how to improve injection tolerence

how to improve injection tolerence

In the production of some important injection molded parts with precise size requirements, the allowable fluctuation range of the size of each part is very small, even only one or two um is required.

In the production process, the main factor that usually affects the dimensional accuracy of injection molded parts is the shrinkage of injection molded parts. The greater the shrinkage, the worse the accuracy. Therefore, due to the large shrinkage of PP and POM injection parts, the poor precision of their injection parts is the reason. The shrinkage rate 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, it can reduce the shrinkage of injection molding parts by adjusting the machine, so as to improve the dimensional accuracy of injection molding parts. We only need to greatly increase the injection time and pressure, which can reduce the shrinkage of the injection parts, obviously reduce the shrinkage, and naturally improve the dimensional accuracy.
Due to the quality limitation of the injection molding machine, the injection pressure can not be adjusted too high, or a large number of tips will be produced. Therefore, in the common injection molding machine, it mainly depends on increasing the injection time or holding time to improve the dimensional accuracy of the injection parts.
In order to ensure the dimensional accuracy of the injection parts, the accuracy of the mold is the first condition to be guaranteed, and it is more important to choose a stable and reliable injection molding machine (with little parameter fluctuation) with sufficient pressure to produce.
Some of the new high-precision injection molding machines are actually high-pressure injection molding machines with stable performance and high parameter accuracy. According to the introduction, the shrinkage rate of the injection molded parts can be almost 0, that is to say, the size of each injection molded part is almost the same as the size of the cavity, the fluctuation range is only about a trace, and the precision is extremely high.