casting materials
TRANSCRIPT
Casting materials
We have total consistency to reply customers’ needs and expectation on the base of our integrated production process from designing to mass production only in our company.
Casting materialWe provide wide and various products by our casting and processing technology.
FC Material Parts
FCD Material Parts
FCV Material Parts
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Brake Disk materials
FC150HCTensile Strength ≥ 150MPa
Materials that deposit flake graphite in the base, raise thermal conductivity, reduce the deformation and brake squeal by using high damping capacity.
FC220PTensile Strength ≥ 220MPa
Materials whose base tissue is compounded with alloy such as Cu, Cr improved in corrosion resistance.
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Ductile cast
FCD450It has superiority of both tensile strength and growth to JIS Standard.
FCD550It has higher growth ratio than JIS Standard in the same tensile strength.
FCV350It has sliding properties close to FC Materials and high tensile strength.
Mechanical properties of grade SC37Technological properties of grade SC37Hardness and heat treatment specification of grade SC37
Annealing hardness
HBS
Cold pull hardness
HBS
Preheating temperature℃
Quenching temperature℃ Holding timemin
Hardening medium
Temper temperature℃
After tempering hardness≥HRCsalt-bath
furnacecontrolled
atmosphere furnace235 262 788 1191 1204 5～15 air cooling 522 60
Steel plate/Sheetthickness / mm
σbMPa
σs≥/MPa
δSamples from the standard for 50 mm (2 in)
180 ° of cold bending testlongitudinal horizontal
Hot-rolled/Cold rolling:5 - 150 520 415 16～18 2a 3.5aNote:(1) listed in the table apex diameter (d), to steel thickness (a) multiples said.(2) in the ASTM A6 standard specified scope can meet any additional conditions.(3) from the standard for 50 mm (2 in).Mechanical properties Mechanische EigenschaftenCaracteristiques mecaniquesReH Minimum yield strength / Mindestwert der oberen Streckgrenze / Limite d’elasticite minimale Rm Tensile strength / Zugfestigkeit / Resistance a la traction A Minimum elongation / Mindestwert der Bruchdehnung / Allongement minimal
J Notch impact test / Kerbschlagbiegeversuch / Essai de flexion par chocSC37 steel description:Step Shaft: steel plate/sheet,coil,round bar,flat bar,tube/pipe,Profiled forgingsSC37 steel Specifications or Size:
Round bar:Diameter : 1mm-2000mmSquare bar:Size: 50mm * 50mm-600mm *600mmPlate steel/flat bar:Size: Thickness: 0.1mm-800mm Width: 10mm to 1500mmTube/pipe: Size: OD: 6-219mm WT: 1-35 mm.Cold-rolled sheet: Thickness: 2-5mm Width:1000mm Length: 2000mmHot-rolled sheet: Thickness:6-80mm Width: 210-610mmLength: We can supply any length based on the customer's requirement.Forging/hot rolling/ extrusion of steel.Forging: Shafts with flanks/pipes/tubes/slugs/donuts/cubes/other shapesFinished goods condition: hot forging/hot rolling + annealing/normalizing + tempering/quenching + tempering/any conditions based on the customer's requirementSurface conditions: scaled (hot working finish)/ground/rough machining/fine machining/based on the customer's requirementFurnaces for metallurgical processing: electrode arc + LF/VD/VOD/ESR/Vacuum consumable electrode.Ultrasonic inspection: 100% ultrasonic inspection for any inperfections or based on the customer's requirement.UTS according to SEP 1921 C/c,D/d,E/e;A388 or GB/T 6402Excellent service for all kinds of industries, with advantages of technologies, equipment and price.We serve you with our honesty, integrity, and professionality.
C≤
Si≤
Mn≤
P≤
S≤
Cr Ni
0.2 agreed agreed 0.04 0.04Mo Al Cu Nb Ti V CeN Co Pb B Other
Contact sales:TEL:+86-816-3646575Mobile:+86-15386639257E-mail: [email protected]
Hot keywords:SC37
Mechanical properties of grade SC49Technological properties of grade SC49Hardness and heat treatment specification of grade SC49
Annealing
hardness
HBS
Cold pull
hardness
HBS
Preheating
temperature℃Quenching temperature℃ Holding
time
min
Hardening
medium
Temper
temperature℃After tempering
hardness
≥HRCsalt-bath furnace
controlled atmosphere furnace
235 262 788 1191 1204 5～15 air cooling 522 60
Steel plate/Sheet
thickness / mm
σb
MPa
σs
≥/MPa
δ
Samples from the standard for 50 mm (2 in)
180 ° of cold bending testlongitudinal horizontal
Hot-rolled/Cold rolling:5 - 150 520 415 16～18 2a 3.5aNote:(1) listed in the table apex diameter (d), to steel thickness (a) multiples said.(2) in the ASTM A6 standard specified scope can meet any additional conditions.(3) from the standard for 50 mm (2 in).Mechanical properties Mechanische Eigenschaften
Caracteristiques mecaniquesReH Minimum yield strength / Mindestwert der oberen Streckgrenze / Limite d’elasticite minimale Rm Tensile strength / Zugfestigkeit / Resistance a la traction A Minimum elongation / Mindestwert der Bruchdehnung / Allongement minimal J Notch impact test / Kerbschlagbiegeversuch / Essai de flexion par chocSC49 steel description:Step Shaft: steel plate/sheet,coil,round bar,flat bar,tube/pipe,Profiled forgingsSC49 steel Specifications or Size:
Round bar:Diameter : 1mm-2000mmSquare bar:Size: 50mm * 50mm-600mm *600mmPlate steel/flat bar:Size: Thickness: 0.1mm-800mm Width: 10mm to 1500mmTube/pipe: Size: OD: 6-219mm WT: 1-35 mm.Cold-rolled sheet: Thickness: 2-5mm Width:1000mm Length: 2000mmHot-rolled sheet: Thickness:6-80mm Width: 210-610mmLength: We can supply any length based on the customer's requirement.Forging/hot rolling/ extrusion of steel.Forging: Shafts with flanks/pipes/tubes/slugs/donuts/cubes/other shapesFinished goods condition: hot forging/hot rolling + annealing/normalizing + tempering/quenching + tempering/any conditions based on the customer's requirementSurface conditions: scaled (hot working finish)/ground/rough machining/fine machining/based on the customer's requirementFurnaces for metallurgical processing: electrode arc + LF/VD/VOD/ESR/Vacuum consumable electrode.Ultrasonic inspection: 100% ultrasonic inspection for any inperfections or based on the customer's requirement.UTS according to SEP 1921 C/c,D/d,E/e;A388 or GB/T 6402Excellent service for all kinds of industries, with advantages of technologies, equipment and price.We serve you with our honesty, integrity, and professionality.
