When a transparent or insulating part must not break, the answer is almost always polycarbonate (PC). With impact strength roughly 250 times that of glass, service temperatures up to ~120 °C and flame-retardant grades available, PC is the standard material for machine guards, equipment windows, electrical enclosures and battery pack insulation.
This guide summarizes the PC properties buyers actually specify, how it machines, and a straight comparison with acrylic — so your next RFQ lands on the right material the first time.
Polycarbonate Key Properties
| Property | Typical value (general-purpose PC) | Why it matters |
|---|---|---|
| Impact resistance | ≈ 250× glass | The defining PC property — safety glazing, guards |
| Density | ≈ 1.20 g/cm³ | Light for its strength |
| Continuous service temperature | ≈ 100 – 120 °C | Well above acrylic and phenolic |
| Heat deflection temperature | ≈ 135 °C | Holds shape under load near heat sources |
| Light transmission (clear) | ≈ 88 – 89% | Slightly below acrylic, still excellent |
| Flame rating | HB standard; V-0 grades available | Needed for electrical enclosures |
| Electrical insulation | Excellent | Widely used for insulating sheets & barriers |
Where Machined PC Parts Are Used
- Machine guards and safety windows on CNC equipment, presses and robotics
- Electrical enclosure panels and terminal barriers (FR grades)
- Battery pack insulation sheets, end plates and cell barriers
- Gears, rollers and wear parts machined from PC rod/sheet
- Anti-vandal glazing and protective visors
For machine guarding, PC is the de-facto standard guard material — verify the required standard for your machinery (e.g., ISO 14120 family) and we manufacture to the specified grade and thickness.
How PC Machines
PC is tough rather than brittle — the opposite failure mode from acrylic. Instead of cracking, PC tends to gum and chatter when machined hot. Our process controls:
- Sharp tooling, high shear — clean cutting before friction heat builds up.
- Air or coolant flood on deeper cuts to keep chips evacuating.
- Workholding with feel — PC marks easily; soft jaws and protective shims on cosmetic surfaces.
- Clamping relief — PC holds threads and clamping loads well; specify thread-milled or heat-insert holes for repeated assembly.
- Chemical caution — PC is vulnerable to stress cracking from some solvents and cleaners; specify compatible cleaning agents for final assembly.
Realistic tolerances for machined PC
| Feature | Standard | Precision option |
|---|---|---|
| Thickness (machined to size) | ±0.15 mm | ±0.05 mm |
| Hole diameter | ±0.10 mm | ±0.05 mm |
| Profile / outline | ±0.20 mm | ±0.10 mm |
| Flatness (per 100 mm) | 0.4 mm | 0.15 mm |
As-supplied sheet thickness runs ±10%, so we machine critical thicknesses to size rather than relying on stock dimensions.
PC vs Acrylic: Which Clear Sheet?
| Requirement | Better choice |
|---|---|
| Impact / safety (guards, windows near moving parts) | PC — decisively |
| Scratch resistance and long-term surface clarity | Acrylic |
| Outdoor UV without coatings | Acrylic (UV-stabilized grades exist for both) |
| Continuous heat up to ~120 °C | PC |
| Flame-retardant requirement (V-0) | PC (FR grades) |
| Cosmetic polished edges, light guides | Acrylic |
Rule of thumb: impact → PC, optics and weather → acrylic, flame + insulation → FR-grade PC. See our acrylic (PMMA) machining guide for the other side of this comparison, and the FR4 fiberglass sheet guide when the part must be a structural electrical insulator rather than transparent.
FAQ
Q: Is polycarbonate really "unbreakable"? A: Practically — for machined guard and window applications it deforms rather than shatters. "Bullet-resistant" glazing is laminated PC for this reason.
Q: Is PC flame retardant? A: Standard grades are HB; FR grades achieve UL94 V-0. Specify the requirement at RFQ — it affects grade selection and price.
Q: Will PC yellow outdoors? A: Uncoated PC yellows with prolonged UV. Use UV-stabilized grades or a hard coat for outdoor service; indoor equipment guards are unaffected.
Q: Is PC electrically insulating? A: Yes — excellent dielectric properties make it a common insulation sheet in switchgear and battery assemblies, and it tolerates more heat than acrylic or phenolic.
Q: Can you match a competitor's PC part? A: Send a sample or drawing; we reverse-engineer, confirm grade (GP/FR/UV), and quote an equivalent with a crossover plan.
Work With the Fabricator Directly
ChaoRong Electronics (潮荣电子， Dongguan, China) precision-machines PC, acrylic, FR4, carbon fiber and electrical board into finished components for B2B customers — machine guards, insulation sheets and precision panels, from prototypes to scheduled production.
→ Request a polycarbonate machining quote · PC product page
Related reading: Acrylic (PMMA) Sheet Machining Guide · FR4 Fiberglass Sheet Guide · Common Mode Choke Selection Guide