compression & transfer mould design cororate training and planning

COMPRESSION & TRANSFER MOULD DESIGN

CORORATE TRAINING AND PLANNING

CORPORATE TRAINING AND PLANNING

TYPES OF THERMOSET PLASTICS

Phenole formaldehyde (PF)

Urea formaldehyde (UF)

Melamine formaldehyde (MF)

And others


Compression molding of the thermosetting materials has certain advantages as follows :-

• Waste of material in the form of sprue runners and transfer culls is avoided and there is no problem of gate erosion.

• .

• A maximum number of cavities can be used in a given mold base without regard to demands of a sprue and runner system.

• Compression molding is readily adaptable to automatic loading of material and automatic removal of molded articles. Automatic molding is widely used for small items such as wiring device parts and closures.

• In general, compression molds are usually less expensive to build than transfer or injection types.


Limitations of Compression Molding : In the case of very intricately designed articles

containing undercuts, side draws and small holes, the compression method may not be practicable. Articles of 0.35 in thickness compression molding would be slower than transfer slights fins or "flash" are to be expected on molded articles where the mold sections meet.

Articles of polyesters require very careful adherence to all rules for draft; they also require generous ejector areas to avoid fracture on release from the molds. In some cases, compression molding of thermosetting material may be unsatisfactory for production of articles having extremely close dimensional tolerances, especially in multiple cavity molds, particularly relation to non-uniformity of thickness at the parting line of the molded article.


Procedure for Compression Molding :

The sequence of operations constituting the molding cycles is as follows :-

Open the mold ;Eject the molded articles ;Place article in shrink or cooling fixtures when

necessary to maintain close dimensional tolerances (if necessary) ;

Remove all foreign matter and flash from the mold, usually by air blast

Place inserts or other loose mold parts if any ;


Load molding compound (powder or performs, cold or preheated);

Close the heated mold (breathe if necessary);For thermosetting materials, hold under heat and

pressure until cure is completed. Certain materials require cooling under pressure for best control of the dimensions ;

For thermoplastic materials hold under pressure and cool to harden the articles.

The temperature of the mold and the pressure applied are extremely important and it is advisable to follow the recommendations of the manufacturer for each grade of material used.


There are five very important variables in the compression molding of thermosetting materials which determine the pressure required to produce the best molding in the shortest length of time. These are as follows :-

1. Design of the article to be produced : projected area and depth wall thickness obstruction to vertical flow (such as pins, louvers and

sharp corners) 2. Speed of press in closing ; use of slow or fast acting self contained press use of fast acting press served by hydraulic line

accumulator system capacity of accumulator to maintain constant follow

up of pressure on material


3. Plasticity of material ; degree and type of preheating density of charge (perform or powder) position of charge in cavity mobility of resin under pressure type of filler (wood flour, cotton flock, macerated fabric,

asbestos, glass or mica). 4. Over all temperature of mold ; temperature variations within cavity and force of mold 5. Surface condition of mold cavity and force ; highly polished chrome plated surface polished steel poor polish (chromium plating worn ; pits, gouges and nicks) Molding pressures required for most thermosetting

materials follow the pattern established for phenolic materials.


Compression MouldsCompression moulds are made of High Carbon high

Chromium H11, H 13 Hot die Steels. It consists of a lower cavity or cavities also known as Bottom force,& core or Punch also called as an upper force . The molding portions of the molds are hardened and highly polished.

The two halves of the mold are mounted between the platens of a hydraulic compression press. The weighted raw material or Charge is placed in the cavity of heated mould in Powder form or performs. Both the mould halves are closed by the press, the top force causes the Plastics material to flow in the mold. The material is compressed into the shape by the application of heat and pressure which causes a chemical reaction in the material .The material is chemically cross linked or set or cured into the shape of the required Product.


Types of Compression Moulds

• Hand Moulds• Semi–automatic moulds• Automatic moulds.

For most economic production moulds are made from High grade HDS i.e, H 11,or H 13 steels which are hardened and polished.


Hand Compression Mould

These moulds are used for smaller production runs or Prototypes, experimental jobs that require minimum mold cost & Parts having Open Tolerances. These

moulds are used advantageously for complex Parts incorporating number of loose pull pins and

wedges. A Hand Mold weights less than 10 Kgs for easy manual handling. As all the mould operations

are manual, Automation is not possible. Hence Hand Moulds are slow in operation which requires longer cycle time and is labour intensive, adding to

Production cost as compared to other type of moulds Moreover, the molds are more easily

damaged by misalignment and mishandling etc which may result from Improper mould operation

and closing of the mold.


