POM (Acetal, Pure Homopolymer/Copolymer)
High stiffness, low friction, wear resistance, dimensional stability; the standard choice for gears and sliding elements.
Processing temperatures
| Melt (injection) temperature | 210 °C |
|---|---|
| Mold surface temperature | 90 °C |
| Ejection temperature | 115 °C |
Physical properties (typical)
| Density | 1.41 g/cm³ |
|---|---|
| Shrinkage (flow / cross) | 2 / 2 % |
| Specific heat | 1.5 kJ/kg·K |
| Thermal conductivity | 0.23 W/m·K |
| Latent heat of crystallization (approx.) | 195 kJ/kg |
Drying
Usually not required; a short drying is recommended for some grades.
Points to watch
- Excess temperature and residence time release formaldehyde (degradation)
- Contact with PVC and contamination are dangerous (they accelerate degradation)
- Shrinkage differences, sink marks (thick sections)
Defects common with this material
Warpage
The part distorts or bends after it leaves the mold.
Sink mark
A dent on the surface opposite a thick section; the surface is drawn inwards.
Dimensional variation and shrinkage differences
Part dimensions fall outside the tolerance or vary from cycle to cycle.
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.
Other grades in the same family
POM (Hostaform)
205 °C melt · 90 °C moldPOM + GF10
212 °C melt · 95 °C moldPOM + GF25
217 °C melt · 100 °C moldDo the values for this material not match your grade? and we will correct them.