marking is necessary to confirm or to be able to modify the pattern and mould assembling. The zero point should always be situated on a non-machined (as cast) plane! The cost of machining can be higher as the cost of a casting. If machining is done incorrectly, probably due to incorrect marking, the casting is mostly lost too. Therefore the sub-supplier for marking and machining must be reliable and familiar with castings.

4. Conclusion Marking and machining are no foundry jobs, but belong to the component production for the customer. If these jobs are performed incorrectly, the foundry is also involved. It can lead to repair and or scrapping of the casting. The “zero point” is the most important item in the casting production, especially for complex castings. It is an item, which involves the foundry and the sub-supplier of marking and machining. All inspections must be done in a correct way, which is with certified tools and equipment and by competent operators. The report will accompany the casting in further production.

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SURFACE TREATMENT

SURFACE TREATMENT 1. Introduction 2. Process 3. Important features 4. Influences 5. Conclusion

1. INTRODUCTION

The surface of a casting has its proper requirements. It can be that nothing is specified and than there is no treatment at all unless the foundry does want this surface to comply with their standards. A specialised treatment is mostly done by subcontractors, which are well equipped and specialised in the treatment involved. It is very important that the surface condition after the treatment is clearly described and or visualised. The best situation is that there are international accepted standards. The purchase order from the foundry to the subcontractor must indicate and specify all requirements, asked for by his proper customer.

2. PROCESS

In this process there are possible routes: 1. no requirements and no treatment done 2. shot blasting the casting after fettling. If there is no requirement and the casting does look good, the casting can go to the final inspection as it is. This can be the case if the customer does him self still some treatment. Anyhow it pays if the foundry looks to send only castings, which look good. 3. subcontract specialised treatments.

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After fettling the foundry can do another shot blasting to: 1. equalise the surface between fettled and as cast area 2. comply the surface with the requirements. This shot blasting mostly is done after the NDT-inspection (non destructive testing as are magnetic, penetrant, ultrasonic and X-ray) because this test can leave products, used for the test, on the surface. This shot blasting can be done with the same shot as the shot blasting after removing the casting from the mould, sometimes a finer and more round shaped shot is used. This assures a better surface roughness. If a special treatment is required, this is mostly performed outside the foundry. These treatments can be:

1. painting 2. surface hardening 3. metalising 4. another layer. Painting can be done to prevent rusting of the casting. If this is the case, no special requirements will be asked for and the foundry can do this. If painting is required with requirements on layer thickness and adhering force, the shot blasting and cleaning cannot be done in a foundry shot blasting equipment. The surface condition and the cleanliness will be higher as the foundry can get.

Final inspection

metalising Other layer

Shotblasting / cleaning

Shotblasting / cleaning

Shotblasting / cleaning

Shotblasting / cleaning

NDT inspection

Shotblasting

Casting

Shotblasting

Painting surface hardening

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Surface hardening is done in special cases. The casting must be free of scale and oxides and inclusions. Surface hardening does require special equipment and skills. If the casting must be metalised, a cleaning in a bath after a shot blasting is mostly preferred. It can also be that the treatment does require a specially adapted chemical composition of the casting material. Chomating an iron will ask for a low silicon level. After the treatment the final inspection can be done.

3. IMPORTANT FEATURES

It is well known that a surface treatment does have requirements. These requirements are mostly not international standards but "company made". Therefore it is important to discuss these requirements with the sub supplier and to agree about the features, which are important, and on which some wishes are valid. Never accept requirements without knowing from a specialist that these do meet the possibilities of the material.

4. INFLUENCES The moulding process will, too a very high extend, fix the surface condition. All work to be done to correct the surface will not be beneficial for the surface treatment because there will be two types of surfaces: fettled and as cast. It is very dangerous to weld or repair with "liquid cold metal" a surface. As a matter of fact the surface treatment will react on this area very different. Defects, just below the surface, are very dangerous for all treatments that are done on a higher temperature. Indeed these defects can blow up the surface and destroy the treatment.

5. CONCLUSION The surface treatment is every operation that will change the surface. This treatment can be painting to protect the casting for rusting. The requirements for this treatment are not that complex and therefore, in most cases the foundry does it. Specialised companies that are experienced in the treatment involved must do the other treatments. It is very important to make sure that the sub supplier will work according the correct requirements and the foundry is advised to inspect the treatment results. This asks for a certificate or can be done by an independent surveyor. Menu

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QUALITY DEPARTMENT

QUALITY DEPARTMENT

1. Introduction 2. Flow chart 3. Features 4. Influences 5. Conclusion

1. Introduction

The quality department has the purpose to inspect castings in such a way that all delivered castings do meet the customer requirements and the foundry specifications. To fulfil this job, there is more than inspection. There is also a quality system, the certifying of instruments, tools and operators, as well as the knowledge of the specifications and requirements, which are mentioned in the order. If nothing is mentioned in the order the foundry specifications and requirements will be valid.