1.Top force ret. Plate2. Bottom force plate3. Bottom force

4. Top force5. Guide pillar

6. Guide bush7. Bottom force insert


Semi-automatic Compression MouldSemi-automatic moulds are fastened in the

press for the duration of the run. The press-operator automatically releases the mould piece as the press opens, thus permitting ready removal, semi-automatic moulds are used for mass production of jobs.

While operating semi-automatic moulds the operator is required for only a brief period during each molding cycle. Almost all Parts with limited design complexities can be produced by semi-automatic compression molds.


Classification of Semi automatic Moulds.

1. Semi-automatic Open Flash Mould

2. Semi-automatic Fully Positive Mould

3. Semi-automatic Landed Positive Mould

4. Semi-automatic Semi Position Mould


HEAT SOURCE


Automatic Mould In principle Automatic Moulds are similar to semi-

automatic moulds. They have additional mechanical features, which serve to perform all operations automatically in sequence, when used in an automatic press. The Plastics material is measured & charged in to the mould from a hopper by a automation device that are set in a motion by a master timer. The timer operates the valve or linkage device to close the press and open it again, when the molding cycle is completed. Mould opens & subsequently Ejector pins demoulds the molded piece from the mold cavity or core so that it may be picked or blown in to a receiving pile by external device.


Automatic moulds are used when automatic presses are available. These moulds are generally expensive than semi-automatic moulds but their operational cost is considerably low.Automatic Moulds eliminates human errors but there may be difficult to keep in adjustment for certain jobs & from maintenance standpoint.

Automatic Moulds are best adopted for jobs requiring better accuracy , stringent Tolerances & for mass Production.

1. OPEN FLASH MOULD

2. LANDED PLUNGER MOULD

3. POSITIVE MOULD

4. SEMI POSITIVE MOULD


CALCULATION OF LOADING CHAMBER DEPTH

D = VT – VC

AWhere,

D – Depth of loading space from top of cavity to pinch-off land

VC - Volume of actual cavity space (cm3)

VT - Total volume of loose powder (cm3)

A – Projected area of the loading chamber (cm2)

Where,

V – Total volume of part including flash factor Around 10 to 20%.

This is the standard Practice adapted to calculate the depth of loading chamber .


DESIGN OF THE MOULD CAVITY

Generally Moulds are designed ruggedly to withstand Thrusts, Pressures, loads, stress from mechanical standpoint, hence the mould cavity should have adequate dimensions to withstand the clamping pressure & also to prevent distortion within the specified tolerance limits of deformation. Cavity Strength Calculation


For Rectangle Cavity

In the case of larger moulds the distortion tendency due to Internal pressure should be considerd & in case small distortion takes place, the effect is not determinant, where the moulds are built in sections & fitted into a bolster, then distortion at the core, of the open side may be found using the following formula.


FLASH THICKNESS ALLOWANCES

Allowances for flash thickness in compression moulds, using thermosetting compounds are:-Rag-filled high impact compound - 0.25mmCotton – flock compounds in large molds - 0.2mmWood – flour compounds in small molds - 0.1mm

All other moulds are for all other compounds allow 0.13mm (except as previously noted)

Because of the flash thickness that we are considering in the mould design the depth of cavity become:

Depth of Cavity = Minimum dimension of moulding + Shrinkage of compound

The flash thickness adds to the total thickness of the part and this thickness must be subtracted from the basic cavity depth in order that the finished Part may have the desired wall thickness.


Technological Determination of the Number of Cavities OR Impressions in Compression Mold

During calculation of the number of cavities or impressions by technological method for multi-cavity moulds, the following parameters should be considered. On the machine side we have to consider – available machine clamping force, and size of the platen.

For the moulding materials we have to consider the compression pressure of the material and for the moulding the projected area should be taken into account during calculation.

The calculation as follows:Claming force (kgf) = Projected area of the moulding (cm2) x

Compression pressure of the plasticmaterial kgf/cm2


The projected area can vary depending on the size of the component as well as on the design of cavity or loading chamber and the compression pressure also can vary based on the type of plastics materials.

