16 - Metal processes Flashcards
3 groups for metal processes
- Forming
- Resditribution
- Wastage
Metal processes - forming
Are processes in which no material is removed, but materials are deformed to produce required shapes
Metal processes - redistribution
Are 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 shape
Metal processes - wastage
Are processes that cut away material to leave the desired shape
Types of forming (7)
- Press forming
- Spinning
- Cupping and deep drawing
- Drop forging
- Wrought iron forging
- Bending
- Rolling
Types of redistribution
- Sand casting
- Gravity die casting
- Prssure die casting (hot & cold chamber)
- Investment casting
- Low temperature pewter casting
Types of wastage (4)
- Milling
- Flame cutting
- Plasma cutting
- Laser cutting
Press forming:
- stock form
- products
- Sheet
- Metal seats, car body panels, boxes and containers
Spinning:
- stock form
- products
- Sheet
- Body of stainless steel kettles, saucepans, metal light shades
Cupping and deep drawing:
- stock form
- products
- sheet (round blank)
- tube-like shapes such as fire extinguishers, aerosol cans, drink cans
Drop forging:
- stock form
- products
- Billet
- Spanner’s, pliers and screwdriver shafts
Wrought iron forging:
- stock form
- products
- Bar
- Decorative metalwork such as gate scrolls, decorative fencing
Key features of wrought iron forging (3)
- Uses wrought iron (carbon content less than 0.08%)
- Can be hand or hydraulic press process
- Suitable for one-off or small-batch production
Bending:
- stock form
- products
- Sheet or plate
- Seams on metal edges, bending sheets for product casting or housings
- mainly used for large scale batches in industry
Rolling:
- stock form
- products
Key features of rolling (3)
- Hot rolling metal results in uniform mechanical properties, no deformation or stresses
- 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
Sand casting:
- stock form
- products (7)
- Molten metal from a billet
- Railway carriage wheels, wood working clamps, vices, motor housings, bollards, drain covers, post boxes
Key features of sand casting (3)
- Labour-intensive process
- Not a high-quality surface finish
- Suitable for one-off or small-batch production
Gravity die casting:
- process
- stock form
- products
•
Key features of gravity die casting (2)
- Used for thicker mould sections
- Used for very large-batch and mass production
Pressure die casting (hot chamber):
- process type
- stock form
- products
- Redistribution
- Molten metal from a billet
- Toy cars collectible figures, decorative door knobs and handles
Key features of pressure die casting hot chamber (2)
- Fast process
- Uses for very large batch and mass production
Pressure die casting (cold chamber):
- process type
- stock form
- products
- Redistribution
- Molten metal from a billet
- Toy cars, collectible figures, decorative door knobs and handles
Key features of pressure die casting (cold chamber)
Used for very large-batch and mass production
Investment casting:
- process
- stock form
- products
- Redistribution
- Molten metal from a billet
- Cast jewellery or collectable figures, hip replacement joints
Key features of Investment casting (3)
- Used for intricate or awkward shapes that would be difficult or impossible to Luke using any other casting process
- High quality excellent finish
- Wax patterns are cast from a master mould, repeatable quality process
Low temperature pewter casting:
- process type
- stock form
- products
- Redistribution
- Molten metal from a billet
- Jewellery, key fobs and decorative components
Key features of low temperature pewter casting (3)
- Used for school or college projects
- Can be used with simple MDF moulds
- Suitable for one-off production or small batch
Key features of press forming (3)
- Shapes sheet metal into 3D forms
- Often used in conjunction with robots for lifting sheet into place
- Suitable for mass production or large-scale batch production
Key features of spinning (2)
- Products May show parallel lines where the sheet has been forced onto the mandrel
- Suitable for small-scale batch production
Key features of cupping and deep drawing (4)
- Starts with a metal blank
- Metal is stretched into shape
- High initial tooling cost
- Used for large-scale mass or continuous production
Key features of drop forging (4)
- Used 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 shaped and cooled
- Suitable for mass production
