Request a Quote →

Acrylic (PMMA) CNC Milling & Optical Diamond Machining

Acrylic (Polymethyl Methacrylate / Plexiglass) offers crystal-clear 92% light transmittance, exceptional UV weatherability, and high surface hardness for optical lenses and light guides.

Engineering Specifications & Parameters

Density 1.19 g/cm³
Hardness M-95 Rockwell M
Machinability 85% (Cast Acrylic Recommended)
Refractive Index 1.491
Tensile Strength 75 MPa
Light Transmittance 92% (Clearer than standard glass)

Cast vs Extruded PMMA Machining

Always choose Cast Acrylic for CNC milling. Extruded acrylic has a lower molecular weight, causing it to gum, melt, and chip under cutting tool shear stress.

Tooling & Optical Surface Guidelines

  • Tooling: Single-flute polished upcut O-flute carbide router bits or Single-Crystal Natural Diamond (MCD) tools.
  • Cutting Speed: High RPM (18,000–24,000 RPM) with fast linear feed (3000–5000 mm/min) to eject heat within large, clean chips.
  • Cooling: Continuous cold compressed air blast. Avoid alcohol or chemical solvents that cause instant stress cracking.

Frequently Asked Questions

Why is cast acrylic superior to extruded acrylic for CNC milling?

Cast acrylic has higher molecular weight, resisting melting and chipping while achieving crystal-clear finishes during high-speed routing.

Can machined acrylic surfaces be polished to complete optical clarity?

Yes, using sequential fine diamond polishing or flame polishing for external edges and solvent vapor polishing for complex internal channels.