Metal Processes Flashcards

Manufacturing with metals covers a broad range of processes. You should become familiar with the main types of processing and be able to provide examples of where they are used in the manufacture of products.

1
Q

There are three areas of processing metals. What are they?

A

The three areas of processing metals are:

  1. Wasting - where material is cut away
  2. Addition / joining - where materials are joined together
  3. Redistribution - where materials are reshaped without loss of material
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2
Q

List 8 metal wasting processes.

A

Metal Wasting Processes:

  1. Sawing/cutting
  2. Filing
  3. Drilling
  4. Milling
  5. Grinding
  6. Sanding
  7. Blanking
  8. Piercing
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3
Q

List the 3 main types of metal joining processes.

A

Metal Addition / Joining processes

  1. Mechanical fixings - eg. bolts, screws and rivets
  2. Permanent fixing - eg. welding, brazing and soldering
  3. Adhesives eg. specialist glues
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4
Q

List the 4 main areas of metal redistribution processes.

A

Metal Redistribution Processes:

  1. Casting - eg. sand and die casting
  2. Forging - eg. hot and cold forging
  3. Forming - eg. press forming, embossing and coining
  4. Sintering
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5
Q

What is the name of this process and what type of process is it?

A

Plasma cutting

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6
Q

What are the 3 advantages of plasma cutting sheet metals?

A

The advantages of plasma cutting are:

  1. Very little waste material is produced
  2. The cut is very fine
  3. Little or no finishing is required to remove burrs
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7
Q

What does the term finishing mean?

A

Finishing means the removal of burrs or other blemishes in a material following processes.

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8
Q

Sheet metals can be cut using a guillotine into useable sizes. This is done using a shearing action similar to the way scissors cut through paper. Draw a diagram showing how the shearing action works.

A

Shearing Action

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9
Q

Draw a diagram that shows blanking and piercing sheet metal.

A

Blanking and piercing sheet metal. Click hereto watch a video on how coins are made.

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10
Q

Is the disc shaped sheet material, used to make soft drinks cans, a blank or a sheet that has been pierced?

A

Soft drinks cans are made from disc shaped blanks. Click here to read about how a drinks can is made.

Click hereto watch a video about how aluminium cans are made.

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11
Q

Name a product or component that requires both blanking and piercing.

A

A casing for a desktop computer requires both blanking and piercing. The net of the case is blanked and the ventilation holes are pierced.

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12
Q

Heavyweight products such as tanks and diggers use steel sheets that can be between 8 to 12mm thick. What simple type of cutting process could be used on this?

A

The profile cut be cut with an oxy-acetylene torch.

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13
Q

What cutting process produces a finer cut than plasma cutting?

A

Laser cutting produces profiles with a width of cut that is far narrower than plasma, resulting in less waste material.

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14
Q

Draw a cross section of a laser cutter nozzle.

A
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15
Q

Both plasma and laser cutting can be automated by using CNC machines. What does CNC stand for?

A

Computer Numerical Control - CNC machines use a special machine programming language which can be generated from CAD drawings.

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16
Q

Apart from a finer cutting width, what other advantages does laser cutting have over plasma?

A
  1. A far broader range of materials (MDF, plywood, acrylic, paper etc) can be laser cut because plasma relies on the electrical conductive properties of metals.
  2. Laser cutting can also be used for engraving by altering the power and speed settings.
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17
Q

What does the term welding mean?

A

Welding is a general term given to joining metals and some polymers, by heat fusing the component materials together.

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18
Q

What is oxyacetylene gas welding used for?

A

Oxyacetylene gas welding is used for the prefabrication of sheet steel, tubes and plates.

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19
Q

What type of process is press-forming?

A

Press-forming is a redistribution process.

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20
Q

Press-forming is carried out at room temperature. However the material needs to be ductile. How can a material’s ductility be increased?

A

Some metals need to be annealed to be ductile enough for press-forming.

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21
Q

What two tools are used in the press-forming process?

A

Press-forming is carried out using a die and punch, both made from toughened die steel.