2. Flow chart The quality inspection is an operation, which can be done in several ways, depending on the requirements.

The inspection can be visual, dimensional, material properties, surface condition and NDT (non destructive testing). The visual inspection concerns the first inspection, very cheap and easy to perform. It does involve mostly the shape and surface. It is an subjective test. It can lead to scrapping the casting or ask for extra objective inspection. The dimensional inspection is done according to the casting drawing. The results are compared with the nominal dimension and the tolerance span. The important point is

CASTING

CERTIFICATE

SURFACE CONDITION

NDT - TEST

QUALITY SYSTEM

CERTIFYING

REQUIREMENTS

QUALITY INSPECTION DIMENSIONAL

VISUAL

MATERIAL

FOUNDRYACCEPTED CASTING

REJECTED CASTING

PROCEDURES

TOOLING

OPERATORS

ORDER

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to use the same starting point (zero point) as is indicated on the casting drawing and used by the machine shop. The material properties include rupture stress, yield stress and deformation on the different kind of tension: tensile, pressure, bending… The test is mostly done for the tensile conditions and is done on special cast material bars. The shock and impact tests are done to validate the service temperature range. Hardness is an easy test. The result is related to other tests (tensile strength) and is an indication for the machinability. The surface condition concerns the roughness. This test is partly objective and partly subjective. The difficulty is to decide the size of the area, which is not conform. The NDT inspections concerns: 1. penetrant (PT) surface condition 2. magnetic (MT) surface condition and layer just below 3. ultrasonic (UT) surface and section material 4. X-ray (XT) surface and section material. This inspection does not damage the casting and therefore it is named “non destructive”. To perform the inspection there is a need for a system, an authorisation and information. The system is called the “quality system” and does set the rules for the functioning of the quality inspection. This involves as well the inspection of the casting as the tooling as the production. The authorisation is got after certifying the procedures, tools and operators. They have to perform tests according to international standards and perform the job involved very regularly. The information is found in the order, indicating the standards and quality level to apply. The quality level can be different according to the type of test. If no quality is mentioned in the order, the rules of the foundry’s standard quality are to apply. After performing the inspection, the casting can be rejected. Each rejected casting can be scrapped or repaired. After the repair a new inspection must be performed. If the casting is accepted, it gets its certificate of conformity. If the customer has asked for it, it will keep together with the casting. To do this each casting must be marked with a unique serial number.

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3. Important features

The quality inspection must function in and according to a quality system. This system must cover:

1. rules to be followed to inspect the product and production as well as administrating, engineering…

2. inventory of tools with a valid certificate 3. inventory of operators with a valid certificate 4. scheduled internal and external auditing.

In this system the “foundry quality standard” must be mentioned and described. Any inspection is valid if there is a written procedure of inspection, the requirements that were used as standard and a written report. A certified operator must do this. If one of these conditions is missed, the results of the inspection are not usable.

4. Influences The inspection and quality system can refer to different standards. Mostly the standards from different countries do not comply completely, but are very similar. Therefore the foundry system uses a standard, which does meet the requirements of several standards. It is preferred to inform the customer about these differences and probably ask permission to use it. A qualification by a third party (Bureau Veritas, Lloyds Register of Shipping…) is a timely and costly operation. If once certified, it pays to keep certified by a regularly (mostly yearly) small test and question for prolongation. The value of an inspection is “zero” if the equipment and tools and probably the operator are not certified. Also a certificate has a validity that is timely restricted.

5. Conclusion The most important feature is that quality must be inspected by an according to certified operators and rules and with certified equipment and tools. The standard can be a agreement between buyer and foundry. If the certification is not there, the value of the report is zero. It is important that quality inspection does more than just reporting. By describing circumstances and appearance, it can help production to correct the non conformity for the future. Quality can only refer to a casting if this casting is marked with a unique serial number, which is also appearing in each report. ============================================================================= Menu

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REPAIR

REPAIR 1. Introduction 2. Flow chart 3. Important Features 4. Influences 5. Conclusion

