1.15 Polymer Processes

Question 1

State two features of vacuum forming

Answer 1

• Moulds are relatively easy to make but need a draft angle, air holes, and rounded corners
• Not cost effective for one-off manufacture
• Small-scale batch and mass production

Question 2

State two features of thermoforming

Answer 2

• Like vacuum forming, except an additional mould is pressed on the surface of the polymer sheet at the same time as the vacuum is applied
• Good for fine details such as moulding in logos
• Slow process, used in industrial production

Question 3

State two features of calendering

Answer 3

• Heated rollers squash and stretch the polymer to make it thinner
• Industrial production method, carried out by specialist manufacturers
• Used for continuous production

Question 4

State two features of line bending

Answer 4

• Uses an electrically heated element that provides heat along a line
• Quite slow and labour intensive used in school or college workshops
• Suitable for one-off or limited batch production

Question 5

State two features of lamination (lay-up)

Answer 5

• Requires a former to mould around
• Polyester resin used as the polymer
• A top gelcoat is applied which may contain pigment
• CFRP requires an autoclave for the product to ‘cure’

Question 6

State two features of injection moulding

Answer 6

• Complex 3D shapes can easily be made
• Fast industrial production method
• High initial tooling cost
• Used for large-scale mass or continuous production

Question 7

State two features of blow moulding

Answer 7

• Produces hollow thin-walled components
• High initial tooling cost
• Used for continuous production

Question 8

State two features of rotational moulding

Answer 8

• Seamless hollow components with a large wall thickness
• Mould continuously rotated through heating and cooling
• Large-scale batch or mass production

Question 9

State two features of extrusion

Answer 9

• Like injection moulding expect polymer is forced through a die
• Industrial production method
• Continuous position

Question 10

State two features of compression moulding

Answer 10

• Uses a pre-weighted ‘slug’ of polymer
• Polymer removed from moulds
• Large-scale batch production