Polymer Processes Flashcards
(7 cards)
1
Q
Injection moulding
A
- Plastic granules are fed into the hopper
- The screw in the chamber below the hopper sends granules foward
- Heated jackets around the screw melt the polymer
- The mould is closed and sealed as the ram forces the melted plastics into the moud
- The plastic is allowed to cool and the halbes of the mould release
2
Q
Vaccum forming
A
- The mould is placed into the former
- A sheet of thermosoftening plastic, such as HIPS is clamped over the mould
- The plastic is slowly heated to become soften
- The mould is raised and the air is sucked, drawing the plastic over the mould to take on its shape
- The plastic is allowed to cool the removed from mould, then edges are trimmed and finished
3
Q
Thermo forming (industrial process)
A
- Thermoforming is a process of heating the thermplastic sheet to its softening point. The sheet is stretched across a singlr sided mold and then manipulated, the it cools into the desiered shape
4
Q
Line Bending
A
- Line or strip bending is a process used to form straight, small curvature bends in the thermoplastic sheet material such as acrylic and ABS. Line bending is carried out boht in school and industrial situations
5
Q
Blow Moulding
A
- Mould is opened into its two halves, a hollow tube of polymer known as the parison is heated
- The parison is lowered into the mould
- Mould is clamed shut, leaving only a small hole for the air hose
- Air is forced into the mould at high pressure. The plastic is forced to the mould sides and cools
6
Q
Extrusion
A
- A motor turns a thread which feeds granules of plastic through a heater
- The grnalues melt into liquid which is forced though a die, forming a long tube like shape
- The extrusion is then cooled and forrms a solid shape
- The shape of the die determines the shape of the tube
7
Q
Calendering
A
- Is a speciality process for high volume, high quality plastic film and sheet, mainly used for PVC as well as for other certain other modified thermoplastics
