Processes Flashcards
What is Injection Moulding?
Injection Moulding is the process of injecting molten material under high pressure into a mould or die to achieve a certain form. This process allows a range of complex shapes to be manufactured in high quantities. The quality of the finish means that each piece doesn’t require further finishing
+ Fast Production
+ High Repeatability
+ Precise
+ little to no plastic waste
- High Initial Cost
- Part design and size restrictions
- Plastic resin is poured into a desired shape
- The holding pressure is applied to increase density of the plastic.
- The plastic is then cooled and solidified
- The plastic is carefully released
Draw It
What is Extrusion
Extrusion shapes objects with a fixed cross-section by pushing material through a die. Its used to make complex shapes that re consistent in length.
Pros:
✅ Consistent cross-sectional shape
✅ Efficient for mass production
✅ Low material waste
✅ Can be cut to any length
Cons:
❌ Limited to constant profiles (can’t do complex 3D shapes)
❌ Surface finish may need improving
❌ Dies can be expensive to make
What is Laminating
Thin layers of wood (veneers) are glued together with the grain at right angles, then pressed and sometimes curved in a mould to form a strong sheet or shape (e.g., plywood or bent furniture).
✅ Strong and resistant to warping
✅ Can be moulded into curved shapes
✅ Efficient use of wood – less waste
❌ Can delaminate if exposed to moisture
❌ Glue can contain harmful chemicals
❌ Less natural appearance than solid wood
Spot wielding
Works by placing workpiece between two copper electrodes, current is passed through metals via electrodes causing two sheets to fuse.
+cost effective
+speed,accuracy,reliability
+ welding is localised, rest of material isn’t effected
Casting
Molten metal is poured into a mould cavity (made from sand or metal), where it solidifies into a specific shape — used for parts like engine components or handles.
Pros:
✅ Great for complex shapes
✅ Can be mass-produced
✅ Good material strength
Cons:
❌ Can have air bubbles (porosity)
❌ Moulds may only be used once (e.g. sand casting)
❌ Energy-intensive process
Turning
A lathe spins the material while a cutting tool shapes it — ideal for symmetrical objects like bowls (wood) or shafts (metal).
Pros:
✅ Precise and smooth finish
✅ Good for small batch or one-off items
✅ Quick for round items
Cons:
❌ Only for cylindrical shapes
❌ Needs skilled operator
❌ Some material is wasted
Blow Moulding
A heated plastic tube (parison) is placed in a mould and inflated with air to form hollow shapes like bottles or containers.
Pros:
✅ Ideal for hollow products (bottles, containers)
✅ High speed, low cost
✅ Lightweight final products
✅ Fast and cheap production
Cons:
❌ Limited to hollow shapes
❌ Thin plastic can be weak
❌ Environmental concerns (plastic waste)
