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.
