Is polycarbonate stronger than acrylic?

For impact, much stronger: polycarbonate bends and dents where acrylic cracks. Acrylic is harder on the surface, clearer and scratches less.

Why do polycarbonate parts crack around holes?

Usually from stress plus chemicals: cutting oils, threadlockers or cleaning solvents attack stressed areas. Use the right drill, avoid oil coolant and check chemicals before use.

Can polycarbonate be used for machine guards?

Yes, it is the usual material for clear machine guards because it does not shatter. Choose a thickness that matches the guard's risk; it also loses some strength with age, sunlight and coolants, so guards need replacing over time.

Polycarbonate (PC): properties, sheet, machining, uses

Polycarbonate is a clear, very tough engineering plastic: it can take blows that would shatter glass or acrylic. It keeps its strength from about −40 to +115 °C, moulds well and is available as clear sheet and rod. It is used for machine guards, safety covers, lenses, light covers, housings and glazing.

Quick facts

Density: About 1.20 g/cm³
Service temperature: About −40 to +115 °C continuous
Light transmission: About 88–90% (clear grades)
Strengths: Very high impact strength, clear, stiff
Weak points: Scratches easily; cracks with some solvents and oils
Forms: Granules, solid and multiwall sheet, rod

Typical properties

Property	Value
Tensile strength	About 60–70 MPa
Impact strength	Very high (many times acrylic)
Heat deflection temperature	About 125–140 °C
Mould shrinkage	About 0.5–0.7%

Values are typical for unfilled grades. Grades from different makers differ; ask for the supplier's data sheet when it matters.

Polycarbonate or acrylic?

	Polycarbonate	Acrylic (PMMA)
Impact strength	Very high, does not shatter	Lower, can crack
Scratch resistance	Lower (hard-coated grades exist)	Better
Clarity	Very good	Excellent
Typical use	Guards, safety covers, glazing	Display, signage, light diffusers

Working with polycarbonate

Dry granules well before moulding; moisture causes splay and brittleness
Machine with sharp tools and air cooling; avoid oil-based coolants
Drill with low point-angle drills to stop cracking at the exit
Bend sheet cold for simple bends, or heat for tight bends
Clean only with mild soap and water; many solvents cause cracking

Typical uses

Machine guards and safety windows
Light covers, lenses and diffusers
Electrical housings and meter covers
Roofing and glazing sheet
Helmets, visors and riot shields

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Questions

Is polycarbonate stronger than acrylic?: For impact, much stronger: polycarbonate bends and dents where acrylic cracks. Acrylic is harder on the surface, clearer and scratches less.
Why do polycarbonate parts crack around holes?: Usually from stress plus chemicals: cutting oils, threadlockers or cleaning solvents attack stressed areas. Use the right drill, avoid oil coolant and check chemicals before use.
Can polycarbonate be used for machine guards?: Yes, it is the usual material for clear machine guards because it does not shatter. Choose a thickness that matches the guard's risk; it also loses some strength with age, sunlight and coolants, so guards need replacing over time.

The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 18 October 2026.