Polycarbonate (PC)
Tough and optically clear, with one failure mode that catches almost every first-time machinist.
Stress cracks. It looks like a coolant problem and a tool problem at the same time — the cure is sharp tooling, correct coolant temperature and an anneal before finishing.
Quote a Polycarbonate (PC) partWhat we hold and what we can hold
Figures below are what our shops achieve on prototype quantities. A production order may justify tighter — or looser — tolerances, and that is a conversation, not a default.
| Property | Value |
|---|---|
| Typical use | Transparent covers, guards, lenses, housings, fixtures |
| Machinability | Fair |
| Achievable tolerance | ±0.10 mm typical |
| Typical lead time | 4–7 working days |
| Common grades | PC (Lexan-type) · PC/ABS blend · PC + 10% GF |
| Recommended finishes | Vapour polishing · Bead blasting · Optical polish (clear parts) |
| Suitable processes | 3-axis milling · Vacuum casting · 3D printing (SLA) |
What engineers ask about Polycarbonate (PC)
These are the questions that come up on almost every Polycarbonate (PC) drawing. If your question is not here, send it with the drawing and we will answer it in the quote.
Why did my clear polycarbonate part crack after machining?
Residual stress from machining, sometimes triggered by the wrong coolant or a blunt tool. We anneal the part before finishing and use a stress-free machining strategy.
Can you make a clear optical part?
For a prototype we can machine and polish clear PC to a good optical finish, though it will not match an injection-moulded polished mould. If the part is a lens or a window, vacuum casting or SLA in clear resin is often the better route.
Where this material fits
Surface finishes for Polycarbonate (PC)
When not to use Polycarbonate (PC)
We would rather tell you on day one than ship you a part that was never the right answer. If one of these applies to your project, say so in the enquiry.
- Optical lenses or windows where an injection-moulded polish is required
- Heavily loaded structural parts
- Drawings that do not allow an anneal before finishing