1. Introduction The need for repair is the consequence of the fact that the casting does not meet some requirements concerning material section, shape and or surface condition. It is preferred to do repairs after informing or receiving permission to do it from the customer. The decision to repair has several aspects: technical, commercial and economical. The repair must technically be possible and accepted. The repaired casting must meet the order requirements and if not, the permission of the customer and or surveillance office must be given. This concerns the shape (dimensions), material strength (strength and ductility), quality of the material section (porosity, cracks…) and surface condition (corrosion, erosion…). The repair must be commercially accepted. Whatever technically possible, if the customer and or the market does have negative feelings about the type of repair or the repair as such, the foundry should consider to do it. It can spoil a good name. If the delivery time is critical, it can be a factor to do a repair because pouring a replacement casting will take a lot more time and delivery retarding. The repair must be economically acceptable. If the total repair cost (preparing the repair, repairing itself and inspection and reporting after repairing) has a high level compared to the casting cost, it should be considered to forget about repairing. Each foundry should set a standard cost (relative to the casting cost) as a maximum for repairing. If the cost is higher it pays to pour a replacement casting.

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2. Flow chart There are three steps for a repair: preparing the repair, performing the repair and the inspection and reporting about the repair.

The preparing of the repair is the first step. The question if the repair is technically possible must be answered first. The type of repair, which does suit the best, is chosen. The customer must be asking if this is allowed. To make this decision possible, the foundry must provide him with all data about the non-conformity and the type of repair. Only after a written permission the repair can proceed. The second step is the performing of the repair. The repair can be one of the following possibilities: 1. removing material and smoothen the area 2. removing material and put a plug in this area 3. removing material and weld the area involved. Smoothen the area is the easiest and lowest cost repair. It can be done if an excess of material and or strength is available or if no other material (weld material) is allowed (possibly for corrosion reasons). This is mostly done for high-alloyed irons and if the defect is minor. Removing material and put a plug is possible for non-conformities with a restricted dimension. Mostly the defect is drilled and a plug of identical or similar material plugs the hole. This is mostly done for irons.

INSPECTION WELD

INSPECTION

ACCEPTED CASTING REPORT REPAIR

WELD PROCEDURE

HEAT TREATMENT WELDINGCERTIFICATE

NON CONFORM CASTING

NDT - REPORT CUSTEMOR AGREEMENT

REPA I R

SMOOTHEN AND FETTLING PUT PLUGS

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Welding is the most performed repair, especially for steel. A certified welder and an accepted and approved welding procedure must do welding. The inspection during welding is part of the repair. It is possible that welding does require a preheating of the area to weld or even of the complete casting. For some castings a soft annealing is required and a preheating. There can also be an interpass temperature, which is the maximum temperature of the weld and casting during the welding process. Mostly the casting will be stress relieved after welding. Sometimes it is necessary to redo the required heat treatment, especially for quenched and tempered materials. The last step is the inspection of the casting and especially the repair itself and the surrounding area. It he non-conformity is removed and the quality according to the requirements, the casting is accepted. The report of the repair must be made and is an integral part of the delivery.

3. Important features The first important feature is the question of a repair to be done or not. This decision must be based on several aspects: technical, economical, commercial… The fact is that a repaired casting will never be “clean” anymore and always be accompanied by a repair report. Another feature is that the requirements for the repaired casting must be clear and agreed by the buyer and foundry. These requirements can be different from those, which are valid for the casting. The third feature is the fact that a written report is an essential part of the repair. This report must describe the defect or non-conformity, the preparation of the repair, the repair itself, the treatment after repair and the results of the inspection. “certified operators” must do all inspection. This repair report is part of the repair cost! The fourth feature is that, repair not been scheduled, will increase the lead time of the casting involved and mostly the delivery time will be longer, leading to late delivery. But mostly, scrapping the casting and pouring another, will even lead to later delivery.

4. Influences The possibility to repair will depend on the service conditions (temperature, corrosion, erosion) and requirements (strength, ductility, quality of material section and surface…) of the casting as well as of the material of the casting (machinability, weldability…). The non-conformity must be quantified according to these aspects. If stress is the requirement and the amount of “good section” is sufficient to withstand these, perhaps no repair should be made.

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But if the defect is a crack, there is always a risk of growing and it is preferred to remove the crack and smoothen the area. If corrosion and or erosion are involved, the removal of the defect area is necessary. If stress is a problem, the defect area must be cleaned and repaired. The easiest repair is repairing a restricted and small area. If the metal can be drilled, drilling and putting a plug in identical or similar material remove the defect. The plug can be fixed by screw thread or pressing force (putting in place on a much lower temperature). Welding must do the repair for a large non-conform area. Depending on the casting material, this can be impossible (not weldable), restricted possible (iron with nickel weld material) or without problems (steel with identical weld material). Anyhow the weld material must meet the service and other requirements and if temperature changes are involved, it must have a very similar thermal expansion coefficient. Large and not deep defects can be metal sprayed (preferable hot spraying).

