Elastomers and special materials (TPU, TPE, EVA, CA)

CA (Cellulose Acetate)

Flexible, soft-touch or special applications. Hardness (Shore) varies with the grade.

Processing temperatures

Melt (injection) temperature205 °C
Mold surface temperature45 °C
Ejection temperature72 °C

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

Physical properties (typical)

Density1.28 g/cm³
Shrinkage (flow / cross)0.5 / 0.5 %
Specific heat1.5 kJ/kg·K
Thermal conductivity0.19 W/m·K

Drying

Drying is essential for TPU; usually not required for TPE and EVA.

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

Points to watch

  • Low viscosity, risk of flash
  • Sticking in the mold and difficulty in ejection
  • Shrinkage differences and cooling can be long

Typical use: Seals, grips, coatings, shoe soles

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

Other grades in the same family

TPU (Thermoplastic Polyurethane)

Elastic / special210 °C melt · 40 °C mold

TPE-S (Styrene-Based TPE)

Elastic / special205 °C melt · 35 °C mold

EVA

Elastic / special180 °C melt · 30 °C mold

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