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Polycarbonate (PC)

Polycarbonate is the high-impact, optically clear engineering plastic, famous for near-unbreakable toughness (110% elongation) and glass-like transparency. Stronger (65 MPa) and more heat-tolerant (120°C) than ABS, it machines and molds well and resists chemicals (4.5/5). It's the default when a part must be both clear and impact-resistant.

How Polycarbonate (PC) machines

Rated 3.5/5 and it machines well with care. PC cuts cleanly with sharp tools and moderate speeds, but it's notch-sensitive and can craze or crack at sharp internal corners and heat-affected edges. Keep tools sharp, avoid excessive heat, and use generous radii. Annealing before and after machining relieves stress and reduces cracking; chips clear easily with air.

Manufacturing & processing

Injection molding and CNC machining are its main routes. It must be thoroughly dried before molding, PC hydrolyzes if molded wet, causing splay and brittleness. It bonds with solvents and adhesives, cold-bends, and thermoforms well. Stress relief by annealing prevents environmental stress cracking, especially before solvent contact. Avoid incompatible chemicals that craze it.

Typical applications

Safety glazing, machine guards, and face shields; optical and lighting components, lenses; electronic housings and connectors; riot shields and bulletproof laminates; automotive lighting. Chosen wherever transparency and high impact resistance must coexist, often replacing glass where breakage is a hazard.

When to choose it

Choose PC when you need transparency plus high impact strength, or higher heat resistance than ABS. If the part needn't be clear and cost matters, ABS is cheaper. If you need maximum chemical or scratch resistance, acrylic resists scratching better (but shatters), and PMMA is clearer.

Suitable surface finishes

Common finishes for Polycarbonate (PC): bead blasting, powder coating. Use the finish selector →

FAQ

Why must polycarbonate be dried before molding?
PC is hygroscopic and undergoes hydrolysis when molten if moisture is present, breaking polymer chains. The result is splay marks, bubbles, and brittle, weakened parts. Drying the resin (typically 4+ hours at around 120°C) before molding is mandatory to preserve PC's signature toughness and clarity.
Why does machined polycarbonate sometimes crack?
PC is notch-sensitive and retains molding/machining stresses, so sharp internal corners, heat from dull tools, or contact with incompatible solvents trigger crazing and cracking. Use generous radii, sharp tools, low heat, and anneal to relieve stress before and after machining and before any solvent exposure.
Polycarbonate or acrylic, which should I pick?
Pick polycarbonate for impact resistance and toughness, it bends rather than shatters and tolerates higher heat. Pick acrylic (PMMA) for optical clarity, scratch resistance, and lower cost when impact isn't critical. PC is the safety-glazing choice; acrylic is the display and optics choice.

Property values are typical/nominal for early guidance and vary by temper, grade, supplier and heat treatment. Confirm critical specs against a certified datasheet or with an mfgiq engineer.