Injection Molding Materials

Selecting the right material is critical for injection molding success. This guide covers the most common thermoplastics, their properties, and typical applications.

Commodity Thermoplastics

Material	Key Properties	Common Applications
PP (Polypropylene)	Low cost, chemical resistant, fatigue resistant	Containers, automotive interiors, living hinges
ABS (Acrylonitrile Butadiene Styrene)	Good impact strength, paintable, machinable	Consumer electronics, automotive trim, toys
HDPE (High Density Polyethylene)	High strength-to-density ratio, chemical resistant	Bottles, containers, industrial parts
PS (Polystyrene)	Low cost, transparent option available, brittle	Disposable cutlery, CD cases, packaging
PVC (Polyvinyl Chloride)	Flame retardant, weather resistant, rigid or flexible	Pipes, window frames, cable insulation

Engineering Plastics

Material	Key Properties	Common Applications
PA (Nylon 6/66)	High strength, wear resistant, low friction	Gears, bearings, automotive under-hood
PC (Polycarbonate)	High impact strength, transparent, heat resistant	Safety goggles, electronics housings, lenses
POM (Acetal/Delrin)	High stiffness, low moisture absorption, machinable	Precision gears, sliding components, valves
PBT (Polybutylene Terephthalate)	Good electrical properties, chemical resistant	Connectors, automotive electronics, appliances

Material Selection Criteria

• Mechanical requirements: Strength, stiffness, impact resistance, fatigue life
• Thermal requirements: Operating temperature range, heat deflection temperature
• Chemical resistance: Exposure to oils, solvents, cleaning agents
• Environmental conditions: UV exposure, humidity, outdoor weathering
• Regulatory compliance: FDA (food contact), UL (flammability), RoHS
• Cost constraints: Material cost per kg, cycle time impact, scrap rate