PBT Plastic Injection Molding Parameters

Polybutylene terephthalate (PBT), classified alongside PET as a thermoplastic polyester, finds extensive application across multiple industries. Its uses span household appliances (including food processing blades, vacuum cleaner components, and small appliance housings), electrical components (switches, motor housings, and computer keyboard keys), and automotive applications (radiator grilles, body panels, and wheel covers).

Critical injection molding parameters for PBT engineering plastics include:

Melt temperature: 250-260°C (narrow processing window)

Barrel temperature: 210°C

Mold temperature: 60-80°C

Injection pressure: 100-140 MPa

Holding pressure: 50-60% of injection pressure

Back pressure: 5-10 MPa (prevents frictional heating)

Injection speed: High velocity required due to rapid solidification

Screw speed: Maximum linear speed 0.5 m/s

Drying: 4 hours at 120°C

Regrind usage: Maximum 10% for flame-retardant grades, 20% for standard grades

Shrinkage: 1.4-2.0% (reduced to 0.4-0.6% with 30% glass fiber)