Injection Molding Material Comparison — Property Table
Materials
Why material choice drives cost and performance
The resin you pick decides cycle time, tool wear, post-processing and end-use limits. Below is a working comparison of the plastics we mold most often for buyers weighing spec against budget — drawn from published material data and programs we have run.
The Snapshot
- Service temperature spans the range: ABS ~80–100 °C to PEEK 250–260 °C, with PPS filling the 200–240 °C high-heat band.
- Shrinkage drives DFM: amorphous resins (PC, PMMA, PS) shrink 0.2–0.7%; semi-crystalline (PP, PE, POM, PA) shrink 1.0–3.0% and need more draft.
- Flame class varies by grade: enclosures near electronics often require UL94 V-0 (flame-out ≤10 s, no drips).
- Real programs prove the table: a VR remote in PC+ABS held ±0.04 mm at 800K units/year; a PEEK-class MRI balun ran 15,000+ units/year in PEI.
Full property comparison table
| Material | Density (g/cm³) | Service temp (°C) | Tensile (MPa) | Mold shrink (%) | Melt temp (°C) | Mold temp (°C) | Typical use |
|---|---|---|---|---|---|---|---|
| ABS | 1.05 | 80–100 | 40–50 | 0.4–0.7 | 200–260 | 40–80 | Housings, brackets |
| PP (Polypropylene) | 0.90 | 100–120 | 25–35 | 1.0–2.5 | 200–280 | 20–60 | Hinges, living parts |
| PE (Polyethylene) | 0.94 | 80–100 | 20–30 | 1.5–3.0 | 180–280 | 20–60 | Containers, liners |
| PC (Polycarbonate) | 1.20 | 115–130 | 60–70 | 0.5–0.7 | 280–320 | 80–120 | Transparent, impact |
| POM (Acetal) | 1.41 | 90–120 | 60–70 | 1.8–3.0 | 180–230 | 80–120 | Gears, precision wear |
| PA (Nylon) | 1.14 | 80–120 | 70–90 | 1.0–2.0 | 260–300 | 60–100 | Bearings, structural |
| PEEK | 1.32 | 250–260 | 90–100 | 1.1–1.4 | 350–400 | 160–200 | Aerospace, medical |
| TPU | 1.10–1.20 | 80–120 | 30–50 | 0.8–1.8 | 190–220 | 20–60 | Soft-touch, gaskets |
| PMMA (Acrylic) | 1.18 | 80–100 | 50–70 | 0.2–0.6 | 220–260 | 60–90 | Optics, light pipes |
| PPS | 1.35 | 200–240 | 70–90 | 0.2–0.6 | 300–340 | 120–160 | Chemical, electrical |
| PVC | 1.38 | 60–80 | 40–50 | 0.2–0.5 | 180–210 | 20–60 | Profiles, enclosures |
| PS (Polystyrene) | 1.05 | 70–90 | 40–55 | 0.4–0.7 | 200–260 | 20–60 | Disposable, rigid |
Shrinkage and resin class for DFM
Shrinkage above 2% (PP, PE, POM) demands more generous draft and tighter gate control. Amorphous resins (PC, PMMA, PS) hold tighter tolerances than semi-crystalline ones (PP, PE, POM). For humid environments, absorbent resins (PA, PBT) need drying before molding or you get splay.
A PA6-GF30 HV busbar program at 250,000+ units/year required pre-conditioning because moisture shifted dimensions by 0.2–0.5% — shrinkage and moisture are the two variables that break a tolerance if ignored.
Resin class summary:
- Amorphous (PC, PMMA, PS, ABS): shrink 0.2–0.7%, dimensionally stable, lower warp, but lower chemical resistance and heat.
- Semi-crystalline (PP, PE, POM, PA, PPS, PEEK): shrink 1.0–3.0% (except filled PPS/PEEK at 0.2–1.4%), higher chemical/heat resistance, more warp risk.
