In the production of some important injection moulding parts with more precise size requirements, the allowable fluctuation range of each part’s

size is very small, and even requires only one or two filaments of fluctuation.

In the production process, the shrinkage rate of injection parts is usually the main factor affecting the dimensional accuracy of injection parts.

The larger the shrinkage, the worse the accuracy. Therefore, because the shrinkage of PP and POM injection parts is very large, their injection

accuracy is usually poor, which is the reason. The shrinkage of other materials is usually not very small, so the dimensional accuracy of

injection parts is not very high under general injection conditions.

In fact, the shrinkage of the injection parts can be reduced by adjusting the machine, so as to improve the dimensional accuracy of the injection

parts. We only need to increase the injection time and pressure to reduce the shrinkage, shrinkage and size accuracy of injection parts.

Due to the quality limitation of injection moulding machine, the injection pressure can not be adjusted too high, otherwise a large number of

batches will be produced. Therefore, in the common injection moulding machine, the main purpose is to improve the dimensional accuracy of

injection moulding parts by increasing the injection or holding time.