How to solve the shrinkage of TPE raw material products is understood after reading it.
Source：德创化工Time：2020-03-28Hits：2636
Shrinkage of TPE products refers to the phenomenon that the surface raw materials at the wall thickness are pulled in due to the volume shrinkage of the products during the cooling and hardening process, resulting in concave marks on the product surface.
TPE shrinkage is usually caused by the following factors:
1, injection molding process problems (such as injection pressure is too low, holding time is not enough, mold temperature is too high, cooling time is not enough, etc.);
2. Structural design problems (uneven glue level thickness, improper ratio of rib width to glue level thickness, too thick product glue level thickness, etc.);
3, mold processing problems (feed inlet is too small or flow channel cross section is too small, etc.);
4. Material (shrinkage difference).
TPE shrink solution:
1, increase the injection pressure, pressure, prolong the injection time. For tpe plastic with high fluidity, high pressure will cause flash and pit collapse. It should be adapted to lower the material temperature, lower the temperature of the front section of barrel and nozzle, so as to reduce the volume change of molten material entering the cavity and facilitate cold solidification. For high viscosity plastics, the barrel temperature should be increased to make mold filling easy. When shrinkage occurs in the gate area, the holding time should be prolonged.
2. Increasing the injection speed can easily fill the product and eliminate most shrinkage.
3, thin-walled parts should increase the mold temperature, ensure smooth flow; For wall thickness parts, the mold should be reduced to accelerate the solidification and setting of the skin.
4. Increase cooling time appropriately to reduce thermal shrinkage. Prolonging the cooling residence time of the workpiece in the mold, maintaining a uniform production cycle, increasing back pressure, and retaining a certain buffer pad in the front section of the screw are all conducive to reducing shrinkage.
5, low precision products should be out of the mold as early as possible to allow them to cool slowly in the air or hot water, which can make the shrinkage depression smooth and does not affect the use.
6, the temperature is too high or too low, will make the pressure compensation can not achieve the effect.
7, glue injection quantity is insufficient, increase the injection quantity.