5. Conclusion Repair is never planned. It is the result of the non-conform casting due to a not correct production. It will always increase the lead-time of the casting. The best repair is no repair! Repair is always increasing cost and it is the first rule to consider scrapping the casting and replacing it by a new one. This scrapping is possible if the foundry is confident that the cause of the non-conformity and the solution for it is known and the next production will be correct. Technical reason can forbid repair. This can be the repairability of the material and the fact that the repair will never meet the requirements. Also commercial reasons can lead to not repairing. A repaired casting is stigmatised for the rest of its life and this is not a positive marketing factor for the foundry. Each repair needs a written permission of the buyer and or designer and must have a written report. It can be smoothening the area, plugging and welding or spraying. A repair will always bring some more responsibility, even for the final product, to the foundry. This responsibility is very difficult to quantify because the foundry is not fully aware of the service conditions and design stresses. The consequences can exceed far the value of the casting. Therefore it must be handled very carefully. Menu

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Sales

SALES & MARKETING

1. Introduction 2. Flow chart 3. Features 4. Conclusion

1. Introduction Sales & marketing is a department of the foundry, which gives it a window to the market. A customer communicates with the foundry with the help of this department. It is to assure that all information about the customer and the market and the deliveries do penetrate to the foundry and its quality department. On the other hand the technical and quality possibilities of the foundry must be made available to the customer and the market.

2. Flow chart

This department has three major tasks. The first task concerns the handling of requests, offers and orders. The second task is to master the information flow from and to the customer. The third task concerns the gathering and providing updated market-information to the management and quality control department of the foundry. Sales organises the flow of each “request for quotation”. The production department as well as the quality control department have to evaluate and quantify the cost. Sales will communicate the information and “price” to the customer. The price is set up, starting from the cost price and adding a margin, which depends on the market situation, the relation with the customer and the intention to do business with this particular customer and market (for instance first delivery). The offer is discussed with the customer in order to recognise its value and the appreciation of the customer. It is important to know the reason for not approving the offer and ordering elsewhere. If the offer is validated sales must inform about the requirements and special wishes in order to communicate these correctly to the foundry and especially the quality control department.

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The order communication must be send as quick as possible. The customer must be informed continuously about the production and the expected delivery time. But contact about the delivery is necessary because at that time, the purchasing department of the customer will know the judgement of its production and quality department. It can be that extra wishes are expressed. This information must be communicated to every department in the foundry. Customer complaints must be handled very carefully. The customer must feel that the foundry does react and does its utmost to avoid the problem or complaint for the future. Sales must communicate these complaints to every-one in the foundry. The last task is to provide the management level of all updated information of the market. This involves the evolution of the “demand level” as well as the number and activity of the competitors. It is also important to do a “bench marketing”, which reveals the reasons why customers do feel well with deliveries and suppliers. It is also necessary to inform about markets on which the foundry is not working. It can be possible that sleeping or new markets have splendid future expectations. Knowing this information, the foundry can schedule and perform investments and extra activity.

INFORMATION

OFFER

ORDER

CUSTOMER & MARKETINFORMATION

NO ORDER

INFORMATION

MARKETREQUEST FOR

COSTPRICE

CUSTOMER COMPLAINTS

MARKETING INFORMATION

TECHNICAL POSSIBILITIES

QUALITY POSSIBILITIES

CUS TO

MER

COSTPRICE / QUALITY PERFORMANCE

SALES &

MARKETING

QUAL IT Y

CONTROL

ORDER

NO ORDER

COSTPRICE / PRODUCTION TIME

OFFER

FOUNDRY

REQUEST FOR QUOTATION

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3. Features The important feature of sales & marketing is that it belongs to the foundry but works for the customer. It must communicate the feelings of the customer to the foundry and struggle to get the best reaction on it. On the other hand it must show the customer that the foundry, although not performing as it should, has done it utmost or at least knows how to prevent this fact happening again. This department has a job, which seems and is partly conflicting because it has to defend and to work for two different parties. It must have and keep a trustful relation with both parties. The main capabilities are a stable and calm behaviour, whatever the reaction of the opponent is. An angry customer or colleague must get the opportunity to show its feelings in its proper way. This does not mean that everything must be accepted but the sales representative must always be the most calm of all. This attitude will benefit most in the future. This needs to do the job in a very “interesting” way. Having a drink or dinner together, meeting on meetings and or company festivities will be common practice. This must be done in a way that all interesting information, correct information, will be gathered. The method to do this by giving presents, excessive provisions and personal gifts is very controversial at present. This is especially the case if the business will be done in “developing countries”. Working all over the world will ask for local representatives. It can help to feel the correct culture of the customer. But it adds an uncertainty about its knowledge and acting to get information and orders. It also will increase the cost of this department, which is already very high.

