Factors affecting roundness of injection molding parts and solutions

The roundness of injection molding parts has always been an important issue in the production of plastic products. The existence of roundness error may lead to poor appearance, performance deterioration, or even normal use of the product. This paper will discuss the factors affecting the roundness of injection molded parts and the solutions.

The factors that affect the roundness of injection molding parts mainly include mold structure, material and technology. The unreasonable mold structure is one of the main reasons for the roundness of injection molded parts. For example, improper mold design will lead to uneven pressure, uneven plastic flow and other problems, and then lead to the roundness error of injection molding parts. Poor material quality is also one of the causes of roundness error. Such as materials containing impurities, decomposition, etc., will lead to uneven plastic flow, and then affect the roundness of injection molding parts. Improper setting of process parameters is also one of the causes of roundness error. Such as too high or too low temperature, insufficient or excessive pressure, will lead to uneven plastic flow, and then affect the roundness of injection molding parts.

The solution on the process is to adjust the product well by adjusting the process. There are three elements for this bad roundness:

The first one is the rate of fire, and the higher the rate of fire, the greater the difference between the vertical and the tangential contraction in this direction, so the higher the rate of fire, the more ellipse it should be.

The second pressure holding time, long pressure holding time can make the product more tight, also can make up for its anisotropy in the direction of the rate of fire, so long pressure holding time can reduce its ovality, can reduce the bad tendency of the roundness, but will make the size of the whole product change.

The third is the mold temperature, where the four sides of the mold temperature is high, it will collapse to which side, where the mold temperature is cold, its shrinkage rate is relatively light, that way, it will also bring changes in roundness.

The roundness of injection molded parts is a complicated and important problem. By analyzing and adjusting the mold structure, material and process, the roundness error can be solved effectively and the product quality and production efficiency can be improved. At the same time, for the specific problems in the actual production, it is necessary to take corresponding measures based on the actual situation to ensure the quality and performance of the product to reach the best state.