Reference & Charts
Engineering Plastics
Typical properties of the plastics machine shops cut most — Acetal, Nylon, UHMW, PTFE, polycarbonate, PEEK, HDPE, PVC, acrylic, and ABS. Compare density, strength, service temperature, moisture absorption, and machinability, with a spec sheet and typical uses for each.
10 entries · Last verified: 2026-07-10
Choosing a machining plastic is a trade between stiffness, toughness, temperature, chemical resistance, moisture stability, and cost. Acetal is the tight-tolerance default; nylon is tougher but moves with moisture; UHMW and PTFE win on wear and friction; polycarbonate and acrylic cover impact and clarity; PEEK is the high-temperature performer; HDPE, PVC, and ABS are the low-cost utility choices. The values below are typical for a common unfilled grade — fillers (glass, carbon, bronze, MoS₂) shift them substantially.
| Engineering Plastic | Polymer | Density(g/cm³) | Tensile(MPa) | Max service(°C) | Water abs.(%) | Machinability |
|---|---|---|---|---|---|---|
| Acetal (POM / Delrin) | Polyoxymethylene | 1.42 g/cm³ | 70 MPa | 90 °C | 0.2 % | Excellent |
| Nylon 6/6 | Polyamide 6/6 | 1.14 g/cm³ | 80 MPa | 100 °C | 1.2 % | Good |
| UHMW-PE | Ultra-high-mol.-wt. PE | 0.93 g/cm³ | 21 MPa | 80 °C | 0.01 % | Good |
| PTFE (Teflon) | Polytetrafluoroethylene | 2.17 g/cm³ | 25 MPa | 260 °C | 0.01 % | Fair |
| Polycarbonate (PC) | Polycarbonate | 1.2 g/cm³ | 65 MPa | 120 °C | 0.15 % | Good |
| PEEK | Polyether ether ketone | 1.32 g/cm³ | 100 MPa | 250 °C | 0.1 % | Good |
| HDPE | High-density PE | 0.95 g/cm³ | 30 MPa | 80 °C | 0.01 % | Good |
| PVC (Rigid, Type I) | Polyvinyl chloride | 1.42 g/cm³ | 52 MPa | 60 °C | 0.04 % | Good |
| Acrylic (Cast, PMMA) | Poly(methyl methacrylate) | 1.19 g/cm³ | 72 MPa | 80 °C | 0.3 % | Good |
| ABS | Acrylonitrile butadiene styrene | 1.05 g/cm³ | 43 MPa | 85 °C | 0.3 % | Good |
Select a engineering plastic for its full spec sheet.
Frequently asked
- Acetal or nylon — which should I machine?
- Acetal (Delrin) for tight tolerances and dimensional stability: it barely absorbs moisture and machines beautifully. Nylon when you need more toughness and wear resistance and can tolerate movement — it absorbs moisture (parts grow up to a few tenths of a percent), so allow for it on close-tolerance parts.
- Which plastic has the best wear resistance and lowest friction?
- UHMW-PE for abrasion and sliding wear at low cost; PTFE for the lowest friction and chemical inertness (but it's soft and creeps). Filled grades — oil-filled nylon, bronze-filled PTFE — combine low friction with more load capacity.
- Are these exact values?
- They're typical published values for a common unfilled grade. Real properties depend on the specific grade, fillers, moisture content, and supplier — always verify against the manufacturer's datasheet for design-critical work.
Sources
- Manufacturer datasheets (typical properties for common unfilled grades)
- ASM International — Engineering Plastics (Engineered Materials Handbook)