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22
Q

Draw a diagram of the press forming process.

A

Press-forming

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23
Q

How is press-forming used in the automotive (car) industry?

A

Press-forming is used to create car body panels. Click here to see how a car door panel is made.

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24
Q

What are the advantages of press-forming sheet metals?

A
  1. Creating a more 3D shape using press-forming increases the stiffness of the sheet metal.
  2. Less material is required as the sheet becomes more rigid.
  3. Holes can be cut at the same time as press-forming.
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25
Q

What other everyday objects are press-formed from sheet metals?

A
  1. Radiator panels
  2. Meat trays
  3. Cooker tops
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26
Q

Cupping is used to create cans from disc shaped blanks. Draw the 3 stages of the cupping process.

A

Cupping

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27
Q

Embossing is a press-forming process used to create decorative panels. List 3 products that are embossed.

A

Embossed products include:

  1. Jewellery
  2. Biscuit tin lids
  3. Paper & Card products such as letter headed paper and greetings cards
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28
Q

After cupping a disc shaped blank, an aluminium can is then deep drawn. Draw a diagram of the deep drawing process.

A

Deep drawing

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29
Q

How much can the thickness of the wall of a can be reduced by during the deep drawing process?

A

It is possible to reduce the thickness of the wall to a third of its original size using deep drawing.

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30
Q

Name a traditional process that forms circular sheet metals into 3D hollow objects.

A

Spinning

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31
Q

Spinning is done on a machine similar to a lathe. Draw a diagram to show how the process is done.

A

Spinning

32
Q

Name 3 products that are made using the spinning process.

A

Spinning is used to create

  1. Woks
  2. Saucepans
  3. Desk lampshades
33
Q

On a component made by spinning, what marks would you expect to see?

A

The tell-tale signs of the spinning process are the concentric lines around the outside of the product caused by the path of the tool.

34
Q

Explain how press-forming improves the strength and rigidity of a car body shell.

A

Folding and cupping sheet materials stretches materials thereby work hardening the material as well creating stronger structure.

35
Q

Which area of metal processing does casting belong to?

A

Casting is a redistribution process.

36
Q

When casting, liquid metals are poured into a mould. What materials can moulds be made from?

A

When casting metals, moulds can be made from sand, alloy steels and ceramics.

37
Q

In sand casting, what does the sand contain so that it holds the shape when hot metal is cast into it.

A

Casting sand contains oil that acts as a binder.

38
Q

For sand casting a pattern is required. Draw a pattern and list what it could be made from.

A

A pattern can be made from woods (yellow pine, jelutong), metals (aluminium), polymers (polystyrene).

39
Q

What are the two halves of the sand casting mould called?

A

The drag and the cope.

Click hereto watch a video of the sand casting process.

40
Q

Draw the main stages of the sand casting process.

A

Stages of the sand casting process.

41
Q

In sand casting, what is a runner gate and what is a riser gate?

A

A runner gate is the opening in which the molten metal is poured. A riser gate allows air to escape and is the outlet to the mould. Both are filled with the molten metal and require removal at the end of the process.

42
Q

List three advantages of sand casting.

A
  1. Complex 3D shapes can be produced.
  2. Cores can be used to produce hollow sections.
  3. It’s appropriate for small and longer production runs (automation required).
43
Q

List 3 disadvantages of sand casting.

A
  1. Due to the poor surface finish, some machining will be necessary.
  2. It’s not as accurate as die or investment casting.
  3. It has a relatively low rate of output thereby making it more suitable for small production runs.
44
Q

What are the two main types of die casting?

A

Gravity die casting and Pressure die casting.

45
Q

Which metal alloys are generally used in die casting and why?

A

Zinc, aluminium and magnesium alloys are used as they have low melting temperatures making them suitable for high volume production.

46
Q

Draw and label a gravity die mould.

A
47
Q

Why is the process called gravity die casting?

A

The process uses the force of gravity to ensure that molten metal reaches all parts of the mould.