For example, in a vertical flash or positive type of mold, there is no need of horizontal land. But in the case of horizontal flash type of mold the flash width should be taken in to account for the determination of the projected area.

So the projected area in the case of vertical flash type is same as the projected area of the component. But, in the case of horizontal Flash type, 20% of the projected area of the component should be taken into account for the flash. Therefore, the actual projected area is -

1.2 x Projected Area of the component.


The compression pressure must be regulated in order to produce satisfactory parts economically. Pressure needed to mold a particular article depends on the flow characteristics of the material, the cavity depth and the projected are of the piece part. Generally it is recommended that minimum molding pressure of 240 kg/cm2 of projected area be used. However, in practice, about 300 kg/cm2 of projected area is used to compensate for any variables that may be encountered.

After finding the clamping force required for one impression, the number of impressions can be determined from the actual clamping force available for a particular machine –

i.e. No. of Impression = Clamping force available on the machinepossible Clamping force required for an impression

Using this Technical formula, the number of impressions can be determined.


Heat Treatment of mould parts

Hardening and TemperingDimensional & Shape stabilitySurface treatmentTesting of mechanical propertiesStress relieveMould polishing


ADVANTAGES OF COMPRESSION MOULD OVER TRANSFER MOULD :-

Waste of material in the form of sprue runners and transfer culls is avoided and there is no problem of gate erosion.

Internal stress in the molded article is minimized by the shorter and multi directional flow of the material under pressure in the mold cavity. In the case of high impact types with reinforcing fibers, maximum impact strength is gained. This results because reinforcing fibers are not broken up as is the case when forced through runners and gates in injection molding.

A maximum number of cavities can be used in a given mold base without regard to demands of a sprue and runner system.


• Compression molding is readily adaptable to automatic loading of material and automatic removal of molded articles. Automatic molding is widely used for small items such as wiring device parts and closures.

• This technique is useful for thin wall parts that must not warp and must retain dimensions. Parts with wall thickness as thin 0.025 in are molded, however, a minimum wall thickness of 0.060 in is usually recommended.

• For parts weighing more than 3 lb, compression molding is recommended since transfer or screw injection equipment would be very expensive for larger parts.

• For high impact, fluffy materials, compression molding is normally recommended because of the difficulty in feeding the molding compound from a hopper to the press or performer.

In general, compression molds are usually less expensive to build than transfer or injection types.


Compression Mould Design Tips

When designing a mould for the compression molded part, it is important to keep in mind that the goal is to produce quality parts in as short a cycle as possible with a minimum of scrap. To achieve these goals, you will need a mold that has a uniform mold temperature, and is properly vented

MOULD HEATING SYSTEM:-A uniform mold temperature means that the temperature of

each half of the mold is the same (within 3° C ) for all locations when the mold is heated by oil or steam. Molds that are heated with electric cartridge heaters can vary by as much as 6°C. A mold with a uniform temperature, will fill easier and produce parts with less warpage, improved dimensional stability and a uniform surface appearance. Achieving a uniform mold temperature is dependent on your method of mold heating.


HEAT REQUREMENTS & HEAT CAPACITY:-To determine the amount of wattage needed to

heat a mold the use of the following formula might be helpful: 1 1/4 kilowatts for every 45kg (100 pounds )of mold steel. (Note this formula will normally allow the mold to be heated to molding temperature in 1 to 2 hours) This does not include the ejector housing in the weight for the mold but it does include the “A” & “B” plates and the support plates behind the “A” & “B” plates.


Locating a heater on the center line on the mold is not recommended, because the center of the mold is normally hot enough without any additional heat. Typically, the cartridge heaters are located in the support plates at a distance between heaters of 65mm. There should be a minimum of one thermocouple to control each half of the mold. In larger molds, it is recommended to have more than one thermocouple in each mold half. This will result in better control and more uniform mold temperatures. The thermocouples must be located in the “A” & “B” plates, between two heaters if possible & at a distance of 32mm to 38mm from the closest cartridge heater. This distance is to be measured from the edge of the thermal couple hole to the edge of the cartridge heater hole.


The distance from the thermal couple to the heater is important because a heater that is too close will cause the thermocouple hole to the edge of the cartridge heater hole. The distance from the thermal couple to the heater is important because a heater that is too close will cause the thermocouple to turn off the heat before the mold is at temperature. A heater that is too far away from the thermal couple will result in a mold that over heats and then gets too cool. Likewise, it is not a good practice to position a thermal couple so it senses the external surface temperature of the mold. If possible, it should be located 38mm to 51mm inside the mold, since the temperature taken there, is less susceptible to outside influences and therefore more stable.


