TPE injection molding shrinkage problem solution
The shrinkage of the TPE product means that the surface material at the wall thickness is pulled in due to the volume shrinkage of the product during the cooling and hardening process, thereby causing a dent in the surface of the product.
TPE shrinkage usually has the following reasons:
1 injection molding process problems (such as low injection pressure, insufficient pressure holding time, excessive mold temperature, insufficient cooling time, etc.);
2 structural design problems (uneven thickness of glue position, improper ratio of rib width and glue position thickness, excessive thickness of product glue position, etc.);
3 mold processing problems (the feed port is too small or the flow section is too small, etc.);
4. Material aspects (different shrinkage rate).
TPE shrinking solution:
1, increase the injection pressure, maintain pressure, and prolong the injection time. For tpe plastics with high fluidity, high pressure will produce flash and cause collapse. It should be suitable to reduce the temperature of the material, reduce the temperature of the front section of the barrel and the nozzle, so that the volume change of the melt entering the cavity is reduced, and it is easy to be cold-solid; Viscosity plastics should increase the temperature of the barrel to make filling. The shrinkage time should be extended when shrinkage occurs in the gate area.
2, increase the injection speed can easily fill the parts and eliminate most of the shrinkage.
3, thin-walled parts should increase the mold temperature to ensure smooth flow; wall thickness parts should reduce the mold to accelerate the curing of the skin.
4. Appropriately increase the cooling time and reduce the heat shrinkage. Extending the residence time of the parts in the mold, maintaining a uniform production cycle, increasing the back pressure, and retaining a certain cushion in the front section of the screw are all beneficial to reduce the shrinkage phenomenon.
5, low-precision products should be released early to allow them to slowly cool in the air or hot water, so that the shrinkage depression is gentle and does not affect the use.
6, if the temperature is too high or too low, the pressure will not be effective.
7, the amount of rubber injection is insufficient, increase the amount of glue.
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