Thermoplastic olefin (TPO)

TPO (Thermoplastic Olefin)

High impact strength, flexible to semi-rigid; widely used in bumpers and panels.

Processing temperatures

Melt (injection) temperature215 °C
Mold surface temperature35 °C
Ejection temperature80 °C

Typical values. They vary (±) with grade and manufacturer; see the data sheet.

Physical properties (typical)

Density0.89 g/cm³
Shrinkage (flow / cross)1.5 / 1.5 %
Specific heat2 kJ/kg·K
Thermal conductivity0.18 W/m·K
Latent heat of crystallization (approx.)60 kJ/kg

Drying

Usually not required.

For exact conditions see the material data sheet. Drying guide →

Points to watch

  • Visibility of flow marks and weld lines
  • Warpage

Typical use: Automotive bumpers and panels

Defects common with this material

Stress cracking

The part cracks during assembly, on contact with oil/solvent or over time; the crack usually starts at stressed areas.

stress crack · crack · environmental stress cracking

Weld line (knit line)

A line and a weak zone where two melt fronts meet.

weld line · knit line · joining line

Short shot (incomplete fill)

The cavity does not fill completely; the farthest or thinnest area of the part stays incomplete.

incomplete fill · underfill · non-fill

Flash

Plastic escapes through the parting line or around the ejector pins.

flash · overflow · parting line flash

Do the values for this material not match your grade? and we will correct them.