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DFM Guide · Clear Plastic

Optical clarity.
Specific design.
Acrylic. PC. PMMA.

Clear plastic parts demand specific design and processing. Avoid sink marks, weld lines, surface imperfections that destroy optical quality.

01 · Key principles

Key principles.

Wall uniformity

Critical

Variable wall thickness causes sink marks visible through transparent material. Keep walls uniform.

Polishing required

Mold cavity

Mold cavity must be polished to optical finish for clear plastic transparency. SPI A1 grade.

Material moisture

Pre-dry essential

Most clear plastics absorb moisture. Pre-drying before injection essential. Wet material = bubbles.

Gating

Avoid optical zone

Gate marks visible. Place gate in non-optical area, use cold-runner system.

Demolding

Avoid scratches

Surface scratches show. Polished mold + careful demolding + protective film during handling.

Stress whitening

For impact resistant

PC bendable; PMMA scratches and stress-whitens. Choose material per impact requirement.

FAQ

Acrylic vs polycarbonate?

Acrylic (PMMA): scratch-resistant, brittle, cheap, 92% transparency. PC: tough, scratches easier, 88% transparency.

Glass vs plastic optical?

Plastic: lighter, cheaper, formable. Glass: clearer (95%+), more scratch-resistant, brittle.

Edge finish?

CNC machining: edge cloudy. Needs flame-polish or buffing for clear edge. Specify.

Anti-fog coatings?

Add hydrophilic coating to prevent fog. Specialty coating, premium cost.

UV resistance?

PMMA UV-stable. PC yellows with UV unless UV-stabilized. Specify UV grade for outdoor.

Manufacturing volume?

Injection molding economical at 1000+ pieces. CNC for prototypes (1-100). Both can produce optical quality.

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