TRANSFER MOULD DESIGN

Transfer Molding material is used when the molding dimensions, shape or configuration, impose conditions which cannot be met by compression molding. Two of the main conditions imposed by the molded component which necessitate the use of the transfer molding method are:

In case where the wall thickness & dimensions of the molding is critical and has to be held to a close tolerance.

Where the shape of the molding necessitates the use of thin, weak sections of metal or thin small diameter pins, which could be damaged by the force created by the initial flow of material when using the compression method.


TRANSFER POT CALCULATIONS

The dimensions of the pot, if it is round or square can be calculated once the area is known:-

Total area of Pot Ap

= Total projected area of cavities, runners and sprue + 25 – 30% of total projected area.

Volume of Pot Vp

= Total volume of all the piece parts, the runners and the sprue plus approximate volume of a small amount for a 0.5 to 1mm thick cull multiplied by Bulk factor of the compound.

Depth of Pot = Vp

Ap

CORPORATE TRAINING AND PLANNINGCLOSED POSITION

CORPORATE TRAINING AND PLANNINGRECOMMENDED DESIGN OF LOWER PLUNGER


FACTORS THAT INFLUENCE THERMOSET MOLDING

Three important factors that must be considered in thermo set molding are:

a) Temperature,

b) Pressure, and

c) Cure Time


TEMPERATURE

Thermosetting Plastics materials must be heated to approximately 170 to 190C for optimum cure.

Temperature for molding various materials can be determined by getting the information from the Material manufacturer.

Higher temperature may degrade some of the physical properties , electrical characteristics & mechanical Properties of the material. Particularly in transfer molding, may cause the material precure before the cavity is completely filled.

High temperatures may also cause blisters and burn Marks on the finished articles.

Low Processing Temperatures will not allow the material to flow properly and result in incompletely cured parts with poor consistency, thus reducing the productivity of the cycle.


There is Normally an optimum temperature which produces the best flow characteristics for the particular material and cavity Design.

The Optimum mold temperature not only varies with the material being used, but also varies with the geometry of the molded articles, and whether loose powder or pre-heated preforms are used.

Because plastics are generally good heat insulating materials, preheating of the charge is often used to shorten the moulding cycle time . Pre-heat temperature are between 70C and 130C, higher temperature are possible when heat is more rapidly transferred to the material.


Pre-heated material generally flows more rapidly during the actual molding process and because the material starts at an elevated temperature, the time of complete the cure in the mold cavity is shortened, generally yielding a more economical overall cycle.

Another source of heat input to the plastic during the molding process is from frictional or shear heat during the closing of the mold. In the case of compression molding, the material is forced in to flow by the closing action of the mould. This flow may be at fairly high localized velocities, which impart a certain amount of frictional heat energy to the plastic.


In transfer molding, the frictional heat is even more pronounced as the material is forced along feed system and through relatively small gates leading to the cavities. The amount of frictional heat added to the material in transfer molding is dependent on the speed of the plunger advance, the size and configuration of runners and gates and the surface finish of the mold. It must be taken in to consideration when using relatively heat-sensitive materials. Mold temperatures must be maintained with ± 3C for the best results.


PRESSUREMoulding with thermosetting plastics requires

greater pressure for two basic reasons:a) To ensure that the plastic fills all of the cavity and has relatively uniform density throughout. (Pressure causes the cavity to fill and resists the tendency of internal gases to form voids or gas pockets, pressure must of course be sufficient to overcome resistance of the plastic to flow).b) To ensure better heat transfer to the material (Higher pressure produces a higher density, which generally means faster thermal conductivity.


In compression Moulding a pressure of 210 kg/cm2 has been found suitable for phenolic materials. Material manufacturers recommend that 160 kg/cm2 is sufficient. But normally this pressure is low and it is sufficient for easy flow materials and a simple uncomplicated shallow moulded Parts. Moulding Pressue should be optimised based on material type, type & level of filler loading, Part Design, mould Design & moulding conditions.