C≤
Si≤
Mn≤
P≤
S≤ Cr Ni
0.4 agreed agreed 0.04 0.04
Mo Al Cu Nb Ti V Ce
N Co Pb B Other
Contact sales:TEL:+86-816-3646575Mobile:+86-15386639257E-mail: [email protected]
DATA TABLE FOR:STEEL GRADES:MOULD STEEL:SC360Chemical composition % of the ladle analysis of grade SC360Mechanical properties of grade SC360Technological properties of grade SC360Hardness and heat treatment specification of grade SC360
Annealing
hardness
HBS
Cold pull
hardness
HBS
Preheating
temperature℃Quenching temperature℃ Holding
time
min
Hardening
medium
Temper
temperature℃After tempering
hardness
≥HRCsalt-bath furnace
controlled atmosphere furnace
235 262 788 1191 1204 5～15 air cooling 522 60
Steel plate/Sheet
thickness / mm
σb
MPa
σs
≥/MPa
δ
Samples from the standard for 50 mm (2 in)
180 ° of cold bending test
longitudinal horizontal
Hot-rolled/Cold rolling:5 - 150 520 415 16～18 2a 3.5a
Note:(1) listed in the table apex diameter (d), to steel thickness (a) multiples said.(2) in the ASTM A6 standard specified scope can meet any additional conditions.(3) from the standard for 50 mm (2 in).Mechanical properties Mechanische EigenschaftenCaracteristiques mecaniquesReH Minimum yield strength / Mindestwert der oberen Streckgrenze / Limite d’elasticite minimale Rm Tensile strength / Zugfestigkeit / Resistance a la traction A Minimum elongation / Mindestwert der Bruchdehnung / Allongement minimal J Notch impact test / Kerbschlagbiegeversuch / Essai de flexion par choc
SC360 steel description:Step Shaft: steel plate/sheet,coil,round bar,flat bar,tube/pipe,Profiled forgingsSC360 steel Specifications or Size:
Round bar:Diameter : 1mm-2000mmSquare bar:Size: 50mm * 50mm-600mm *600mmPlate steel/flat bar:Size: Thickness: 0.1mm-800mm Width: 10mm to 1500mmTube/pipe: Size: OD: 6-219mm WT: 1-35 mm.Cold-rolled sheet: Thickness: 2-5mm Width:1000mm Length: 2000mmHot-rolled sheet: Thickness:6-80mm Width: 210-610mmLength: We can supply any length based on the customer's requirement.Forging/hot rolling/ extrusion of steel.Forging: Shafts with flanks/pipes/tubes/slugs/donuts/cubes/other shapesFinished goods condition: hot forging/hot rolling + annealing/normalizing + tempering/quenching + tempering/any conditions based on the customer's requirementSurface conditions: scaled (hot working finish)/ground/rough machining/fine machining/based on the customer's requirementFurnaces for metallurgical processing: electrode arc + LF/VD/VOD/ESR/Vacuum consumable electrode.Ultrasonic inspection: 100% ultrasonic inspection for any inperfections or based on the customer's requirement.UTS according to SEP 1921 C/c,D/d,E/e;A388 or GB/T 6402Excellent service for all kinds of industries, with advantages of technologies, equipment and price.We serve you with our honesty, integrity, and professionality.
C≤
Si≤
Mn≤
P≤
S≤ Cr
0.2 agreed agreed 0.04 0.04
Mo Al Cu Nb Ti V
N Co Pb B Other
Contact sales: TEL:+86-816-3646575 Mobile:+86-15386639257 E-mail: [email protected]
Hot keywords:SC360
Chapter 1. Basic Machining and Tips
Metal Materials
Materials
There are many different material types to choose from when undertaking a project. For the purposes of our discussion, the materials are grouped roughly into two categories, these being "Non-metallic" and Metallic". In respect to metallic materials these are then subsequently grouped into two groups being ferrous and non-ferrous. Each of the materials has their own characteristics and requires different machining techniques. Careful consideration needs to be given to the correct material selection for its application. (Definition: Ferrous as in containing Iron, e.g steel - Non-ferrous as in not containing Iron e.g aluminium, copper) A simple test for ferrous/non-ferrous materials is to use magnet as a magnet will sick to ferrous materials due to its iron content.
Aluminium Alloy
There are many kinds of Alloys to choose from but often, Aluminium is chosen as it is lightweight (about 2700 kg/m3 density), it is comparatively soft and its process-ability is good. From a machining viewpoint pure aluminium (JIS A1000) greatly differs from Al-Cu alloy (JIS A2000) .
Pure aluminium is easy to bend but it is difficult to process as it is too soft and easily clogs cutting tools. On the other hand, the Al-Cu alloy, such as A2011 or A2017 (called duralumin) is easy to handle and cut with several of the grades having strength similar to that of steel. However, one of the drawbacks of aluminium is that it is difficult to weld, solder and bend.
It is very difficult to distinguish between the pure aluminum, the Al-Cu alloy and etc. When they are cutting with a machine, we may recognize the material.
