The shrinkage rate of plastic refers to the percentage difference between the size of the plastic product at the molding temperature and the size after being taken out of the mold and cooled to room temperature. It reflects the degree of reduction in size of the plastic part after being taken out of the mold and cooled.
Factors affecting plastic shrinkage include plastic varieties, molding conditions and mold structure.Different polymer materials have different shrinkage rates. The shrinkage rate of plastics is also related to the shape of the plastic part, the complexity of the internal structure, and whether there are inserts.
There are the effects of the molding process on the shrinkage of plastic products.
1.The molding temperature remains unchanged,the injection pressure increases and the shrinkage rate decreases.
2.Keeping the pressure increasing, the shrinkage rate decreases.
3.As the melt temperature increases, the shrinkage rate decreases.
4.The mold temperature is high, and the shrinkage rate increases.
5.The holding time is long and the shrinkage rate is reduced, but the shrinkage rate is not affected after the gate is closed.
6. Long cooling time in the mold reduces shrinkage.
7.The injection speed is high, the shrinkage rate tends to increase slightly, and the effect is small.
8. The molding shrinkage is large, and the post shrinkage is small. After the contraction is big at the beginning, it is stable for about a week.
Post time: Jul-25-2020