Injection Molding Materials

Typical applications

• General-purpose housings and enclosures (ABS, PP, PE)
• High-strength structural components (glass-filled nylon, PC)
• Chemical- or fuel-resistant components (acetal, certain nylons)
• Soft-touch and sealing features (TPE, TPU)

Process overview

1. 1

   You specify the resin and grade

   Material selection is the customer's decision. If you need help arriving at it, we can point you to an independent lab or design engineer — see Engineering Support.

2. 2

   We confirm processability

   We review how the specified resin will flow, shrink, and cool in your part geometry, and flag features that will be difficult to mold in it.

3. 3

   Choose the color route

   Color concentrate blended here, pre-colored resin from a coloring house, or a standard base resin color — usually a cost decision.

4. 4

   Confirm on the tool

   Shrink, warp, and cosmetic result are verified on first articles from the actual tool before production release.

Materials

• Nearly all thermoplastics — ABS, MABS (clear ABS), PP, PE (LDPE, LLDPE, HDPE), nylon (PA6, PA66, PA12) and glass-filled grades, PC and PC/ABS, acetal (POM), PS, acrylic, TPE/TPU, and more
• Glass fill up to roughly 30–35% — above that we decline, because heavily filled resins damage screws and barrels
• NOT processed: thermoset materials
• NOT processed: rigid (hard) PVC
• NOT processed: liquid silicone rubber (LSR)
• NOT processed: PEEK
• Color: nearly any color, with matching to standard color charts
• Color route 1 — concentrate blended at Wrex (typically lowest cost, most flexible)
• Color route 2 — pre-colored resin from a coloring house (best shot-to-shot consistency)
• Color route 3 — standard base resin color where one suits the part (cheapest and fastest)

Part design considerations

• Shrink rate varies by resin and glass loading — tooling is cut to the shrink of the grade you approve, so a late resin change can mean reworking steel
• UV and chemical exposure in the end-use environment narrows the practical resin list quickly
• Cosmetic requirements (gloss, texture, color) can rule out certain resins or grades
• Send a physical color standard when appearance matters — gloss and texture shift how a color reads

DFM guidance

• Settle the resin before finalizing wall thickness and draft — shrink and flow behavior differ meaningfully between families
• Confirm any regulatory requirement (e.g., UL flame rating, biocompatibility) with your material supplier before tooling, not after first article
• Tell us at RFQ if you need RoHS certificates — we can provide them on request (we do not offer or monitor REACH)

Quality controls

• Certificate of conformance / material traceability available on request
• Lot documentation for regulated applications

Secondary operations available

• In-house color blending
• Third-party plastic material analysis (independent laboratory)
• Regrind policies discussed and agreed per program

Frequently asked questions