Fig.1, Aluminum Alloy (JIS A2017)
Stainless Steel
A typical stain less steel is JIS SUS304. The benefits of stainless steel is that it has high strength, great heat-resistance, and and it resists staining e.g rust. Due to its high resistance to heat it makes an ideal material for mechanical parts that are subjected to heating such as a heater of a Stirling engine. Also, due to the materials resistance to rusting, it is ideal for use where it is exposed to water. Other examples of its use is in drive shafts where both strength and corrosion resistance is needed.
Stainless Steel tends to be a bit sticky in respect to cutting and machining and as it is a relatively hard material it tends to shorten the life of the cutting tools being used. Such cutting tools need to be sharpened often particularly in prolonged cutting operations. Stainless Steel can usually be identified by its glossy silver colour.
Fig.2, Stainless Steel (JIS SUS304)
Carbon Steel
Typical carbon steel materials are JIS S45C and JIS SS400. They are very cheap, excelling in weldability, and they can be subjected to various heat treatments. Since many machine tools are designed to cut mild steel material, it is very rare to encounter problems while machining.
I hardly use mild steel apart from cases where welding is required as I mostly make experimental models as therefore issues such as low manufacturing costs are not a consideration in the work that I do.
Generally, mild steel has a black surface and this surface is very hard, if possible, this surface should be left intact as it offers additional protection.
Fig.3, Carbon Steel (JIS S45C)
Brass
Brass is an alloy which is made from a combination of copper and zinc as the main ingredients. In compared with carbon steel or stainless steel, the machine-ability of brass is good, and it also has good soldering properties.
Brass is very heavy due to its high density so it is ideal for heavy parts, such as a flywheel or balance weight for model engines.
Brass is prized for the highly polished finish it can produce however, since brass surface will oxidise when exposed to the elements, it it preferable to apply a clear lacquer protective coating.
Brass is very expensive when compared to other materials so
Fig.4, Brass (JIS C2800)
it is used very selectively.
Material Identification
Usually, a billet (column) of material is sold in unit lengths of 1 to 2 meters (or more). These billets typically carry the material identification written on the end of the billet as seen in the photos on the right. As the billet is usually cut to provide the work piece, take care to cut from the end opposite the markings so as to leave the markings for subsequent identification. Fig.5, Material Indication
Common Shapes
Material is usually supplied as common shapes and these are (a) Billets (columns), (b) flat bar (boards), (c) Angle (L-shaped), (d) "C" channel (C-shaped) and (e) pipe. The correct selection of material assists in simplifying a project.
Fig.6, Common Material Shapes
Common machining sizes of billets
Common billet sizes are: 30mm, 40mm, 50mm, 60mm and 80mm (However many other sizes can be ordered). As the surface finish of many billets is not satisfactory for a finished project, they often have to be machined to suit the project. Should you want a finished diameter of the above mentioned sizes, then it is necessary to commence with the next larger size in the range and machine this down to the desired diameter. The exception to this can be stainless steel with diameters of 10mm or less as the surface finish of these is quite high and sometimes suitable for the job in hand.
Chapter 1. Basic Machining and Tips
Removal of Burrs
Removing of Burrs
The burrs are rough edges which are generated as a result of the cutting process. It is often called a flash in English. There are the visible burrs as shown in Figure 1 and the invisible burrs, which are confirmed by touching the edge. In order to make an accurate part, it is very important to remove the burrs with a file. We must remove them carefully after the cutting process.
Fig. 1, Visible Burrs
Why we need to remove burrs?
(1) In most cases of the machining process, the material is set to a chuck of a lathe or a vice of a milling machine as shown in Figure 2. If the burrs are remained, the material can not be accurately set. And as a consequence, the piece will be mounted at an askew or off center as shown in Figure 3. Also, small amounts of waste can become trapped and as a result can also cause askew or off center work pieces.
Fig. 2, Setting a Material
Fig. 3, If There is a Burr...
(2) If the burrs are not removed, the size of the part can not be accurately measured. It is therefore imperative to remove the burrs before the measurements are taken.
(3) Another reason for removing burrs is that the can cause injury to personal due to sharp edges.
(4) Also if burrs are not removed, they can seriously affect the assembly process of the parts.
Fig. 4, If a Burr is Remained...
Removiing a Burr using File and a Wooden Surface
It is advisable to use a wooden work surface to aid in the removal of a burr as the timber surface provides a good support while at the same time it does not damage the file if it comes into contact with the timber. Not that the file is "Pushed" along the edge and not "Pulled".
Fig. 5, Using a board to Facilitate the Removal
of a Burr
Lathe Process and Removal of a Burr
A burr can also be generated during the lathe process. It can be easy removed by applying a file to the burr on the rotating material. Be careful to not touch the rotating part with your finger.
Fig. 6, Removal of a Burr after Lathe
Process
Remove a Burr after Drilling Process
A burr generated during a drilling or tapping process is removed using a bigger drill. A little burr can be easily removed by rotating the drill bit by hand. Larger burrs may need to be removed by mounting the drill bit in a drilling machine.
Fig. 7, Removing a Burr by Hand after Drilling
Measurements
How to Use Vernier Callipers
In the machining process, we use vernier callipers or a micrometer for taking measurements. General analog vernier callipers as shown in Figure 1 can measure with the minimum unit of 1/20 mm. Several types of digital vernier callipers as shown in Figure 2 can measure with the minimum unit of 1/100 mm.
Fig. 1, Analog Vernier Callipers Fig. 2, Digital Vernier Callipers Examples
The vernier callipers can measure a side length, an outer and inner diameter, and a depth as shown in Figures 3 to 6.
Fig. 3, Measurement of an Outer Diameter Fig. 4, Measurement of a Side Length
Fig. 5, Measurement of an Inner Diameter Fig. 6, Measurement of a Depth
Keep a perpendicular position in measuring!
The vernier callipers must be kept the perpendicular position in measuring. Typically, when a beginner measures the size of a complex shaped part, the result can be inaccurate as the measuring device is often not maintained parallel to measured piece.
How to Use a Micrometer
When close tolerances are required, measurements are taken with a micrometer due to its superior accuracy over a vernier calliper. The micrometer as shown in Figure 7 can measure with the minimum unit of 1/1000 mm.
