How to solve the shrinkage printing on the surface of injection molding products? Forwa Injection molding factory to tell you

Forwa is a plastic injection molding factory, specializing in the processing of automotive plastic parts, industrial electrical plastic parts, smart home plastic products. In the production process, encountered a lot of problems, summed up a lot of experience, the injection molding engineer of Forwa to share with you how to solve the shrinkage printing on the surface of injection molding products?

     1. Uneven wall thickness of injection molded products causes uneven surface shrinkage, resulting in shrinkage printing.

     2. Improper control of forming conditions. Appropriately increase the injection pressure and injection speed, increase the compression density of plastic, prolong the injection and pressure holding time, compensate for the shrinkage of plastic, increase the injection buffer. But the holding pressure should not be too high, otherwise it will cause convex marks.

      If the dent and shrinkage printing occurs near the gate, it can be solved by extending the pressure holding time; When the injection molding products in the wall thickness of the depression, should be appropriate to extend the injection molding products in the mold cooling time; If the insert around due to the local shrinkage of plastic caused by depression and shrinkage, this is mainly due to the temperature of the insert is too low, should try to improve the temperature of the insert; If the surface of plastic parts is depressed due to insufficient injection, the amount of injection should be increased. In addition, the injection product in the mold cooling must be sufficient.
     3. Mold defects. According to the specific situation, the section of the gate and the runner should be appropriately expanded. The gate position should be set in the symmetrical place as far as possible, and the feed port should be set in the thick wall of the injection molding product. If the dent and shrinkage imprint occurs far away from the gate, it is generally due to the poor flow of plastic in a certain part of the mold structure, which prevents the pressure transfer.

      To this end, the structure size of the mold pouring system should be appropriately expanded, and it is best to extend the runner to the part of the depression. For injection molding products with thick wall, fan gate should be preferred.


      4 .plastic materials do not meet the molding requirements. For the plastic parts with high surface requirements, plastic materials with low shrinkage should be used as far as possible, and appropriate amount of lubricant can also be added in the raw materials.

     5. The shape and structure design of injection molding products is unreasonable. When designing injection molding product structure, the wall thickness should be as consistent as possible. If the wall thickness difference of injection products is large, it can be solved by adjusting the structural parameters of the pouring system or changing the wall thickness distribution.