For a medium flow material and where there is a number of average sized cutouts( Openings), cores and pins in the molding cavity where the material has to flow in to small intricacies and orifices and to produce a good quality packed and dense moulding, a pressure of 210 kg/cm2 or above is necessary.


Also the deeper the moulding cavity, the more Moulding pressure is required and a fairly simple rule is to add approximately 20 kg/cm2 per cm of depth in excess of 2.54 cm of cavity depth (maximum up to 30 cm depth) for the material without pre-heat. For the material with pre-heat, the pressure approximately 70 kg/cm2 or above, is required and for deeper moulding a pressure of 7 kg/cm2 per cm of depth in excess of 2.54 cm is added.

For molding urea and melamine material, pressures of 2 times that needed for phenolic material are necessary (i.e.) approximately 320 kg/cm2 per cm of depth in excess of 2.54 cm is added for material without pre-heat.


For transfer moulding, generally pressure of 3 times the magnitude of those required for compression molding are required. Depending upon the configuration of the moulding, the design of mould (eg. Whether direct sprue type or that employing a runner system) and the flow properties of the grade of material used. It is possible some times to mould with a pressure of between 530 kg/cm2 – 560 kg/cm2 but in general, a pressure 630 kg/cm2 and above is required for phenolic material, the pressure referred to here being that applied to the powder material in the transfer chamber ( for Material without pre-heat)


CURE TIME

The time required to harden thermosetting materials to partial or complete polymerization is called the cure-time. Many moulders produce parts that are hard enough, blister free and apparently cured, yet the polymerization of the resin system is not complete and a post bake cycle may be required to optimize properties.

The curing time variables are as follows:Material TemperatureMold TemperatureMaterial Type Part Cross-Sectional AreaMoulding PressureMaterial Preheat & use of Preform


MATERIAL TEMPERATURE

To obtain minimum cure time, the material must be at the maximum Preheated temperature when it is loaded into the moulds.

Material may be pre-heated by using infra-red lamps, radio frequency pre-heaters and extrudates formed from screw feed material in a heated barrel.


MOULD TEMPERATURE

The designer must have good knowledge of the recommended mould temperature for each type of the Plastics material and he must arrive at the maximum mould temperature and cycle, that will produce quality parts at the shortest overall cycle.


CROSS-SECTIONAL AREA

The Cross-sectional Area or wall thickness will determine the cure time required to produce the part. A cross section upto 2 – 3 mm thick will cure in few seconds, where as enhanced wall sections may require few minutes. Parts having thickness or cross-sectional areas in excess of 9 – 13 mm are difficult to mould by compression moulding. In order to establish minimum cure cycles; transfer or injection methods of moulding will be better.


DEGREE OF CURE

Determining the degree of cure, regardless of the moulding process used, are vitally important in establishing the following important factors:Maximum moulded densityProper moulded part rigidityThe optimum point for moulded part ejectionDimensional stability of the moulded parts.


MOULD HEATING TECHNIQUES

Electrical HeatingSteam HeatingOil HeatingHot water GAS etc


ELECTRICAL ENERGY REQUIREMENT TO HEAT THE MOLD

Empirical = 30-40 W/kg of mould By calculation – The heat required to raise the mold to operating

temperature is given by, QR = Q1

+ Q2 + Q3

+ Q4

While the heat required to maintain the mold at operating temperature and to provide heat for curing plastic material is given by , Q0

= Q1 + Q2

+ Q3 + Q5

Where, Q1= Conduction losses through asbestos insulation from mold to

platens (Btu/h or cal/h – (a)Q2

= radiation losses from mold faces (Btu/h or cal/h – (b)Q3

= convection losses from mold faces (Btu/h or cal/h) – (c)Q4

= heat required to raise temperature of metal to operatingtemperature (Btu or cal) – (d)

Q5 = heat required for heating plastic material (Btu/h or cal/h) – (e)


Q1 = kA1T1

LWhere k = thermal conductivity of

asbestos/ hylem insulation (tps or cgs units)

A1= total area of mold top and bottom faces in contact insulation (ft2 or cm2)

L = total thickness of top and bottom asbestos insulation (ft2 or cm2)

T1 = temperature difference between mould and press (deg F or deg C)


Q2 = 1.38 X 10-9 (T2 + 460)4 X A2

Where 1.38 x 10-9 (T2 + 460)4 is the modified Stefan’s constant for a rough finished tool surface= temperature of mould (deg F or deg C)= area of exposed tool faces (ft2 or cm2)

During initial heating up, the tool is normally closed and hence normally the radiation losses are from the vertical faces. In operation, however, the horizontal faces are exposed for a long time and hence an additional allowance must be made when determining the heat requirements during moulding.


