Injection Molding Guidelines for TPE Materials

TPE is a widely used soft elastomer with good elasticity, touch, and processability. However, it is sensitive to temperature, shear, and cooling. Stable production requires careful control of material, temperature, pressure, mold design, and operation.

Material Handling

Most TPE grades have low moisture absorption.

Usually no drying required unless stored in high humidity.

If drying is needed: 60–80°C for 1–2 hours.

Clean the barrel before production to avoid mixed materials.

Recycled material ratio: 10–20% to maintain elasticity.

Temperature Settings

TPE is highly temperature-sensitive.

Barrel temperature: 160–200°C, lower for softer grades.

Nozzle temperature slightly lower to prevent drooling.

Mold temperature: 30–50°C for balanced surface and cooling.

Avoid overheating, which causes sticking, odor, and decomposition.

Injection Pressure and Speed

Stable filling reduces defects.

Use moderate pressure to avoid flash or internal stress.

Medium to high speed for complete filling.

Avoid excessive shear heat from high speed.

Shorten packing time and pressure to prevent deformation.

Mold Design Requirements

Good mold design prevents sticking and poor quality.

Sufficient venting to avoid burns and trapped air.

Smooth runners and gates for smooth flow.

Large-area ejection: ejector plates or air ejection preferred.

Polished cavity surface improves demolding.

Cooling and Demolding

Adequate cooling is critical for TPE.

Ensure full cooling before ejection to avoid sticking.

Use water cooling circuits uniformly distributed.

Minimize release agent; use only non‑silicone types.

For sticky grades, use DLC or nano-coatings.

Common Defects and Solutions

Sticking: Lower temperature, increase cooling, improve mold surface.

Sink marks: Optimize holding pressure and cooling.

Weld lines: Improve venting, increase temperature slightly.

Deformation: Extend cooling, use fixture cooling.

Separation or peeling: Clean barrel, avoid material mixing.

TPE injection molding relies on stable temperature, balanced pressure, sufficient cooling, good venting, and smooth ejection. With proper parameters, high yields and consistent quality can be achieved.