Fig. 7, Micrometer Fig. 8, Measurement with a Micrometer
Which do you use the vernier callipers or the micrometer?
The "For & Against" of using micrometers and vernier callipers are:
Vernier Calliper:For: A large range of measurements can be made using the one measuring device.Against: The majority of vernier callipers do not provide sufficient accuracy for close tolerance measurements.
Micrometer:For: The micrometer provides a greater degree of accuracy for close tolerance work.Against: Due to the limited size range for a given micrometer, it is necessary to have a number of micrometers to cater for the full range of measurements you may encounter.
Dimensional Tolerance
Necessity of Dimensional Tolerance
It is almost impossible (and sometimes uneconomical) to maintain the strict degree of accuracy as listed on a plan. To accommodate this, it is normal to display measurements with a plus or minus (+/-) tolerance which allows for some margin of error. Care needs to be taken however when determining such +/- tolerance, particularly where there are mating parts. For example, a shaft which is machined to its maximum tolerance may not fit a gear center that has been machined to it minimum tolerance or an unsatisfactory loose fit would result from the shaft being machined to its minimum tolerance with the gear center machined to its maximum tolerance.
Usually, the dimensional tolerance is decided at the design stage and a Machinist must take care to apply the required dimensional tolerance and to ensure that discrepancies are not introduced as a result of poor workmanship of measuring techniques.
Dimensional Tolerance of a Shaft and a Hole
Figure 1 shows the plans of a fish robot's joint. In the plan, a shaft is inserted in the holes of Parts 1 and 2. The diameter of the holes are required to be on the plus-side of the dimensional deviation, and the diameter of the
shaft is required minus-side of the dimensional deviation. Part 2 is inserted a slot of Part 1. Then the slot of Part 1 must have a plus-side dimensional deviation, and the size of Part 2 must have a minus-side dimensional deviation.
Additionally, holes of many "commercially available" mechanical parts, such as gears and couplings, are already finished to plus-side dimensional deviations.
Dimensional Tolerance of a Reamer
When an accurate hole is required, we often use the hand tool called 'a reamer'. A diameter of a general reamer has plus-side dimensional deviation. Therefore, when a hole is made by a reamer that has 12 mm of nominal diameter, the hole is finished plus-side dimensional deviation than 12 mm.
Fig. 1, Dimensional Tolerance of a Shaft and Holes
Installation of a Bearing
Many machines have bearings that support a rotating shaft. Various standardized bearings are commercially available and easily obtained. Generally, the outer diameter of a bearing has a minus-side dimensional deviation. The hole for the bearing must be finished to a plus-side dimensional deviation. On the other hand, the inner diameter of a bearing is a plus-side dimensional deviation, then the shaft to be inserted into the bearing must be finished to the minus-side dimensional deviation.
Fig. 2, Installation of a Bearing
A Slot for an O-ring
An O-ring is a mechanical component which is used as a seal device for various fluids. In order that it should work correctly, a slot of the O-ring must be finished to required dimensional tolerance. The values of the required dimensional tolerance are shown in typical O-ring catalogues.
Fig. 3, A Slot for an O-ring
Installation of an One-way Clutch
In some special cases, as exampled below, a minus sided dimensional deviation is required:
Figure 4 shows a one-way clutch fitted with bearings and a shaft. In order to obtain the correct operation, the outer ring of the one-way clutch must mate firmly with it mating hole. To achieve this, the hole needs to be finished on the minus-side of the dimensional deviation.
In this case, the hole was finished with a hand reamer of 11.98 mm diameter, though the nominal dimension of the one-way clutch is 12 mm. Fig. 4, Installation of an One-way Clutch
Which is the Dimensional Deviation Plus- or Minus-side?
Much care and consideration needs to be given to this issue and the results of the determination needs to be clearly stated on the plans.
Surface Finish
In the case of general machining, we do not measure the surface finish in the machning process. However, when we consider the order of the machining process, it is very important that we know the required surface finish.
For example, the seal surface for an O-ring must have a high degree of accuracy of the surface finish as shown in Figure 5(a). If it has a rough surface, the O-rings are damaged during the assembly stage. Also the sliding surface as shown in Figure 5(b) must have high accurate surface finish.
In order to obtain a high surface finish with a lathe or a milling process, a slow movement of a tool and high blade speed gives better results.
Fig. 5, Examples of a Flat Surface
The Standard Surface
As described above, we cannot always finish the actual size to the same as that stated in a plan. In order to achieve the required degree of accuracy, we need to determine a "standard reference point" and plan the measurements from this point for an example of mating parts. In the case of mating parts (see Figure 6), these are where the parts mate is often used as the reference point as this provides a common reference point on both parts (see figure 7).
Care needs to be taken when planning reference points as any errors can be accumulative resulting in parts not fitting together. The reference point varies from job to job as the complexity of shapes provide many challenges to accurate measuring and setting-out.
Then it is important to decide the standard surface for measuring of the length or the machiningof the location. If the decided standard surface is not suitable, errors are piled up, and the completed parts often cannot be constructed as the completed machine. First, see the part plan carefully, and consider where is decided the standard surface.
The deciding of the standard surface of a part is different by the shape or how-to-use. When several boards are constructed, the surface touched other parts is very often decided as the standard surface (see Figure 6). When the we make holes in a circumference, the center of circle is very often decided the standard point (see Figure 7).
Fig. 6, Holes Inserted a Shaft Fig. 7, Holes of a FlangeMarking-off
Marking-off Tools
Marking-off is the process of drawing lines on the raw stock corresponding to the dimensions on the plan. Figures 1 to 6 show the tools used for the marking off.
Determining the Need for Accuracy
In the case of preliminary cutting or "roughing-out" it is satisfactory to mark-up using generally accurate measurements however, when finishing or high precision is needed, then it is essential that utmost care be taken to mark-up the work piece with extreme care and attention to detail.
When working in a commercial environment, there needs to be a balance between achieving the desired quality of workmanship with that of the time taken to complete the work.