4. Conclusion

Sales & Marketing is a very important department, being the connection between customer and foundry and the window to the market. It is mostly a very expensive! It requires very high experienced employees with a highly flexibility in the relation to others. The possibility to bring good as well as bad messages, in an objective but correct way, is necessary. Doing business all over the world will ask for the knowledge of cultures and the ability to adapt to it for a certain extend. It can be interesting to work with local representatives. This will increase the cost. Using not accepted ways to get information and or orders must be avoided! Menu

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SP / FPQ

SERIAL – FIRST PIECE QUALIFICATION 1. Introduction 2. First Piece Qualification Introduction Procedure Importance of pattern 3. Serial Production 4. Corrective Action Qualification 5. Conclusion

1. INTRODUCTION It is not normal practice to start the production of a casting without special care. The casting can be the first to produce or the first part to produce by the foundry with an existing pattern or with a newly made pattern. In all these cases there is definitely a need for a “First Piece Qualification” (FPQ-production). These are the very first three castings produced one after another. After the FPQ-production, all conditions are fixed to produce the casting with the existing working procedures and inspection plans. This production is called the Serial Production (SP-production). It is done according to the MPP mod 0 (manufacturing production plan). If for any reason, the approved MPP is modified (as a preventive or corrective action), the Corrective Action Qualification (CAQ-production) is started. This action will lead to a new MPP, called MPP mod x. All these activities are described in the following text.

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2. FIRST PIECE QUALIFICATION

Introduction The FPQ-production is done to prove that the MPP will lead to castings, which meet the requirements and specifications of the order. It will check that the pattern and working instructions assure that a correct casting is produced (in serial production) at the lowest cost and to the satisfaction of the customer. Procedure This procedure has at least three production runs.

CORES

NDT/DIMENSIONAL INSPECTION

FPQ PRODUCTION

MPPfpq

PATTERN

SPECIFICATIONS

GENERAL

MATERIAL

CASTING

MOULD

ASSEMBLED MOULD

CASTING

MARKING

NDT INSPECTION

DIMENSIONAL INSPECTION

TEMPLATES TEMPLATES

SECOND RUN

THIRD RUN

SERIAL PRODUCTION

TEMPLATE FOR CASTING

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First run Starting from the component drawing and the specifications and the requirements of the order a Manufacturing Process Plan (MPP) is set up. This plan describes the process steps, the work instructions, the pattern and pouring system (included risers and chills) as well as the holding and inspection points. The pattern (layout and dimensions and templates) is the most important tooling and shall be described more in detail in Chapter 2.3 Importance of Pattern. The mould parts and cores are made and assembled. During the assembling the design of templates is figured out. These templates must assure an unique assembly of cores and mould with the narrowest possible tolerance range. The casting is poured and after shot blasting the visual and NDT-inspection is done. It is important to have the pouring system and risers present to help finding the causes of possible non conformity and or scrap. For small and or low cost castings the NDT-inspection can be replaced by a destructive cutting of the casting. Especially the critical areas have to be checked. But a NDT-inspection can complete the picture of the non conformity and will be of help by the inspection during the serial production. According to the result of the NDT-inspection the pouring system, risers, chills and work instructions will be modified. In the worst case even another pattern layout is required. The marking of the casting must be done, starting from the “zero point”, which is also the zero point for the machining. It is important to locate this point in a unique way, available for the moulding department, marking and machining. The result of this dimensional check will be used to correct the dimensions of the pattern and core boxes as well as the connection between each of them. It is impossible to set now the tolerance range because only one measurement is done. The templates to use for the moulding department can be produced now, taking in account the results and experience of the first assembly and dimensions. Second run A new casting is produced using the modified (or not modified) MPP and templates. The NDT-inspection and dimensional inspection must prove that the non conformities are decreased and or removed. Depending of this new result and taking in account that the quality is at least one class better as required by the customer, the MPP and or pattern is modified for the second time. If the results were good, no modification is done.

