Metal Processes Flashcards
Forming
Processes in which no material is removed, but materials are deformed to produce required shapes
Redistribution
Processes where the material is changed from one form to another without loss of material e.g. Liquid metal poured into a mould to take a solid form
Wastage
Processes that involve the removal of material to leave the desired shape
Press forming
Using a punch/male die (made from die steel) to shape sheet metals into 3D forms
Material needs to be ductile
Increases hardness, stiffness and structural strength of the material
Forming
Suitable for mass-production or large scale batch production
Products:
Metal seats
Car body panels
Radiator panels
Spinning
Used to produce 3D curved forms from sheet metal
A rotating mandrel is forced into the sheet metal shaping it
Forming
Suitable for mass production or small scale production
Used for:
Body of stainless steel kettles
Saucepans
Metal light shades
Cupping and deep drawing
A deep drawing punch is used to stretch the metal press blank into shape
Forming
High initial tooling cost
Used for large scale mass or continuous production
Products:
Fire extinguishers
Aerosol cans
Drinks cans
Drop forging
Hot metal billet is shaped on an anvil or die and then pressed into shape and cooled
Forming
Used for products that need to be hard and tough
Maintains the integral grain structure hence retains strength
Suitable for mass production
Used for screwdrivers, pliers and screwdriver shafts
Wrought iron forging
Uses wrought iron (carbon content less than 0.08%)
Forming
Can be hand or hydraulic press process
Suitable for one off or small batch production
Used for decorative metalwork such as gate scrolls and decorative fences
Bending
Using a punch and die to bend the metal to the desired angle
Forming
Can be carried out in a school workshop
Used for large scale batches in industry
Rolling
Used to make a billet thinner and of uniform thickness
Hot rolling - uniform mechanical properties, no deformation or stresses. Carbon deposits on the surface must be removed
Cold rolling - tighter tolerance and better surface finish
Hot rolling - l beams, angle bar, plate and channel and railway tracks
Cold rolling - filing cabinets, chairs, steel drums and containers
Sand casting
Mould is constructed in two halves made out specially treated sand
Redistribution
Halves are put together and runners, risers and vents are added to the top half
Labour intensive process
Not a high-quality surface finish
Suitable for one off or small batch production
Uses:
Railway carriage wheels
Wood working clamps
Vices
Gravity die casting
Molten metal is poured into a two part metal mould using gravity to help the metal flow into the mould
Redistribution
Used for metals with lower melting points - aluminium, aluminium alloys and zinc based alloys
Used for thicker mould sections
Used for large batch and mass production
Products:
Alloy wheels
Engine components
Door knobs and handles
Hot chamber Pressure die casting
A plunger is used to force a shot of molten metal from the chamber up the gooseneck into the die
Redistribution
Fast process used for very large batch and mass production
Used for lower melting point alloys - aluminium, aluminium and zinc alloys
Products:
Toy cars
Collectible figures
Decorative door knobs and handles
Cold chamber pressure die casting
Molten metal ladled into the shot chamber and hydraulically pushed into the die
Redistribution
Used for lower melting point metals - aluminium, aluminium and zinc bases alloys
Investment casting (lost wax casting)
Wax mould is baked in ceramic, molten metal is poured in burning away the wax. The ceramic coating is then smashed open to leave the solid metal
Used for intricate and awkward shapes - difficult or impossible for another casting method
High quality finish and repeatable - wax patterns are cast from a master mould
Products:
Cast jewellery
Collectable figures
Hip replacement joints