Fig. 1, Marking-off ScribeA marking-off scribe is used for drawing lines on material. Its point is sharp, and is tempered to ensure that point is maintained.
Fig. 2, Steel RuleThe steel rule is used for measuring-out and drawing lines. A good quality steel rule is a good investment in achieving accuracy.
Fig. 3, Steel CompasA compas is used for drawing circles or an arc. Its points are also sharp and hardened.
Fig. 4, Center Punch and HammerA center punch is used for marking an "indent" before a hole is bored with a drilling machine. The point is usually set to the point of intersection between two marking line.
Fig. 5, Block and Flat TableGenerally, the marking process is done on a flat table, called a marking-off table. The block with a V-shaped slot, as shown in the above photograph useful when marking our round or irregular objects.
Fig. 6, Height GaugeThe height gauge as shown in the above photograph can measure with the accuracy of 1/100 mm. The point of the gauge is also a marking scribe, so that it can be used for drawing accurate lines by sliding the gauge on the flat table while at the same time scribing along the work piece.
Marking-off and Drilling
The procedure of making holes in a simple mechanical process and is presented as follows.
(1) Drawing of the Horizontal Center LinesTouch the material to the block, and slide the hight gauge.
(2) Drawing of the Vertical Center LinesRotate the material to 90 degrees. And draw the vertical lines.
(3) Set the PointAfter marking the center point with the center punch, set the drill.
(4) DrillingDrill a hole with the drilling machine.
(5) DrillingIt may be necessary to withdraw the drill from the work piece to remove any swarf that may otherwise clog the drill bit
(6) CompletionWhen drilling is completed it is usually necessary to remove any burrs as previously discussed.
Fig. 7, Flow of Markings and Drillings
Drilling
How to Use a Drill
A drill is one of the most useful and most often used tools. Generally, a drill bit that is used metal work, has two edges with angles of 90 or 120 degrees.
Various drill bits, that have from less than 1 mm diameter to more than 40 mm diameter, are available. However, the chuck of the general drilling machines can use only shaft sizes of less than 13 mm diameter. However, for larger drills and milling machines, drill bits are designed with a "Morse" taper as shown in figure 2.
Fig.1, Drills Fig.2, Taper Drill
Machines for Milling and Drilling
Figures 3 to 5 respectively pictures a drilling machine, a milling machine and a hand drill. Hand drills are only advised when a high degree of accuracy is not required or it is not practical to mount the work piece in the drilling machine.
Fig.3, Drilling Machine
Fig.4, Milling Machine Fig.5, Hand Drilling Machine
Wheting of Drill
To achieve accuracy of drilling, the drill bit must be sharp. The bigger drills, such as 6 mm diameter plus, can be wheted (sharpened) using a bench grinder. However, it can be a very difficult process and much practice is needed for the beginner.
Fundamentally, in the wheting process, two edges of the drill have to touch the grinding medium at the same time.
The first step in the whetting proves is to grind the two sides of the drill to an equal angle as shown in figure 7(a). Note, if the angle of both each side is not even as in figures 7 (b) and (c), the drill will not provide a satisfactory cut.
The second step involves grinding to make an "angle of relief" as shown in figure 8(a). Note that if a drill bit does not have an angle of relief, than it is not possible for the drill to drill a hole in the work piece. An example of incorrect angles of relief can be seen in figures 8 (b) and (c).
Fig.6, Edges of a Drill
Fig.7, Angles of Edges Fig.8, Angle of ReliefMarking-off and Drilling a Cylinder
Drillings of Circular Holes
In any mechanical parts, we often drill holes on a circular pattern on the face of a cylindrical as shown in Figure 1.
Figures 2 to 7 shows the procedure of a marking-off and drilling on a typical part.
Fig.1, Part Drawing
Fig.2, Marking the Center Lines on the Work PieceThe work piece is set on a square block and securely fastened in the "vee" section. Find the center of the work piece and scribe a vertical a line across the face. Care must be taken to find the exact center otherwise the desired accuracy cannot be obtained.
Fig.3, Markings of Center Lines (continued)Turn the square block 90 degrees and mark the line across the face as it step one to achieve the intersecting line.
Fig.4, Marking with a Center PunchFind the center of each line at the exact location to be drilled and using a center punch and hammer, lightly mark the drilling position. Check the dimensions and if they are correct, re-punch the marks but this time using a bit more force.
Fig.5, Marked-off MaterialThe marking-off process is complete and the work piece is ready to be drilled.
Fig.6, Processing of a Drilling MachineSecure the work piece in the drilling machine vice and drill the holes.
Fig.7, Completed PartThe finished piece.
Using V-shaped Block
A V-shaped block as shown in Figures 8 and 9 is used for the marking-off of a cylindrical part. Note, the vee block shown does not have a securing clamp so it is not as convenient to use as one with a clamp.
Fig.8, V-shaped Block Fig.9, Setting of a part on the Block
Chapter 1. Basic Machining and Tips
Making a Screw Thread
Elementary Knowledge of Screws
Machine screws are extensively used for securing parts. The number of different types and sizes of machine screws, nuts & bolts prohibit the possibility of introducing them all here so the following information addressed the elementary information only.
Types of Threads
Almost of the thread have triangle shaped threads. On the other hand, square shaped and trapezoid shaped thereads are used moving machinery which need high accuracy, such as a lathe.
In respect to thread standards, there are a metric thread (M), a parallel thread for piping (PF), a taper thread for piping (PT), and an unified thread (UNC, UNF). The following information is related metric threads, because they are the most widely used in Japan and many countries around the world.
Terms used for Threads
Figure 1 shown an image of a thread. One of the most important terms used is that of the outer diameter. In the case of a metric thread, the bolt is named in accordance with its outer diameter e.g a bolt with a 5 mm outer diameter is known as an M5 bolt.
The "Pitch" of the tread is another important feature of a thread. The pitch is defined as the interval (distance) between adjoining threads. e.g. Nuts & bolts must have the same pitch as well as diameter if they are going to be used together.