48
Q

Why are lighted gas jets used to heat the alloy steel mould in gravity die casting?

A

This ensures the even cooling of the cast metal.

49
Q

Why are fluxes used in the gravity die casting process?

A

To prevent the oxidation of the metal as it is being cast.

50
Q

Aluminium and magnesium melt at approximately 650ºc. What temperature does zinc melt at?

A

Zinc melts at 850ºc.

51
Q

What type of products are produced by gravity die casting?

A

Large simple shapes such as car and motorbike wheels.

52
Q

There are two types of pressure die casting. What are they?

A
  1. Hot Chamber High Pressure Die Casting - click here for detailed information
  2. Cold Chamber High Pressure Die Casting - click here for detailed information
53
Q

Draw a diagram explaining the Cold Chamber High Pressure Die Casting process.

A
54
Q

Draw a diagram explaining the Hot Chamber High Pressure Die Casting process.

A
55
Q

How are the dies cooled in hot chamber high pressure die casting?

A

The dies are water cooled so that the product can be pushed out of the die by ejector pins.

56
Q

Which 3 metals (and associated alloys) are suitable for die casting?

A
  1. Aluminium
  2. Magnesium
  3. Zinc
57
Q

Name several aluminium products that are die cast.

A
58
Q

Name several magnesium products that are die cast.

A
59
Q

Name several zinc products that are die cast.

A
60
Q

Which two metals are particularly suitable for multi-slide die casting?

A

Zinc and magnesium are suitable for multi-slide die casting.

61
Q

Draw a simplified diagram of a multi-slide die casting mechanism.

A
62
Q

List 5 advantages of using die casting over sand casting.

A
  1. Finish (surface is as smooth as the die surface)
  2. Accuracy (greater detail is achievable)
  3. Quality of material (rapid cooling effects the material’s structure)
  4. Scale of production (Rapid cooling means as many as hundreds of parts per minute can be produced)
  5. Energy (Low melting point alloys require less heat)
63
Q

Investment Casting is an extremely old process. Explain the process using diagrams.

A
64
Q

List 4 examples of products manufactured using investment casting.

A
  1. Turbine blades for jet engines
  2. Tools and dies
  3. Motorcycle steering head parts
  4. Valves and control parts for the food industry
65
Q

List 5 advantages of the investment casting process.

A
  1. Good finish with a reasonable degree of accuracy
  2. Complicated shapes can be made by other types of casting
  3. Complicated shapes can be made that can not be machined
  4. There is no split line on the final product
  5. It is used where metals/materials have a high melting point
66
Q

List 2 disadvantages of investment casting.

A
  1. The cost is very high.
  2. Size of components is limited by weight
67
Q

What form should a material be for sintering to be used?

A

The metal/material needs to be crushed into a powder.

68
Q

To fuse the powder particles together in the sintering process, what two things have to be applied?

A

Compaction and heat

69
Q

Draw a simple diagram of the sintering process and a diagram of what happens to the powder.

A
70
Q

What metal products are produced by sintering?

A

Sintering is used to produce cutting tool tips and hard magnetic products.

71
Q

Apart from metals, what other type of material can be sintered?

A

Ceramic materials - low moisture clay powder is pressed into a shape, then fired in a kiln to bond the particles.

72
Q

Forging processes can be carried out either by hand or machine. List five examples of forging processes.

A
  1. Bending
  2. Drawing Down
  3. Punching and drifting
  4. Twisting and scrolling
  5. Drop forging
73
Q

Draw the following hand-forging processes:

Bending, Drawing down, Punching, Scrolling and twisting

A
74
Q

Drop forging is a refining process. A rough shape is required before drop forging. Draw a diagram of the process.

A
75
Q

List seven products that are made by drop forging.

A
  1. Spanners
  2. Hip replacement joints
  3. Cam shafts (automotive)
  4. Stub axles
  5. Gears
  6. G-clamps
  7. Crankshafts
76
Q

Explain using diagrams how drop forging can create a stronger, more durable product.

A