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Third run The third casting must prove that the production is correct and controlled. The inspection of this casting together with the experience of similar castings and the controllability of the production process will provide information about the tolerance range of the dimensions. It can be that very small corrections can be preferred to assure the best fit. This casting must prove the production for serial production with standard inspection. The templates for the moulding department and the inspection of the castings can be made now. Importance of the pattern The pattern will be responsible for dimensional non conformities, for quality problems due to incorrect and or difficulties by assembling mould and cores and for higher cost of the production. It is the most important tooling for the foundry! To understand these statements, it is necessary to follow the production cycle of a casting. This is shown in the figure on next page. The customer is designing a component, which will establish the final shape, dimensions and material. To choose the must suitable production the order quantity and total need of castings must be estimated. The foundry and designer will create a “casting drawing” using the requirements for quality, surface condition, tolerances and mechanical properties of the material. The casting drawing is transformed in a “pattern drawing”, including pattern layout, material and templates. This will take in account the casting process (production), the engineering (to assure the required quality) and the machining process (dimensions, zero point and tolerance range). The pattern split line, the core-mould connection and the mould-mould connection is designed. The pouring system, risers and chills must be easy to assemble. The location of the identification plate is another item. Two types of templates are used: one to assemble core to core and one to assemble core-assembly to the mould. The templates do start from the “zero point”, which is identical with the point for marking and machining. They have to assure a very narrow dimensional tolerance range and a high controllability of it. These templates belong to the pattern. The templates that are used for the dimensional inspection of the casting do not belong to the pattern.

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CUSTOMER

COMPONENT

D I

MENS I

ONS

SHAPE

MATER I AL

ORDER &

TOTAL QUAN- TITY

CUSTOMER

FOUNDRY

CASTING

QUAL I TY

SUR- FACE CON-

DI- TION

TOLERANCES

HEAT TREATMENT

CAST I NG PROCESS

ABILTY TO ASSEMBLE

CONTROLABILITY

COMPONENT DRAWING

PATTERN LAYOUT & MATERIAL

MACHINING

TYPE

STOCK

CLAMP I NG

ZERO POINT

PATTERN DRAWING

MOULD MATERIAL

MOULD EQUIPMENT

SHRINKAGE

POURING SYSTEM

CORE ASSEMBLY

TEMPLATE

ENGINEERING

NO PATTERN PLATE

PATTERN PLATER I SERS

POU- RING SYS- TEM

MOULD BOXES

CH I LLS

PATTERN UPPER HALF

PATTERN MATERIAL

CORE BOX

PATTERN DRAWING

MOULD

PATTERN DRAFT

CORE BOXTEMPLATE

MOULD LOWER HALF + CORES

IDENTIFICATION PLATE

PATTERN LOWER HALF

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3. SERIAL PRODUCTION The serial production (SP) is the production of the casting after the FPQ-prodution. It is visualised in the figure below. It is done with the MPP-map (Manufacturing Process Plan) and the approved pattern and templates. The MPP must be available for production and inspection at all times! The NDT- and dimensional inspection results will be noted in a quality and dimensional report. The customer will ask for a special measuring and reporting of the “Critical to Quality-dimensions” (CTQ-values). All data are also filed and monitored by the Six Sigma Technique to increase the controllability of the process.

TEMPLATES

SPECIFICATIONS SERIAL PRODUCTION

GENERAL

MATERIAL MPPmod 0

CASTING

NDT/DIMENSIONAL INSPECTION

CASTINGQUALITY REPORT

TEMPLATES ASSEMBLED MOULD

CTQ VALUES

S I X S I G M A T E C H N I Q U E

MATERIAL TEST

NDT TEST

CASTING

MARKING DIMENSIONAL INSPECTION

MOULD

PATTERN

CORES

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4. CORRECTIVE ACTION QUALIFICATION If a non conformity appears during serial production or if the results move towards the limit of the requirements, it is necessary to look for the cause and to do corrective actions. The cause can be related to the MPP-file, the equipment, the material used and or the human activity. These actions can be “preventive” (the result was still in limits) or “corrective” (result was outside limits). This action is called a Corrective Action Qualification (CAQ-production). It is shown in the figure below.

The MPP is modified and a test run is made. If necessary a second and even a third run will be performed. The inspection will cover all aspects involved: those that were changed and those that can be influenced. The final MPP, after the CAQ-proces, is modified and noted as MPP mod x. If the customer modifies dimensions and or adds extra requirements to the specification, it is necessary to agree about the implications: a new FPQ-production, a simplified FPQ-production, a CAQ-production or just continuing the SP-production.

