Polycarbonate (PC)

Physical properties

Laser processing

Polycarbonate fumes contain bisphenol-A (BPA), which is an endocrine disruptor. Also releases carbon monoxide and various phenol compounds. Extraction is extremely important, and, if possible, never operate without PPE. Adequate ventilation and HEPA+activated carbon filtration mandatory. Fumes have a sweet, pungent odour.

CO₂: PC cuts very well with CO2 laser. The cut edge is coloured with a slight orange-yellow hue, a characteristic sign of a good PC cut. The edge is slightly melted and glossy. Engraving creates a light grey permanent mark with excellent contrast. Pure PC is the premium choice for laser-cut transparent/lit panels. Maximum thickness for clean cutting: 10mm (with adequate power).

Diode: PC is completely transparent to visible/near-IR diode laser light. Laser diodes (445nm, 455nm, 450nm) pass straight through PC without heating. Only dark-coloured, filled PC (black, dark grey) is significantly cuttable. White PC is partially reflective and extremely challenging. Thickness limit ~2mm with 10W+ diode in multiple passes. Not recommended for production.

Fiber: Not applicable.

CNC / milling processing

Good but requires attention: PC is softer and more flexible than acrylic. When it heats up during CNC milling it behaves like chewing gum, creates a sticky burr, and melts if the bit is inappropriate. O-flute single-flute bits are essential. Recommended chipload: 0.08–0.12mm/tooth (aggressive). High speed (18,000+ RPM) + compressed air to evacuate chips before they re-weld. Cooling is essential.

Plotter and thermoforming

Post-processing

Sanding: PC sands decently but tends to form burrs during dry sanding. For mechanical finishing: grits 320 → 600 → 1200 with wet sanding to disperse heat. Flame polishing does NOT work on polycarbonate—the surface becomes whitish and opaque instead of glossy. For gloss, use vapor polishing (dichloromethane, extremely dangerous) or clear coat application.

Primer: mandatory. Specific PC primer required. Standard primers do not grip and many solvent-based paints attack/craze the PC surface. Acrylic or water-based plastic primer recommended. For solvent paints: always test on a small corner for 24h before application. PC is highly sensitive to solvent stress cracking.

Gluing: The definitive adhesive for PC is dichloromethane (DCM), but DCM is a class-2 carcinogen: it must only be used with full extraction and approved safety protocols. Alternative: UV-curing acrylic resins designed for polycarbonate (e.g., Loctite AA 3492). Cyanoacrylate works but causes stress cracking on the edges; for general bonding use two-part polyurethane or MS polymer adhesives.

Seasoning: PC absorbs a small amount of moisture; for sensitive applications dry at 120°C for 2–4 hours (not higher, as PC can deform). Avoid cleaning with alcohols, ketones, or ammonia—all cause stress cracking. Clean only with water + mild soap. Handle with gloves to avoid fingerprints.

Over time: Outstanding impact resistance, PC is virtually unbreakable (200 times more impact-resistant than glass). However, PC degrades severely under UV light: the surface yellows and becomes brittle after 6–12 months outdoors. UV-stabilised PC grades offer 3–5 years outdoor. For indoor use it is virtually eternal. Absorbs moisture slowly: ~0.15% at 50% RH.

Common defects

• UV yellowing without a protective coating
• Stress crazing (surface micro-cracks) on contact with incompatible solvents
• Brownish, yellowed laser cut edges — not suitable for aesthetic laser finishes

Safety

Recommended PPE: safety_glasses, mask_p2

BPA is released during laser processing. BPA is a known endocrine disruptor. Never process without extraction. Solvent bonding with DCM requires fume extraction. CNC dust is not classified as toxic but fine particles may cause mechanical lung irritation; use at least FFP2 protection.

Availability and formats

Commercial formats: sheets 1–20mm, cellular/twinwall sheets, tubes, round and flat bars

Related materials

Sources

• ISO 7391 — Polycarbonate (PC) moulding and extrusion materials
• Covestro Makrolon — Technical data sheet
• SABIC Lexan — Material safety data sheet