The principles of cutting threads in nuts and bolts is that the bolt (male thread) is usually cut from a rod of material which has the same diameter has the intended finished bolt. The nut is made from a larger stock witch has a hole drilled through it that is slightly larger than that of the rod diameter. A thread of the same pitch is then cut which results in two mating threads. The same principles apply for cutting holes in places and other work pieces. (such an in the cylinder discussed earlier.)
Fig.1, Terms of Screw
Fig.2, Imagine of Thread Cutting Processing
Screw and Clearance Hole
Screws are typically used for securing mating parts. When two pieces are joined together using screws, one piece is made with threads, and another piece is made with clearance holes, which have bigger diameters than that of the screws. If the diameter of the clearance hole is too small, the piece cannot be assembled as the screw will not fit through the hole. Also, if the diameter of the clearance hole is too big, , the piece will be loose as the hole will provide a sloppy fit. Therefore, we must provide make suitable diameter clearace holes. As a "rule of thumb", the diameter of the clearance hole has more 10 % than the diameter of the screw. For examples, the clearance hole for a M3 screw has 3.2 mm or 3.5 mm diameter. the clearance hole for a M4 screw has 4.2 mm or 4.5 of diameter. And we would make a hole with 5.5 mm of diameter for a M5 screw.
Fig.3, Screw and Clearance Hole
Thread Making Process
When we make the male thread, generally we use a die tool. When we make the female thread, we use a tap tool. If we do not have the suitable tools, we can also make the thread using a lathe as described in Chapter 3.
Caution
When we make the threads using the tap or the die, care should be taken in respect for the following.(1) Start the thread with a perpendicular positioning of the tap or the die.(2) Turn the tap or die in quarter turns and "back off" quarter
Fig.4, Tap and Die
turns to remove melat chips so that they don't clog the tool. (3) Always use a cutting oil.
Tread Cutting using a Hand Tap
Figure 5 shows taps which are used to make female threads. They are usually used with a tap handle as shown in Figure 6. In respect to the tread cutting process, we first, we make a hole with suitable diameter and suitable depth (see Table 1). Next, we start to turn the tap in a clockwise direction.
There are typically three types of taps used as seen in figure 5. Of the three tap types there is a tapered tap to facilitate the initial thread cutting, an intermediate type that is used to progress the thread after it has been started and then finally, a "Bottoming" thread which is used to obtain the full thread depth when cutting a thread that does not go the whole of the way trough the piece.
Taps can be easily broken and if the tap is broken in the work piece, it can be almost impossible to remove. It is therefore, very prudent to take care to ensure that metal chips do not build-up in the tap and also that the tap does not overheat as a result of the cutting process through the use of a cutting lubricant.
Fig.5, Taps
Fig.6, A Tap with a Tap handle Fig.7, Teread Cutting using a Tap
Recommended Tap Hole Size
Table 1 lists diameters of hole sizes for metric female threads and piping threads (PT, PF). Please note that the diameter of the hole equals the approximate difference of the diameter of the thread and the thread pitch. It may be necessary the allow a grater hole clearance if for example we were making a thread in hard stainless steel.
Table 1, Recommended Tap Hole Size
Cutting using a Hand Die
Figure 8 shows a die and a die handle which are used to make male threads. The procedure of the threading is the same of the taps. But it is more difficult to start the thread cutting process than with tapping as dies do not have an equivalent to a tapered starting tap with perpendicular than the tapping.
The thread cutting process using a die usually typically results in a smaller diameter of the original piece so care needs to be taken in selecting the correct size stock. If the stock is too small, this will result in a shallow thread depth resulting in an unsatisfactory thread. The die also created a bevel on the thread which is necessary for a close fit.
If you have a lathe, the job of cutting a thread can be easier as it is possible to use the "STOPPED" lathe to assist in starting the thread as shown in figure 9. The die is pushed by the drill chuck aligned perpendicularly to the piece and after. After enough thread is cut, the drill chuck is removed and the die handle is then turned by hand.
Fig.8, A Die and A Die Handle
Fig.9, Thread Making using Die
More on Threads
How does the screw make perpendicularly?
If the thread needs to be held perpendicular to the piece, then it is important that the thread incorporate a shoulder to act as a "load bearing surface" as depicted in figure 10.The threaded section does not have the mechanical properties necessary to remain perpendicular without such a shoulder.
Fig.10, How to Make Perpendicular Screw
Chapter 1. Basic Machining and Tips
Grinders
A Useful Tool for Machining: Bench Grinder
A bench grinder is a tool which rotates a grindstone at high speed. It is used for grinding off burrs or tools, such as a byte of a lathe and a drill. It is one of the machines which is indispensable to the machining process.
Fig.1, Bench Grinder CAUTIONS!
The bench grinder is a very dangerous machine, though it is simple. Please note the following Safety Advice.
(1) In the grinding process, the fingers are
sometimes near the rotating grindstone so take care not to come into contact with the grindstone. The material being ground can become hot to the touch and it is advisable to cool the part in a coolant solution, particularly if removing large amounts of material. Resist the urge to use gloves as gloves can easily be caught by the rotating grindstone resulting in server injury.
(2) When grinding small parts, extra care must be taken as such parts can be "grabbed" by the grins stone and projected out of the grinder at high speeds resulting in severe injury being sustained ALWAYS USE EYE PROTECTION WHEN GRINDING.
(3) Generally, the bench grinder is used for grinding steel however, if grinding aluminium, copper or other alloys, the grindstone can become blocked and this leads to inefficient grinding and overheating.
(4) You should periodically inspect the grindstone for cracks or chips and re-dress the stone or replace as required. ENSURE YOU REMOVE THE PLUG FROM THE SOCKET BEFORE THE INSPECTION TO PREVENT ACCIDENTAL STARTING.