Glass-filled grades (PA66-GF30, PPS-GF40) shrink less (0.2–0.5%) but need weld-line and fiber-orientation control — the automotive connector in glass-filled PPS / PA66 held ±0.005 mm critical only with that control.
Heat, flame and moisture handling
Service temperature sets the floor; flame class sets the regulatory bar. UL94 classes in ascending severity: HB → V-2 → V-1 → V-0 → 5VA/5VB. V-0 means flame-out in ≤10 s with no burning drips — the common bar for enclosures near electronics.
- ABS / PP / PC: often V-2 to V-0 by grade.
- PPS / PEI / PEEK: inherently V-0 at 200–260 °C.
- An NEV charging dust cover ran FR-TPU, UL94 V-0 at 500,000+ units/year.
Moisture handling by resin:
- PA66: dry 80 °C, 4 h
- PC: dry 120 °C, 4 h
- POM: dry 80 °C, 2 h
- PPS / PEEK: dry 150 °C, 3 h
Non-absorbent PP / PS / PE / LSR need little or no drying — a scheduling advantage for fast turnaround.
Decision shortcut by function
- Need impact + transparency → PC (melt 280–320 °C)
- Need living hinge → PP (melt 200–280 °C)
- Need wear resistance + tight tolerance → POM or PEEK
- Need soft-touch overmold → TPU / LSR
- Need chemical/heat resistance → PPS or PEEK
- Need lowest cost + light weight → PP (0.90 g/cm³)
Real programs behind the table
| Program | Material | Tolerance | Volume | Lead time |
|---|---|---|---|---|
| Automotive connector | Glass-filled PPS / PA66 | ±0.005 mm | 2M / yr | 10 weeks |
| VR remote housing | PC+ABS / TPE | ±0.04 mm | 800K / yr | 9 weeks |
| Small button | POM / ABS | ±0.03 mm | 5M / yr | 12 weeks |
| Medical ECG button | LSR (medical) | ±0.03 mm | 300K / yr | 7 weeks |
| NEV dust cover | FR-TPU (UL94 V-0) | — | 500K / yr | 6 weeks |
Combining materials: overmolding and inserts
Many production parts are not one resin. Overmolding bonds a soft layer (TPE or LSR) onto a rigid substrate (ABS+PC, PA66), while insert molding casts plastic around a metal part (C11000 copper in the HV busbar, PA6-GF30 at 250,000+ units/year).
Design notes when combining:
- Pick a TPE that bonds to your substrate (PC-ABS, PP) — mismatched chemistry delaminates.
- Account for differential shrink (soft 0.8–1.8% vs rigid 0.4–0.7%) in the overmold gap.
- Insert molding needs ±0.02 mm placement of the metal insert to avoid flash at PPS / PA66 gates.
Regulatory, sustainability and cost reading
Resin choice interacts with compliance:
- RoHS / REACH: restrict heavy metals and SVHCs — relevant for ABS, PC, PPS imported to the EU.
- UL94: flame class on the print for enclosures near electronics (V-0 = flame-out ≤10 s, no drips).
- Recycled content: PP and ABS take post-consumer regrind at 10–30% with minor property loss; PEEK and PPS are rarely recycled in volume.
- Medical / food: LSR and PEI are the biocompatible choices (the MRI balun ran PEI at 15,000+ units/year).
The property table is also a cost map. PP at $1–2.5/kg and 0.90 g/cm³ is the value floor; PEEK at $50–100/kg and 1.32 g/cm³ is the performance ceiling. Between them, ABS ($1.5–3/kg) and PA66 ($3–6/kg) cover most enclosures and structural parts.
When a quote looks expensive, check whether an engineering grade was specified where a commodity resin would do — moving PEEK to PPS can cut resin cost 5–10× while holding 200 °C+ service.
Talk to engineering before you finalize
Upload your 3D file and we return a material recommendation with DFM notes and the right flame class — not just a price. We match resin to load, temperature and budget, with lot-level material certification.