SECOND RUN (if necessary)

TEMPLATE FOR CASTING THIRD RUN (if necessary)

MPP mod x

NDT INSPECTION CASTING

MARKING DIMENSIONAL INSPECTION

MOULD

TEMPLATES ASSEMBLED MOULD TEMPLATES

CASTING

NDT/DIMENSIONAL INSPECTION MODIFICATION

CORES

SPECIFICATIONS CAQ PRODUCTION

GENERAL

MATERIAL MPPmod 0

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5. CONCLUSION

To get the best production of a casting, as well for the customer (complying with all requirements and fulfilling the wishes to a great extend) as for the foundry (lowest cost and highest controlability), it is necessary to follow the described procedure. The production is started with a FPQ-run, followed by the SP-production and interrupted possibly by the CAQ-run. The FPQ-run assures a good serial production concerning quality and dimensions. The SP-production will provide data to increase the controllability of the production and to decrease the cost of production. The CAQ-run will modify the production to increase controlabilty (decrease tolerance range, stabilise quality level…) and to decrease the cost. If the customer is changing requirements, it is necessary to agree about the type of test after modification. It can be FPQ, SP and or CAQ. Menu

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ENVIRONMENT

16. ENVIRONMENT

1. INTRODUCTION 2. FLOW CHART 3. INVENTORY

TOTAL CONSUMPTION PER USER

4. ACTION HOUSEKEEPING PROCESS CONTROL INVESTMENTS SCRAP : REWORK REDUCTION

5. REPORTING EFFIENCY INDEX FINANCIAL REPORT

6. CONCLUSION

1. INTRODUCTION The environment is becoming a very important item. Each society does understand that everyone has to think at the future. It is not allowed to charge or destroy the future for our children. The environment concerns the:

• use of energy • use of raw material • pollution of air • pollution of water • pollution with noise • reclaimable waste • non reclaimable waste.

Each of these items has to be considered sperately. In generally, it is possible to picturise the foundry activity as shown in next picture.

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To monitor these items, which are all Critcal to Quality items, it is necessary to use Process Control. Only then, it is possible to find the best solution during each production step. The possible problems are given in the figure on next page.

PRODUCT

RAW MATERIAL

OTHER MATERIAL

ENERGY

AIR & WATER

RECLAIMABLE WASTE

NON RECLAIMABLE WASTE

AIR POLLUTION

WATER POLLUTION

TEMPERA-TURE INCREASE

NOISE POLLUTION

AD-MINI-

STRA-TION

PRO-DUC-TION

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2. FLOW CHART

ADMINISTRATION

PATTERN SHOPPATTERN

WOOD & TOOLS

MOULDINGSANDDUSTAIR POLLUTIONNOISE POLLUTION

WOOD DUSTRAW MATERIALOTHER MATERIAL

ENERGYAIR

RAW MATERIALOTHER MATERIAL

ENERGYAIR

MOULD

MELTING

METALSLAGAIR POLLUTIONNOISE POLLUTIONTEMPERATURE INCREASEWATER POLLUTION

LIQUID METAL

AIR POLLUTION

CHEMICALS

RAW MATERIALOTHER MATERIAL

ENERGYAIR & WATER

POURING

METALSLAGAIR POLLUTIONTEMPERATURE INCREASE

POURED CASTING

OTHER MATERIALENERGY

AIR

METALSAND

NOISE POLLUTIONTEMPERATURE INCREASEWATER POLLUTION

SHAKE OUT

RAW CASTING

RAW MATERIALOTHER MATERIAL

ENERGYAIR & WATER

AIR POLLUTION

DUST

METAL, TOOLINGSAND

NOISE POLLUTIONAIR POLLUTION

FETTLING

CASTING

OTHER MATERIALENERGY

AIR

DUST

OXIDESREFRACTORY

NOISE POLLUTIONTEMPERATURE INCREASE

HEAT TREATMENT

HT CASTING

RAW MATERIALOTHER MATERIAL

ENERGYAIR & WATER

AIR POLLUTION

TOOLINGCHEMICALS

NOISE POLLUTIONAIR POLLUTION

FINAL INSPECTION

CASTING

OTHER MATERIALENERGY

AIR & WATER

WATER POLUTION

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3. INVENTORY 3.1 Total The inventory must be set up for the total of the foundry. This means that all what is going in and not coming out, is filed in quantities. These quantities can be, depending on the type of item, weight, volume or energy units. The choice of the units is very essential and should be agreed before starting. 3.2 Per user The total consumption will tell us about the subtype of item. The energy inventory tells us if electricity is the most used energy or coal or another. This indicates the subgroup that is most important for actions. But the area involved is also very important. Is it the melting or production of compressed air or another. 4. ACTION The actions can be divides in four groups. These are, not in ranking of importance but alphabetic: housekeeping, investment, process control, scrap/rework reduction. 4.1 Housekeeping This involves the participation of every employee to reduce the consumption of the item. This means that every one will stop non productive use (lightening of a hall without workers). 4.2 Process control This involves the use of good instruction (correct and optimum to have minimum use), good working equipment (maintenance, best performing), best suited materials and the best performance of the employees. Process control measures, check results, propose improvements, apply improvements, re-instruct people, take benefit of experience… 4.3 Investment It can be necessary that excisting equipment must be replaced due to the condition or due to the possibilities. This can only be done if the financing is available. 4.4 Scrap/rework reduction The easiest way to reduce the use of items is to avoid scrap and rework. It is always possible to reduce this figure, whatever it is now.