Convenience Tool: Hand Grinder
A hand grinder as shown in Figure 2 is also a tool which rotates a grindstone but in this case the grinding medium is a thin disc that can be used for either grinding or cutting metal. It is usually used for cutting off material after a welding process or cutting off burrs. Although it is a convenient tool, it is a dangerous tool like the bench grinder. Again, eye protection should be worn when using a hand grinder.
Fig.2, Hand Grinder Fig.3, Use of the Hand Grinder
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Pengecoran adalah suatu proses manufaktur yang menggunakan logam cair dan cetakan untuk menghasilkan parts dengan bentuk yang
mendekati bentuk geometri akhir produk jadi. Logam cair akan dituangkan atau ditekan ke dalam cetakan yang memiliki rongga sesuai
dengan bentuk yang diinginkan. Setelah logam cair memenuhi rongga dan kembali ke bentuk padat, selanjutnya cetakan disingkirkan dan
hasil cor dapat digunakan untuk proses sekunder. Pasir hijau untuk pengecoran digunakan sekitar 75 percent dari 23 million tons coran yang
diproduksi dalam USA setiap tahunnya.
Untuk menghasilkan tuangan yang berkualitas maka diperlukan pola yang berkualitas tinggi, baik dari segi konstruksi, dimensi, material pola,
dan kelengkapan lainnya. Pola digunakan untuk memproduksi cetakan. Pada umumnya, dalam proses pembuatan cetakan, pasir cetak
diletakkan di sekitar pola yang dibatasi rangka cetak kemudian pasir dipadatkan dengan cara ditumbuk sampai kepadatan tertentu. Pada lain
kasus terdapat pula cetakan yang mengeras/menjadi padat sendiri karena reaksi kimia dari perekat pasir tersebut. Pada umumnya cetakan
dibagi menjadi dua bagian yaitu bagian atas dan bagian bawah sehingga setelah pembuatan cetakan selesai pola akan dapat dicabut
dengan mudah dari cetakan.
Inti dibuat secara terpisah dari cetakan, dalam kasus ini inti dibuat dari pasir kuarsa yang dicampur dengan Airkaca (Water Glass / Natrium
Silikat), dari campuran pasir tersebut dimasukan kedalam kotak inti, kemudian direaksikan dengan gas CO2 sehingga menjadi padat dan
keras. Inti diseting pada cetakan. Kemudian cetakan diasembling dan diklem.
Sembari cetakan dibuat dan diasembling, bahan-bahan logam seperti ingot, scrap, dan bahan paduan, dilebur di bagian peleburan. Setelah
logam cair dan homogen maka logam cair tersebut dituang ke dalam cetakan. Setelah itu ditunggu hingga cairan logam tersebut membeku
karena proses pendinginan. Setelah cairan membeku, cetakan dibongkar. Pasir cetak, inti, dan benda tuang dipisahkan. Pasir cetak bekas
masuk ke instalasi daur ulang, inti bekas dibuang, dan benda tuang diberikan ke bagian fethling untuk dibersihkan dari kotoran dan dilakukan
pemotongan terhadap sistem saluran pada benda tersebut. Setelah fethling selesai apabila benda perlu perlakuan panas maka diproses di
bagian perlakuan panas.
Proses pengecoran sendiri dibedakan menjadi dua macam, yaitu traditional casting dan non-traditional/contemporary casting.
Teknik traditional terdiri atas :
1. Sand-Mold Casting
2. Dry-Sand Casting
3. Shell-Mold Casting
4. Full-Mold Casting
5. Cement-Mold Casting
6. Vacuum-Mold Casting
Sedangkan teknik non-traditional terbagi atas :
1. High-Pressure Die Casting
2. Permanent-Mold Casting
3. Centrifugal Casting
4. Plaster-Mold Casting
5. Investment Casting
6. Solid-Ceramic Casting
Perbedaan secara mendasar di antara keduanya adalah bahwa contemporary casting tidak bergantung pada pasir dalam pembuatan
cetakannya. Perbedaan lainnya adalah bahwa contemporary casting biasanya digunakan untuk menghasilkan produk dengan geometri yang
kecil relatif dibandingkan bila menggunakan traditional casting. Hasil coran non-traditional casting juga tidak memerlukan proses tambahan
untuk penyelesaian permukaan.
Jenis logam yang kebanyakan digunakan di dalam proses pengecoran adalah logam besi bersama-sama dengan aluminium, kuningan,
perak, dan beberapa material non logam lainnya.
Dasar Teknik Pembentukan dan Pengecoran Logam
Dasar Teknik Pembentukan
Teknik pembentukan logam merupakan proses yang dilakukan dengan cara memberikan perubahan bentuk pada benda kerja.
Perubahan bentuk ini dapat dilakukan dengan cara memberikan gaya luar sehingga terjadi deformasi plastis. Aplikasi pembentukan
logam ini dapat dilihat pada beberapa contohnya seperti pengerolan (rolling), pembengkokan (bending), tempa (forging), ekstrusi
(extruding), penarikan kawat (wire drawing), penarikan dalam (deep drawing), dan lain-lain.
Tahapan yang dilakukan dalam proses pembentukan untuk suatu konstruksi ini meliputi:
1. Mendesain alat sesuai dengan fungsi dan kegunaannya.
2. Menganalisa konstruksi pelat terhadap dan pembebanan
3. membuat gambar desain
4. Menentukan jenis bahan pelat
5. Menentukan metode penyambungan dan penguatan
6. Menentukan metode perakitan
7. Membuat gambar kerja konstruksi alat
8. Membuat gambar bentangan
9. Melakukan pemotongan awal (pre cutting)
10. Melakukan pemotongan bahan pelat
11. Melakukan proses pembentukan
12. Menentukan alat bantu atau model
13.Metode perakitan
14. Pengukuran dimensi konstruksi
15. Uji coba konstruksi
16. Finishing
Teknologi pembentukan dewasa ini banyak digunakan untuk berbagai keperluan. Konstruksi ini biasanya dibedakan berdasarkan
dimensi pembentukan yang diinginkan.
