ENGINEERING GUIDE
Plastic Material Selection Guide for Injection Molding
Compare thermoplastic material families for injection molding by function, environment, appearance, processing behavior and dimensional needs.
Short Answer
What engineers need to know
Material selection should begin with product requirements rather than a familiar resin name. Mechanical load, temperature, chemicals, moisture, appearance, regulatory needs, tolerance and assembly method all influence the correct grade and tooling strategy.
Select a specific grade, not only a polymer family
Balance performance with molding behavior
Consider moisture, fillers and shrinkage
Validate color, finish and assembly requirements
Translate product requirements into material criteria
Document load, impact, service temperature, chemical exposure, UV, flame behavior, transparency, color, finish, dimensional stability and cost priorities before comparing resin families.
Commodity and general engineering plastics
PP, ABS, PC, PC/ABS, POM, PA and PBT cover many housings and functional components, but grade-level properties and processing requirements vary significantly.
High-performance thermoplastics
PPS, PPSU and PEEK can support demanding temperature, chemical or mechanical requirements when the application and actual processing capability justify them. Tool temperature, material drying, wear and validation need project-specific planning.
Reinforcement changes the system
Glass fiber can increase stiffness and alter shrinkage, flow, surface appearance, wear and anisotropy. Part geometry, gate direction and critical dimensions should be reviewed for the selected filled grade.
Approve the grade before final tooling decisions
Avoid sizing a mold around an approximate resin family when the final grade can materially change shrinkage and processing behavior.
Continue the Engineering Review
Related Topics & Project Evidence
Engineering FAQ
Questions about material selection guide
When should plastic material selection be reviewed?
Review plastic material selection before detailed mold design and steel cutting, while product geometry and tooling decisions can still be discussed efficiently.
Can one rule be applied to every plastic material selection project?
No. Resin, part geometry, appearance, tolerance, production volume and molding conditions must be evaluated together for the specific project.