Polymer Processes

Question 1

9 polymer processes

Answer 1

Vacuum forming
Thermoforming
Line bending
Lamination
Injection moulding
Blow moulding
Rotational moulding
Extrusion
Compression moulding

Question 2

What are the two types of polymers

Answer 2

Thermosoftening
-remouldable, recyclable

Thermosetting
-impossible to reuse

Question 3

Injection moulding

Answer 3

1. Plastic granules are fed into the hopper.
2. The screw in the chamber below the hopper sends the granules forward.
3. Heated jackets around the screw melt the polymer.
4. The screw winds back and the hydraulic ram comes forward into position.
5. The mould is closed and sealed as the ram forces the melted plastic into the mould.
6. The plastic is allowed to cool and the halves of the mould release.
7. The “sprew” is machined off.

Question 4

Vacuum forming

Answer 4

1. The mould is placed into the former.
2. A sheet of thermo-softening plastic, such as HIPS is clamped over the mould.
3. The plastic is slowly heated to become soften.
4. The mould is raised and the air is sucked, drawing the plastic over the mould to take on it’s shape.
5. The plastic is allowed to cool and then removed from the mould.
6. The edges must then be trimmed and finished.

Question 5

Thermoforming

Answer 5

Thermoforming is a process of heating a thermoplastic sheet to its softening point. The sheet is stretched across a single-sided mold and then manipulated. Then, it cools into the desired shape.

Question 6

Line bending

Answer 6

Sheet of plastic goes over a heated pole once it heats the area u can bend that area

Question 7

Lamination (lay up)

Answer 7

There is a ‘u’ shaped mould and resign, mat and release agent is rolled out evenly over the mould

Question 8

Blow moulding

Answer 8

1. Mould is opened into it’s two halves.
   A hollow tube of polymer known as the parison is heated.
2. The parison is lower into the mould.
   Clues to Blow Moulding:
   Shut Line Sprue Mark Closed neck/hollow shape
   
   3. Mould is clamped shut, leaving only a small hole for the air hose.
3. Air is forced into the mould at high pressure. The plastic is forced to the mould sides and cools.

Question 9

Extrusion

Answer 9

1. A motor turns a thread which feeds granules of plastic through a heater.
2. The granules melt into a liquid which is forced through a die, forming a long
   ‘tube like’ shape.
3. The extrusion is then cooled and forms a solid shape.
4. The shape of the die determines the shape of the tube.

Question 10

Compression moulding

Answer 10

Compression moulding is the oldest commercial plastics moulding process and is mainly used to make products from thermosetting materials. A combination of heat and pressure is used to change the material’s form and chemical structure.

Question 11

Calendaring

Answer 11

Putting a sheet of plastic through rollers to make it thinner