Plastic CNC Machining
PEEK, Delrin, ABS, nylon, polycarbonate and more — burr-free precision parts in production-grade engineering plastics.
Engineering Plastics, Machined Like We Mean It
Plastic CNC machining is not metal machining with softer stock. Plastics deflect under clamping, melt under dull tools, creep after machining, and absorb moisture from the air. We machine engineering plastics daily — PEEK, Delrin, ABS, nylon, polycarbonate, PTFE, Ultem — with dedicated tooling and stress-relief practices that hold dimensions after the part leaves the machine, not just on it. If a plastic part has ever arrived on size and gone out of tolerance a week later, this page explains how we prevent that.
Plastics We Machine
- PEEK — continuous service to ~480°F (250°C), outstanding chemical resistance, and metal-like stiffness. Medical, aerospace, and semiconductor components. Virgin, glass-filled, and carbon-filled grades. See PEEK machining
- Delrin / POM (acetal) — the precision plastic: dimensionally stable, low friction, low moisture absorption. Bushings, gears, insulators, and wear parts. See Delrin machining
- ABS — economical, tough, and cosmetically forgiving; the standard for machined prototypes and housings. See ABS CNC machining
- Nylon (PA6/PA66) — tough and wear-resistant for rollers, pads, and guides; absorbs moisture, so we machine to compensate and seal parts after machining
- Polycarbonate — impact-resistant and optically clear; machine guards, lenses, and manifolds. Prone to stress cracking — sharp tools and no aggressive solvents
- PTFE (Teflon) — chemically inert and nearly frictionless; seals, seats, and lab components. Very soft — expect generous tolerances
- Ultem (PEI) — high-temperature, flame-rated structural plastic for aerospace and electrical applications
- HDPE, PP, PMMA (acrylic), G10/FR4 — on request
Machining Plastics: What Actually Matters
- Sharp, dedicated tooling — high-rake, polished-flute cutters reserved for plastics; a tool that has cut aluminum will leave burrs and heat-affected surfaces on Delrin
- Heat management — high spindle speeds with moderated feeds, air blast or mist instead of flood coolant where possible; ABS and acrylic smear at surprisingly low temperatures
- Stress relief — PEEK and acetal parts with tight callouts get annealing cycles before finish machining; skip this and dimensions drift days later
- Clamping strategy — plastics deflect under vise pressure and spring back after release. Soft jaws, distributed clamping, and low-pressure fixturing are standard
- Burr control — sharp exits, climb milling, and programmed deburring passes; plastics don't deburr in a tumbler the way metals do
- Moisture compensation — nylon parts are machined with dimensional allowance and measured at controlled humidity when the drawing is tight
Tolerances and Finishes
Plastics move with temperature and humidity, so tolerances are quoted per material and feature: typically ±0.005 in (±0.13 mm) general, to ±0.002 in (±0.05 mm) on critical features in stable materials like PEEK and Delrin, measured at room temperature. PTFE and HDPE hold looser — we'll tell you what's realistic on your drawing.
Finishes are mostly as-machined: bead blast for a uniform matte, polishing and flame polishing for clear polycarbonate and acrylic, and laser marking for identification. No anodizing, no plating — if the part needs a metallic finish, that's a design conversation.
Typical Plastic Parts
Insulators and electrical components, bushings and wear pads, gears and rollers, medical device components, semiconductor handling parts, manifolds, and functional prototypes where the production intent is molded plastic but the geometry must be proven in the real material.
What to Specify on the Drawing
Name the exact resin and grade — “black plastic” is not a spec, and POM-C versus POM-H or virgin versus filled PEEK changes both price and performance. Mark which dimensions are critical; we’ll hold those and let the rest run to standard tolerance, which keeps cost down. If the part must survive a specific temperature or chemical, put it on the drawing so we can flag material risks before cutting. And if the production intent is injection molding, tell us — we’ll point out geometry that machines fine but won’t mold.
Plastic Machining — Capability Summary
| Capability | Specification |
|---|---|
| Materials | PEEK, Delrin/POM, ABS, nylon PA6/PA66, polycarbonate, PTFE, Ultem, HDPE, PMMA, G10 |
| General tolerance | ±0.005 in (±0.13 mm); to ±0.002 in (±0.05 mm) in PEEK/Delrin, room-temp measurement |
| Stress relief | Annealing cycles available for PEEK and acetal on tight-tolerance parts |
| Finishes | As-machined, bead blast, polishing, flame polishing (clear parts), laser marking |
| Batch range | 1 pc prototype to 10,000+ pcs production |
| Typical lead time | Prototypes from 3 days; production typically 2 weeks |
Quote Your Plastic Parts
Send STEP files and drawings with the plastic specified — or describe the application and we'll recommend one. Quotes back in 1–2 business days. More materials on the materials page.
Quote Your Plastic Parts
Send STEP files and drawings with the plastic specified — or describe the application and we'll recommend one. Quotes back in 1–2 business days.
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