Dimensional accuracy of plastic injection molded parts

When ABS plastic molding manufacturers produce certain important injection molded parts with relatively precise dimensional requirements, the range of fluctuation allowed for each part is very small, and even requires only one or two microns of fluctuation.

In the production process, the main factor that usually affects the dimensional accuracy of injection molded parts is the shrinkage rate of the injection molded parts. The greater the shrinkage rate, the worse the accuracy. Therefore, since the shrinkage rates of ABS and POM injection molded parts are very large, their injection molded parts are usually poor in accuracy. The shrinkage rates of other materials are usually not very small, so the dimensional accuracy of injection molded parts is not very high under general conventional injection molding conditions.

In fact, the shrinkage rate of injection molded parts can be reduce

d by adjusting the machine, thereby achieving the purpose of improving the dimensional accuracy of injection molded parts. We only need to greatly increase the time and pressure of injection or holding pressure to reduce the shrinkage of injection molded parts, significantly reduce the shrinkage rate, and naturally improve the dimensional accuracy.
Due to the quality limitations of the injection molding machine, the injection pressure cannot generally be adjusted too high, otherwise a large number of batches will be generated. Therefore, on commonly used ordinary injection molding machines, the purpose of improving the dimensional accuracy of injection molded parts mainly relies on increasing the injection or pressure holding time.

In order to ensure the dimensional accuracy of injection molded parts, the accuracy of the mold is the first condition that needs to be guaranteed, and it is more important to choose a stable and reliable (with little parameter fluctuation) and sufficient pressure injection molding machine for production.

Some of the newly developed high-precision injection molding machines are actually high-pressure injection molding machines with stable performance and extremely high parameter accuracy. It is reported that the shrinkage rate of its injection molded parts can be almost 0, that is, the size of each injection molded part is almost the same as the size of the cavity, and the fluctuation range is only about a trace, and the accuracy is extremely high.