Injection Molding Technologies — Winter 2019

Define i) Injection Molding ii) Injection cycle iii) Nozzle

Explain the startup and shutdown process of injection molding.

State the advantages and disadvantages of injection molding.

Draw and label the parts of an injection molding machine.

Compare the hydraulic & toggle system for clamping.

Draw and label the parts of a standard screw and explain its terminologies.

List the types of injection machine and explain the single stage plunger type machine.

What is nitriding? Why is it required for screw and barrel?

List the defects found in an injection molded product and give causes and remedies for any two defects.

Explain with a neat sketch the ring type non return valve.

What is purging? When is it necessary in injection molding.

Draw a neat sketch of double toggle clamping mechanism.

Explain the steps of a reciprocating screw type injection molding machine.

What is MFI? How is it important in selecting a material for injection molding.

Draw a PVT diagram and explain it briefly.

Explain with a neat sketch, the process of melting of plastic in a screw.

Explain the terms i) Hold on pressure ii) Back pressure iii) Injection shot capacity.

For a reciprocating screw type injection molding machine, list its injection end specifications.

List the types of nozzles and with a neat sketch explain the Standard nozzle.

Compare hydraulic and electric drive for screw.

Which type of screw is used to process Nylon? Explain it with a neat sketch.

Write a short note on Gas Assisted Injection Molding process.

Why is predrying of a material important before processing? Name the plastic materials which require predrying.

Compare injection molding of thermoplastics with injection molding of thermosets.

List the functions of microprocessor in injection molding machine. Explain open loop & closed loop control.