Molding pressure The role of molding pressure is:
- ①Accelerate the flow of plastic in the mold;
- ② Add the compactness of plastic;
- ③ Overcome the pressure generated by the low-molecular substances and other volatiles released by the resin in the polycondensation reaction, so as to avoid defects such as swelling and delamination;
- ④ Close the mold tightly, so that the product has a fixed size, shape and minimum flash;
- ⑤Prevent the product from deforming during cooling.
The size of the molding pressure depends not only on the type of plastic, but also on factors such as mold temperature, product shape, and whether the material is preheated. For the same kind of material, the smaller the fluidity, the faster the curing speed and the greater the compression rate of the material, the greater the molding pressure required; when the mold temperature is high, the product shape is complex, the depth is large, the wall is thin and the area is large, The greater the molding pressure required.
Generally speaking, the appropriate large molding pressure, in addition to the fluidity of large plastics, will also make the product more compact, the molding shrinkage rate will be reduced, and the performance will be improved. However, excessive molding pressure will affect the service life of the mold, large equipment power consumption, and will make The residual internal stress of the product is large, which affects the performance of the product of the plastic mold factory.