Plastic Materials for Injection Molding
Material selection should start with the part’s job, environment, appearance, production quantity, and approval requirements. The resin family alone is not enough: grade, supplier, color, reinforcement, drying, shrinkage, and processing guidance affect the tool and the part.
A practical material matrix
| Material family | Common decision lens | Tooling and process questions |
|---|---|---|
| ABS | Appearance, impact, general housings | Surface finish, shrinkage, color, weld lines, and cosmetic acceptance |
| PC | Impact, transparency, heat exposure | Drying, stress, gate marks, flow, and appearance control |
| PC/ABS | Balanced impact, stiffness, and processability | Grade, color, heat exposure, shrinkage, and surface standard |
| PP / HDPE | Low density, chemical resistance, living hinges or toughness | Shrinkage, warpage, gate choice, ejection, and fit |
| POM | Low friction, wear, dimensional function | Ventilation, shrinkage, mold temperature, and safe processing |
| PA6 / PA66 / glass nylon | Strength, stiffness, wear, temperature | Moisture, glass-fiber wear, orientation, warpage, and steel choice |
| TPE / TPU | Soft touch, flexibility, sealing or grip | Hardness, substrate, bonding or retention, flash, and demolding |
| PET / PBT | Dimensional, electrical, or engineering applications | Grade, drying, reinforcement, shrinkage, and process window |
| PPS / PEEK | High-performance engineering requirements | Grade-specific temperature, tooling wear, shrinkage, and validation |
From resin choice to mold design
The chosen material can change gate location, cooling balance, draft, ejection, steel selection, surface finish, cycle-time assumptions, and dimensional risk. Share the exact grade or supplier data sheet when available. If the material is not final, identify the candidates so the engineering review can compare their effect on the mold and the finished part.
Material questions to resolve early
Performance
What load, temperature, chemical, impact, wear, friction, insulation, or flexibility requirement must the part meet?
Appearance
What color standard, gloss, texture, polish, transparency, weld-line tolerance, or gate-mark limit applies?
Production
What quantity, cycle, cavity plan, machine fit, drying, handling, and packaging assumptions affect the process?
Compliance
What customer, regional, medical, food-contact, electrical, or other regulatory requirement must the selected grade satisfy? The customer should identify and approve the applicable evidence.
The material page is a decision aid, not a grade approval
Resin names are broad families. Final material and grade selection should be approved by the product owner and checked against the supplier’s technical data, application requirements, and any regulatory obligation. Cavity Mold can review how the specified material affects tooling and molding; it does not make a blanket compliance claim for an unspecified grade.
Need help connecting material to tooling?
Send the resin family or grade, part file, drawing, quantity, and the performance or appearance requirements that matter most.