Dasar Pengecoran Logam
Proses Pengecoran (casting) adalah salah satu teknik pembuatan produk dimana logam dicairkan dalam tungku peleburan kemudian
di tuangkan kedalam rongga cetakan yang serupa dengan bentuk asli dari produk cor yang akan dibuat. Pengecoran juga dapat
diartikan sebagai suatu proses manufaktur yang menggunakan logam cair dan cetakan untuk menghasilkan bagian-bagian dengan
bentuk yang mendekati bentuk geometri akhir produk jadi. Proses pengecoran sendiri dibedakan menjadi dua macam, yaitu traditional
casting (tradisional) dan non-traditional (nontradisional).
Teknik tradisional terdiri atas:
1. Sand-Mold Casting
2. Dry-Sand Casting
3. Shell-Mold Casting
4. Full-Mold Casting
5. Cement-Mold Casting
6. Vacuum-Mold Casting
Sedangkan teknik non-traditional terbagi atas :
1. High-Pressure Die Casting
2. Permanent-Mold Casting
3. Centrifugal Casting
4. Plaster-Mold Casting
5. Investment Casting
6. Solid-Ceramic Casting
Ada 4 faktor yang berpengaruh atau merupakan ciri dari proses pengecoran, yaitu:
1. Adanya aliran logam cair kedalam rongga cetak
2. Terjadi perpindahan panas selama pembekuan dan pendinginan dari logam dalam cetakan
3. Pengaruh material cetakan
4. Pembekuan logam dari kondisi cair
Klasifikasi pengecoran berdasarkan umur dari cetakan, ada pengecoran dengan sekali pakai (expendable mold) dan ada pengecoran
dengan cetakan permanent (permanent mold). Cetakan pasir termasuk dalam expendable mold. Oleh karena hanya bisa digunakan
satu kali pengecoran saja, setelah itu cetakan tersebut dirusak saat pengambilan benda coran. Dalam pembuatan cetakan, jenis-jenis
pasir yang digunakan adalah pasir silika, pasir zircon atau pasir hijau. Sedangkan perekat antar butir-butir pasir dapat digunakan,
bentonit, resin, furan atau air gelas.
Secara umum cetakan harus memiliki bagian-bagian utama sebagai berikut :
o Cavity (rongga cetakan), merupakan ruangan tempat logam cair yang dituangkan kedalam cetakan. Bentuk rongga ini sama
dengan benda kerja yang akan dicor. Rongga cetakan dibuat dengan menggunakan pola.
o Core (inti), fungsinya adalah membuat rongga pada benda coran. Inti dibuat terpisah dengan cetakan dan dirakit pada saat cetakan
akan digunakan.
o Gating sistem (sistem saluran masuk), merupakan saluran masuk kerongga cetakan dari saluran turun.
o Sprue (Saluran turun), merupakan saluran masuk dari luar dengan posisi vertikal. Saluran ini juga dapat lebih dari satu, tergantung
kecepatan penuangan yang diinginkan.
o Pouring basin, merupakan lekukan pada cetakan yang fungsi utamanya adalah untuk mengurangi kecepatan logam cair masuk
langsung dari ladle ke sprue. Kecepatan aliran logam yang tinggi dapat terjadi erosi pada sprue dan terbawanya kotoran-kotoran
logam cair yang berasal dari tungku kerongga cetakan.
o Raiser (penambah), merupakan cadangan logam cair yang berguna dalam mengisi kembali rongga cetakan bila terjadi penyusutan
akibat solidifikasi.
Logam-logam yang dapat digunakan untuk melakukan proses pengecoran yaitu: Besi cor, besi cor putih, besi cor kelabu, besi cor
maliable, besi cor nodular, baja cor dan lain-lain. Peleburan logam merupakan aspek terpenting dalam operasi-operasi pengecoran
karena berpengaruh langsung pada kualitas produk cor. Pada proses peleburan, mula-mula muatan yang terdiri dari logam, unsur-
unsur paduan dan material lainnya seperti fluks dan unsur pembentuk terak dimasukkan kedalam tungku.
Fluks adalah senyawa inorganic yang dapat “membersihkan” logam cair dengan menghilangkan gas-gas yang ikut terlarut dan juga
unsur-unsur pengotor (impurities) Fluks memiliki beberpa kegunaan yang tergantung pada logam yang dicairkan, seperti pada paduan
alumunium terdapat cover fluxes (yang menghalangi oksidasi dipermukaan alumunium cair),. Cleaning fluxes, drossing fluxes, refining
fluxes, dan wall cleaningfluxes. Tungku-tungku peleburan yang biasa digunakan dalam industri pengecoran logam adalah tungku
busur listrik, tungku induksi, tungku krusibel, dan tungku kupola.
Moulding ProductionMoulding Production adalah proses pencetakan pola atau patern yang sudah disiapkan pada tempat atau lahan yang sudah memenuhi standar pengecoran.
Moulding Setting
Moulding Setting adalah proses penyempurnaan pola atau cetakan yang telah dibuat dalam proses moulding agar menghasilkan cetakan produk yang sesuai.
DisassemblingProses ini adalah pembongkaran hasil casting yang sudah dituang dengan cairan material hasil melting. Dilakukan pemisahan hasil casting berdasarkan komposisi cairan kemudian membersihkan sisa pasir dari moulding yang masih melekat pada hasil cetakan.
Finishing
Setelah barang yang sudah dipisahkan dari pasir lalu siap digurinda/dipotongmenggunakan cutting wheel atau bunner. Dan penyempurnaan visual barang denganmenggunakan alat short blast.
Melting Melting adalah proses peleburan logam atau pembuatan cairan material berdasarkan komposisi bahan yang akan dituang dalam cetakan
Sebelum proses berikutnya dilakukan evaluasi (Quality Control) material yang dihasilkan dalam proses Melting untuk menjamin kualitas hasil melting sebelum dituang dan dicetak. Proses evaluasi dan pengendalian kualitas hasil melting menggunakan perlatan sebagai berikut :
Spektro Meter
Hardness Tester
Termometer Digital
