1.16 Metal Processes Flashcards
Describe the term forming
No material is removed, but materials are deformed to produce required shapes
Describe the term redistribution
The material is changed from one form to another, e.g. liquid metal poured into a mould to take a solid shape
Describe the term wastage
Material is cut away to leave the desired shape
State two features of press froming
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
State two features of wrought iron forging
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
State two features of cupping and deep drawing
Process form: Forming
- Starts with a metal blank
- Metal is stretched into shape
- Used for large-scale mass or continuous production
State two features of drop forging
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
State two features of spinning
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
Describe the term addition/fabrication
Process where components and products are made by adding pieces together
State two features of sand casting
Process type: Redistribution
- Labour-intensive process
- Not a high-quality surface finish
- Suitable for one-off or small-batch production
State two features of bending
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
State two features of rolling
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
State two features of gravity die casting
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
State two features of pressure die casting (hot chamber)
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
State two features of pressure die casting (cold chamber)
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
State two features of investment casting (lost wax casting)
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
State two features of low temperature pewter casting
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)
State two features of MIG welding
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
State two features of TIG welding
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)
State two features of oxy-acetylene welding
Process type: Addition
- Uses a steel filler rod
- Useful for quick repair jobs or in remote locations where there is no electric power supply
State the feature of spot welding
Process type: Addition
- Sheet held between two copper electrodes that form a weld when the charged electrodes make contact with the metal
State the feature of soldering
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
State two features of brazing (hard soldering)
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
State the feature of riveting
Process type: Addition
Riveting uses two pieces that are overlapped and drilled. The end of the shaft is then hammered over to join
State the feature of soldering
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
State the feature of pop riveting
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
State the feature of milling
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.
State the feature of turning
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.
State the feature of flame cutting
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
State the feature of plasma cutting
Process type: Wastage
- Plasma is a super-heated ionised gas that is electrically conductive.
- Plasma cutting generates a faster, cleaner cut than flame cutting
State the feature of laser cutting
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.
State the feature of punching/stamping
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.
State the three types of temporary fasteners and joining methods
- Self-tapping screws
- Machine screws
- Nut and bolt
