M&P chapter 5

Question 1

Plastics that soften with increasing temperature
and regain rigidity as the temperature is decreased are called:

Answer 1

Thermoplastic.

Question 2

Plastic materials that cannot be returned to their original state after they have been exposed to higher temperatures during the manufacturing process are referred to as:

Answer 2

Thermosetting.

Question 3

The greatest variety of plastics comprises:

Answer 3

Synthetic materials.

Question 4

The most important area of plastic processing is:

Answer 4

Matched die molding.

Question 5

Compression molding, cold molding, transfer molding, and injection molding are all examples of what type of plastic processing?

Answer 5

Matched die molding.

Question 6

__________ materials may be held in the softened condition for prolonged periods of
time with little or no chemical change.

Answer 6

Thermoplastic

Question 7

The high pressures required by compression molding, together with the low viscosity of most thermosetting materials, require that the mold halves have fitting clearances on the order of:

Answer 7

0.025 mm (0.001 in.)

Question 8

The sprue and runner system, or “cull”, that is produced during the transfer molding process:

Answer 8

Must be removed and cannot be reused.

Question 9

The injection molding process for thermosetting plastics is referred to as:

Answer 9

Jet, flow, or offset molding.

Question 10

A low tooling cost procedure restricted to thermosetting resins used for low production of jewelry, novelty items, laboratory specimens,
and similar parts is called:

Answer 10

Casting of plastics.