The heat lost by convention from the vertical faces is

Q3 = (0.7 + T3) T3 A2

_ 375

Where T3 = temperature difference between tool and surrounding air (deg F or deg C)


The heat lost by convention from horizontal faces lying upwards is

Q3’ = (0.7 + T3) T3 x 1.1 x A3

375 The heat lost by convention from horizontal faces lying

downwards is

Q3” = (0.7 + T3) T3 x A4

375 x 2

Where A3 = area of mould face lying upwards (ft2 or cm2); and

A4 = Area of mould face lying downwards (ft2 or cm2)


The initial heat required to raise the tool from room temperature to operating temperature, considering the heat losses listed, is

Q4 = m1 X Cp1 x T4

Where m1 = weight of mould (lb or kg)

Cp1 = specific heat capacity of mould steel

T4 = temperature rise from room

temperature to operating temperature

(deg F or deg C)


Heat required to cure the moulding material is given by

Q5 = m2 X Cp2 x T5

Where m2 = weight of mould (lb/h or kg/h)

Cp2 = specific heat capacity of moulding material

T5 = temperature rise required from room (or pre-heat temperature) to moulding temperature

(deg F or deg C)


Dimensions of Steam and Hot Water Heating

The determination of the heat balance of steam and hot water heating, i.e., the exact determination of the length and dia of the pipe required for supplying the given heat & heat losses, involves as extremely complex calculation process.


The clearance between the force and cavity mold halves on the vertical wall as is shown in the sketch should be 0.001” to 0.002” per side except for mold for BMC which should be 0.002” to 0.003”. With this tight of a mold, it will be necessary to add vents to this wall in order for the mold to close. These vents should be located near the last places to fill and should start out being 0.005” deep and extending up the entire length of the wall. When molding PLENCO BMC materials, it is very important to maintain this clearance between the mold halves. If this clearance becomes to large, it will not be possible to hold the internal cavity pressures causing scrap rates to increase and part appearance to suffer.


General Mold Design Check list

All mold components contacted by the molding compound-runners, gates, cavities, land areas-should be made of through-hardened tool steels, hardened to 65 to 68 on the Rock-well C scale, highly polished, and hard chrome plated.

Because most thermoset compounds are slightly soft at the time of ejection from cavities, ejector pins should have an adequate correctional area to minimize the possibility of distorting or puncturing the molded plastic at this point in the cycle.


In automatic molds, it is vital to ensure, with part design, undercuts, or hold-down pins, that the molded parts, during mold opening, consistently remain in the desired half of the mold, so that when the parts and the runner system are ejected, the comb or extractor will always "find" them and effect positive removal.

Flash removal from the mold, each cycle is critical for successful automatic moulding (the “flash-free molds” are myths). Every effort must be made to have the flash ejected with the molded part. An air blast, directed appropriately to cavities and land areas each molding cycle when the mold or press to further ensure the absence of flash each cycle.


Should flash being to accumulate in or on the mold, the mold should be cleaned, polished, and/or repaired.

Molds should be of uniform temperature in the cavities, and should have adequate heating capacity to ensure maintenance of the desired temperature despite continual heat extraction by the relatively cooler molding compound each cycle.


Temperature sensors and heating cartridges must be judiciously placed to provide this uniformity of temperature. Insulating blankets may prove helpful to minimize mold heat losses and variations due to local air currents around molds and presses.

to minimize local temperature variations in large molds, heating cartridges often are grouped in zones, with each zone having is own temperature controller and sensor. Sensors should be positioned with ¼ inch of heating cartridge to prevent significant temperature over swings.


It also is prudent to provide for a “mold over temp” sensor, which will cut off power to the heating cartridges whenever it senses a mold temperature more than a few degree over the desired mold temperature.

Excessive mold temperature not only will results in reject parts, but also may anneal the mold steels and warp critical mold components.

An adequate moulding press should be used considering the required tonnage capacity of mould. Over tonnage application may damage the mould.

For a transfer mould, the pot dimension must be adequate to the required volume of loose power for plastic material feeding.


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compression & transfer mould design cororate training and planning

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