1.16 Metal Processes

Question 1

Describe the term forming

Answer 1

No material is removed, but materials are deformed to produce required shapes

Question 2

Describe the term redistribution

Answer 2

The material is changed from one form to another, e.g. liquid metal poured into a mould to take a solid shape

Question 3

Describe the term wastage

Answer 3

Material is cut away to leave the desired shape

Question 4

State two features of press froming

Answer 4

Process form: Forming

• Shapes sheet metal into 3D forms
• Often used in conjunction with robots for lifting the sheet into place
• Suitable for mass production or large-scale batch production

Question 5

State two features of wrought iron forging

Answer 5

Process type: Forming

• Uses wrought iron (carbon content less than 0.8%)
• Can be hand or hydraulic press process
• Suitable for one-off or small-batch production

Question 6

State two features of cupping and deep drawing

Answer 6

Process form: Forming

• Starts with a metal blank
• Metal is stretched into shape
• Used for large-scale mass or continuous production

Question 7

State two features of drop forging

Answer 7

Process type: Forming

• Use for products that need to be tough and hard
• Maintains the internal grain structure which retains the strength
• Hot metal billet shaped on an anvil or die and then pressed into shape and cooled
• Suitable for mass production

Question 8

State two features of spinning

Answer 8

Process form: Forming

• Product may show parallel lines where the sheet has been forced onto the mandrel
• Suitable for mass production or small-batch production

Question 9

Describe the term addition/fabrication

Answer 9

Process where components and products are made by adding pieces together

Question 10

State two features of sand casting

Answer 10

Process type: Redistribution

• Labour-intensive process
• Not a high-quality surface finish
• Suitable for one-off or small-batch production

Question 11

State two features of bending

Answer 11

Process type: Forming

• Does not include any punching or trimming of the metal
• Simple bending can be carried out in school or college workshops
• Used for large-scaled batches in industry

Question 12

State two features of rolling

Answer 12

Process type: Forming

• Hot rolling metal results in uniform mechanical properties, no deformation or stress
• Surface is usually coated with carbon deposits, which must be removed using acid pickling
• Cold rolling results in a material that has a tighter tolerance and better surface finish

Question 13

State two features of gravity die casting

Answer 13

Process type: Redistribution

• Lower melt point metals such as aluminium, aluminium alloys and zinc-based alloys
• Relies on gravity to help the metal flow into the mould
• Used for thicker mould sections
• Used for very large-batch and mass production

Question 14

State two features of pressure die casting (hot chamber)

Answer 14

Process type: Redistribution

• Lower melt point metals such as aluminium, aluminium alloys and zinc-based alloys
• Molten metal stored in a shot of molten metal is forced into the die
• Fast process
• Used for very large-batch and mass production

Question 15

State two features of pressure die casting (cold chamber)

Answer 15

Process type: Redistribution

• Lower melt point metals such as aluminium, aluminium alloys and zinc-based alloys
• Molten metal ladled into shot chamber and hydraulically pushed into the chamber
• Used for very large-batch and mass production

Question 16

State two features of investment casting (lost wax casting)

Answer 16

Process type: Redistribution

• Used for intricate or awkward shapes that would be difficult or impossible to mould using any other casting process
• High quality, excellent finish
• Wax patterns are cast from a master mould repeatable quality process

Question 17

State two features of low temperature pewter casting

Answer 17

Process type: Redistribution

• Used for school or college workshops
• Can be used with a simple MDF mould
• Suitable for one-off production or small batch (with aluminium moulds)

Question 18

State two features of MIG welding

Answer 18

Process type: Addition

• Uses an electrode wire
• Suitable for thin-gauge metals, medium carbon steel or aluminium
• Uses an inert gas such as CO2 or argon
• Suitable for one-off fabrication or on an assembly line e.g. car chassis

Question 19

State two features of TIG welding

Answer 19

Process type: Addition

• Uses a filler rod
• Accurate, strong welds but requires high skill levels and is quite a slow method
• Uses an inert gas (argon/helium)

Question 20

State two features of oxy-acetylene welding

Answer 20

Process type: Addition

• Uses a steel filler rod
• Useful for quick repair jobs or in remote locations where there is no electric power supply

Question 21

State the feature of spot welding

Answer 21

Process type: Addition

• Sheet held between two copper electrodes that form a weld when the charged electrodes make contact with the metal

Question 22

State the feature of soldering

Answer 22

Process type: Addition

• Uses a filler material of a lower melting point than the metal being joined. Typically, solders are an alloy of tin and copper

Question 23

State two features of brazing (hard soldering)

Answer 23

Process type: Addition

• Uses a brass filler rod
• Carried out using either oxy-acetylene or a gas and compressed air brazing hearth suitable for one-off production or small batch (with aluminium moulds)
• Used to join dissimilar metals such as mild steel sheet to aluminium copper and nickel

Question 24

State the feature of riveting

Answer 24

Process type: Addition

Riveting uses two pieces that are overlapped and drilled. The end of the shaft is then hammered over to join

Question 25

State the feature of soldering

Answer 25

Process type: Addition Uses a filler material of a lower melting point than the metal being joined. Typically, solders are an alloy of tin and copper

Question 26

State the feature of pop riveting

Answer 26

Process type: Addition Pop riveting uses a rivet gun (or riveting pliers) and a rivet and pin. Good for where the underside of the joint is inaccessible

Question 27

State the feature of milling

Answer 27

Process type: Wastage The milling machine can run in the x-direction (left and right horizontally), y-direction (forward and backward horizontally), and z-direction (up and down vertically) to cut slots, shape edges, or thread holes.

Question 28

State the feature of turning

Answer 28

Process type: Wastage The workpiece is held with a three or four jaw chuck in the headstock whilst the cutting tool moves in two axes.

Question 29

State the feature of flame cutting

Answer 29

Process type: Wastage - Uses oxy-acetylene gas and a special flame-cutting torch to deliver a very intense and focused flame above 3,500°C. - Difficult to maintain a parallel line with high levels of tolerance

Question 30

State the feature of plasma cutting

Answer 30

Process type: Wastage - Plasma is a super-heated ionised gas that is electrically conductive. - Plasma cutting generates a faster, cleaner cut than flame cutting

Question 31

State the feature of laser cutting

Answer 31

Process type: Wastage - More accurate and uses less energy than plasma cutting but cannot cut the same thickness of the material - Lower-powered lasers are used in schools and colleges to cut acrylic sheets and manufacture boards such as MDF and plywood.

Question 32

State the feature of punching/stamping

Answer 32

Process type: Wastage - Uses computer-controlled machines that stamp out sections of sheet material - Suitable for small and medium-size production runs and it is normally used for processing metals from 0.5mm to 6mm thickness.

Question 33

State the three types of temporary fasteners and joining methods

Answer 33

- Self-tapping screws - Machine screws - Nut and bolt