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5. REPORTING 5.1 Efficiency factor To be able to measure and quantify the result of the program, it is necessary to set “efficiency factors”. These factors must be agreed by all participants and must be related to the environmental and financial result. The facotr will be related to the product unit. But depending on the circonstances, there can be correction factors:

1. Work load of the foundry 2. Type of product 3. Quality level of the product 4. Environmental efforts 5. Safety efforts.

All the factors as well as the calculation must be agreed by all participants. 5.2 Financial report Each company must be as efficient as possible and have a profit. For this reason, the financial consequences must be evaluated and reported to all participants. The profit will be the driving force of the program. Important are the investments, cost to improve and the benefit concerning lower use of the item, less problems and a better delivery and service to the customer. 6. CONCLUSION The environmental consequences of our industrial activity become more important due to real danger of spoiling our environment, due to the shortage of raw materials and due to the reaction of other countries and people, which are influenced by our activity. The best procedure is to have a good “process control”, which enables us to have a clear idea of the activity. It also indicates if some operations that are highly energy consuming, can completely or partly be replaced by others, less consuming. A similar idea about consuming raw material, emissions and production of waste. Every foundry can reduce the environmental consequences. Menu

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Author

17. AUTHOR ir G.D HENDERIECKX ROZENLAAN 1 NL 4551ET SAS VAN GENT THE NETHERLANDS Email: [email protected] Website: www.gietech.be MECHANICAL ENGINEER IN 1970 UNIVERSITY LOUVAIN BELGIUM CAREER (ML: Management level, GM: General Manager) NEDSCHROEF HERENTALS ML PRESSES ALLARD TURNHOUT ML IRON – AND STEEL FOUNDRY BOOMSE METAALWERKEN GM STEEL FOUNDRY TECHNOMET WETTEREN GM HIGH ALLOYED IRON ZEEUWS VLAAMSE GIETERIJ GM IRON – AND STEEL FOUNDRY GIETERIJ MIDDELBURG GM IRON FOUNDRY GIETECH GM FOUNDRIES ALL OVER THE WORLD PUBLICATION GP GIETERIJ PERSPECTIEF DE CONSTRUCTEUR MATERIALEN PARTICIPATION IN PANEL OF SEMINARS CHOICE OF MATERIAL IN VLISSINGEN AND TILBURG MATERIALS IN ANTWERP DAY FOR ENVIRONMENT IN DEN HAAG ENVIRONMENT IN VLISSINGEN TECHNICAL ASSISTANCE FOR TRANSFORMING AN IRON FOUNDRY TO A STEEL FOUNDRY TECHNOMET WETTEREN ZEEUWS VLAAMSE GIETERIJ SAS VAN GENT BEGEMAN HELMOND INTERNATIONAL TRADE IN CASTINGS GE USA, GE FRANCE (Alstom), NUOVO PIGNONE ITALY SULZER GERMANY, SWITZERLAND BHEL INDIA, SUEZ CANAL AUTHORITY EGYPT FLS SCHMIDT DENMARK

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EXPERIENCE WITH MATERIALS LAMELLAR, DUCTILE IRON NIHARD + HIGH CHROMIUM IRON NIRESIST SILICON IRON COQUILLE POURED IRON CARBON STEEL LOW ALLOYED STEEL MANGANESE STEEL WEAR RESISTING CHROMIUM STEEL ROESTVAST EN HITTEBESTENDIG STAAL SIZE UP TO 12 TONNES IN STEEL UP TO 20 TONNES IN IRON PRODUCTION BADGE AND SMALL SERIES PRODUCTION MOULDING WITH CHEMICAL BOUNDED SAND COQUILLE POURING MELTING: CUPOLA-, ELECTRICAL AND ROTARY FURNACES HEAT TREATMENT INDUSTRIES NUCLEAR MACHINE BUILDING DREDGING INDUSTRY CHEMICAL INDUSTRY PRESSES MILLING EQUIPMENT WEAPON INDUSTRY SHIPBUILDING STEEL INDUSTRY GAS TURBINES VALVES NON FERRO MELTING COMPRESSOR TRANSPORT

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