Thermoplastic Elastomer Molding Guidelines
Suggested Remedies
Perform in numerical order by column
Problem
Flash Jetting Knit Lines Non-uniform Color Over Mold Breaks Thru Shorts Surface Sinks Surface Splay Parts Sticking in Cavity Poor Adhesion Warp
Add Mechanical Interlocks 5
Add Surface Texture 5
Add Pneumatic Air Poppets 8
Check for Material Contamination 3 2 6
Check Mold Shut-Off 5
Check Vent Depth 6 6 5
Clean Mold Surface 1 4
Decrease Back Pressure
Decrease Injection Pressure 2
Decrease Injection Speed 4 1 1 3
Decrease Hold Pressure 1 1 5
Decrease Material Temperature 3 3 2 2
Decrease Mold Temperature (Cavity) 3
Decrease Shot Size 2 5 4 1
Dry Material 7 7 1 7
Gate in Thickness Cross Section 6 5
Imcompatible Materials 4 1
Increase Amount of Gates 7
Increase Back Pressure 1
Increase Hold Pressure 4 1
Increase Injection Pressure 3
Increase Injection Speed 2 5 2
Increase Material Temperature 3 4 2 3 4
Increase Mold Temperature 2 3 2 3 2
Increase Shot Size 1 4
Increase Substrate Support 4 3
Move Gate Location 4 5 5 6 6 4
Redesign Ejection Mechanism 7

This information is intended to be used only as a guideline for designers and processors of modified thermoplastics for injection molding. Because injection mold design and processing is complex, a set solution will not solve all problems. Observation on a “trial and error” basis may be required to achieve desired results.

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