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page 282

46.2.3 Materials

Materials often come as raw beads. These can be mixed, colored, have other materials added, or reused.

Quite often scrap parts are ground up, mixed with new materials and reused. But, caution is required to reduce contamination.

Common materials are,

Material

Example Applications

Properties

 

 

 

 

Acetals

gears, bearings

tough, natural to opaque white

Acrylics

lenses, reflectors

similar to wood strength, transparent

A.B.S.

appliance housings

tough, opaque

Cellulose Acetate

glass frames

flexible to rigid, tough, transparent

Nylon

bushes and bearings

very tough, almost opaque

Polycarbonate

safety helmets

tough and resilient, transparent

Polyethylenes - low density

kitchen containers

tough and flexible, waxy look

Polyethylenes - high density

milk crates

tough and stiff, waxy look

Polypropylenes

shovel handles

tough and stiff, waxy look

Polystyrenes - general

cosmetic containers

brittle, transparent

Polystyrene - high impact

plastic model toys

tough, translucent

PVC - rigid

pipes

tough, transparent or opaque

PVC - plasticized

kitchen flooring

tough and flexible, transparent or opaque

SAN

disposable cutlery

brittle, transparent

 

 

 

 

46.2.4 Glossary

Barrel - the cylinder the injection screw sits in.

Cavity/Impression - The two or more hollow metal parts that contain the negative of the part. Cold Flow - material that is too cool when injected will get a dull surface finish.

Core - a protruding (or male) mold component. Crazing - a fine mesh of cracks.