PMMA (Acrylic / Plexiglas)
Very high transparency and gloss, relatively scratch-resistant, brittle.
Processing temperatures
| Melt (injection) temperature | 240 °C |
|---|---|
| Mold surface temperature | 60 °C |
| Ejection temperature | 90 °C |
Physical properties (typical)
| Density | 1.18 g/cm³ |
|---|---|
| Shrinkage (flow / cross) | 0.4 / 0.4 % |
| Specific heat | 1.3 kJ/kg·K |
| Thermal conductivity | 0.19 W/m·K |
Drying
Drying is required (about 80 °C, a few hours).
Points to watch
- Internal stress and stress cracking
- Moisture causes bubbles
- Cooling is slow and the mold temperature determines the optical quality
Defects common with this material
Splay (silver streaks)
Fine silvery streaks on the part surface in the flow direction.
Brittleness / low impact strength
The part breaks more easily than expected; sometimes the surface looks fine.
Stress cracking
The part cracks during assembly, on contact with oil/solvent or over time; the crack usually starts at stressed areas.
Weld line (knit line)
A line and a weak zone where two melt fronts meet.
Short shot (incomplete fill)
The cavity does not fill completely; the farthest or thinnest area of the part stays incomplete.
Flash
Plastic escapes through the parting line or around the ejector pins.
Do the values for this material not match your grade? and we will correct them.