What matters
- Translate product language into measurable material requirements.
- Select an exact commercial grade before final shrinkage, texture, color, and validation work.
- Review moisture, fiber orientation, UV, chemicals, flame rating, and recycled content as system constraints.
Write the environment before naming a polymer
- Continuous and short-term temperature, including cleaning and transport excursions.
- Static load, impact energy, fatigue cycles, creep, and assembly strain.
- Chemicals, oils, skin contact, outdoor UV, moisture, and sterilization.
- Flammability, food-contact, medical, electrical, automotive, or customer specifications.
- Color, gloss, texture, transparency, paint, plating, bonding, and laser marking.
- Target cost, annual volume, recycled content, supply region, and approved alternates.
A screening map, not a substitute for grade data
| Family | Often considered for | Design/process caution |
|---|---|---|
| PP | Living hinges, chemical resistance, low density | Creep, shrinkage, paint/bonding |
| ABS | Housings, appearance, general impact | Weathering and some chemicals |
| PC | Impact, heat, transparent parts | Drying, chemical sensitivity |
| PC/ABS | Balanced housing performance | Grade-specific heat/impact |
| PA (nylon) | Wear, strength, mechanical features | Moisture changes dimensions/properties |
| POM | Low friction, gears, precision mechanisms | Processing and bonding limitations |
| TPE/TPU | Grip, seals, flexible overmolds | Hardness, adhesion and compression set |
| PBT/PET | Electrical and dimensional applications | Drying and hydrolysis control |
The grade is the material
A polymer family name is not enough for tooling release. Glass percentage, impact modification, flame package, UV stabilizer, lubricant, color, and recycled content can change flow, shrinkage, warpage, surface, and mechanical behavior.
Use the supplier's current data sheet for the exact grade and request processing guidance. Datasheet values are generated under stated test conditions; they do not automatically predict a rib, snap, seal, or welded assembly in service.
Close the loop with molded evidence
Prototype material, printed material, and machined stock may not match an injection-molded part's orientation, weld lines, residual stress, or surface. Validate the final grade in representative molded geometry, then test the failures that matter: drop, creep, chemical exposure, heat aging, sealing, flame, color, or dimensional stability.
Use this as a design review, not a production release
These guides support early planning. The selected resin supplier, toolmaker, and molder still need to confirm the final geometry, process window, tolerances, safety factors, validation plan, and commercial assumptions for your application.