DQL10013 - Unit 4: Injection Moulding

What is the principle process for converting plastics into products?

• Extrusion

• Compression Moulding

• Injection Moulding

• Blow Moulding

Which thermoplastic is NOT suitable for injection moulding?

• Polyethylene

• Polytetrafluoroethylene (PTFE)

• Polystyrene

• Polypropylene

What is the first stage in the injection moulding process?

• Plasticising

• After-filling

• Injection

• Cooling

What does the clamping unit in an injection moulding machine do?

• Melts the plastic

• Ejects the molded part

• Injects the plastic

• Holds the mold closed

What is the main advantage of a reciprocating screw injection unit?

• Reduced residence time

• Uneven residence time

• Increased maintenance

• Higher equipment costs

What is the compression ratio (CR) in an injection screw?

• The ratio of the volume at the start of the feed section to the volume in the metering section

• The ratio of the temperature of the melt to the temperature of the mold

• The ratio of the volume of the mold to the volume of the injected plastic

• The ratio of the pressure in the mold to the pressure of the injected plastic

What is one disadvantage of using too much clamping force?

• Improved mold quality

• Reduced venting

• Increased energy consumption

• Faster cycle time

What is a hot-runner system designed to do?

• Increase mold complexity

• Reduce injection pressure

• Increase cooling time

• Eliminate runners

What is the purpose of the after-filling stage in injection moulding?

• To open the mold for ejection

• To inject the melt into the mold

• To maintain pressure to prevent backflow

• To cool the molded part

What is one of the main functions of an injection mold?

• To melt the plastic

• To store raw materials

• To inject the plastic

• To act as a heat exchanger