Plastic parts are usually specified for one of four reasons: the part must not conduct, must not corrode, must slide without lubrication, or must be chemically inert. All four are things metal does badly, and all four are things the right plastic does well.
Machining plastics is not simply metal work with a softer material. Plastics move with temperature far more than metals do, they deflect under clamping, they chip instead of cutting cleanly if the tool geometry is wrong, and some of them are abrasive enough to wear tooling faster than steel would.
Plastics We Machine
POM-CAcetal copolymer. Dimensionally stable, low friction, easy to machine — the general-purpose engineering plastic, and usually the first choice.
PA6 nylonTough and impact resistant with good wear behaviour, but absorbs moisture and moves as it does. Good for wear strips, rollers and bushings.
PEEKHigh temperature performance with excellent chemical resistance and good mechanical strength. The material for demanding applications, and priced accordingly.
PTFEThe lowest friction of any common plastic, near-universally chemically inert, and very soft. Seals, bearings and liners.
ABSGeneral-purpose and economical, with reasonable impact strength. Used for covers, housings and non-critical components.
Plastic Machining Capabilities
| Materials | POM-C, PA6 nylon, PEEK, PTFE, ABS |
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| Machines | CNC milling and engraving machines, CNC lathes |
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| Machining tolerance | ±0.01 mm where the material and geometry allow |
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| Typical parts | Insulators, bushings, rollers, seals, liners, covers, housings, spacers |
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| Why plastics | Electrical insulation, corrosion resistance, low friction, chemical inertness, weight reduction |
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Machining notes
Plastics grow and shrink more than metals. A plastic part measured cold on a QC bench is not the same size as the same part at operating temperature. On a close-tolerance part, tell us the service temperature and we will account for it — this is the single most common surprise on plastic work.
Tell us if the plastic came from your supplier. Where a customer supplies the material, we machine what we are given. If the material is a specific grade with a mill certificate you need satisfied, say so upfront. Where we source it, we will tell you what we can obtain — and we will not quietly substitute a “similar” grade.
Fits are not the same as metal fits. Plastic parts often need more clearance than the metal equivalent, because they deflect and because printed tolerances carry more slack in practice. If your design comes from a metal version, it is worth mentioning.
A limit worth stating. Not every plastic machines well, and not every grade is something we stock. If your drawing names a specialist material — a filled grade, a glass-reinforced compound, a medical-grade resin with specific documentation — send it and we will confirm feasibility and lead time honestly rather than substitute.
Plastic Machining — Common Questions
Can you machine PEEK?
Yes — PEEK is one of the materials we run. It is the choice where high temperature performance and chemical resistance are both required, and it machines more like a hard engineering plastic than a soft one.
Will the plastic part stay in tolerance at temperature?
Only if the tolerance allows for thermal expansion. Plastics move several times more than metals for the same temperature change, so tell us the service temperature and we will machine accordingly.
Can you supply the plastic material?
We source the grades we list. If your drawing specifies a material we cannot source reliably — or a filled or specialist compound — we will tell you rather than substitute, and you can supply the stock if that is easier.
Are machined plastic parts as precise as metal parts?
The tolerances are achievable, but the practical limits are set by the material: soft plastics deflect under clamping and cut, and thin sections move. Tell us which dimensions are critical and we will confirm what is realistic.