Reasons and solutions for transparent defects in plastic injection molded products

Injection moldMolding technology is a commonly used method of production of plastic products. Many types of plastic products are produced by plastic products factories using injection molding machines. For example, mobile phone cases that are very popular in our lives are one of them, but many Immature technologyInjection Mold FactoryHomeWhen using TPU, PC and other materials to make transparent products, some sparkling silver lines often appear, which greatly affects the aesthetics of the products. So what are the reasons for the quality problems of such transparent injection molded parts?How to solve it?

In fact, the quality defects of transparent products such as melting spots, silver streaks, cracked polystyrene, plexiglass, etc., which are produced by injection molding, are mainly caused by the stress generated in the vertical direction of the tensile stress during the injection molding process. The right-of-use polymer molecules have a heavy flow orientation, which shows the difference in the reduction rate of the unoriented part.

The solutions generally adopted for such problems are as follows:

  • (1) Eliminate the interference of gas and other impurities, and fully dry the plastic.
  • (2) Reduce the material temperature, adjust the temperature of the barrel section by section, and increase the mold temperature appropriately.
  • (3) Increase the injection pressure and reduce the injection speed.
  • (4) Increase or decrease the pre-plastic back pressure and reduce the screw speed.
  • (5) Improve the exhaust condition of the runner and cavity.
  • (6) Clean up possible blockages of the nozzle, runner and gate.
  • (7) Shorten the molding cycle. After demolding, annealing can be used to eliminate silver streaks: for polystyrene, keep at 78°C for 15 minutes, or at 50°C for 1 hour, for polycarbonate, heat to over 160°C for several minutes .

Most of the quality problems in the production process of plastic injection products are caused by process conditions, materials, or maintenance of machines and molds.Therefore, to produce high-quality, high-precision, and high-level plastic products, it is necessary to control the entire production process, from the details to the injection mold, injection molding equipment, the technical experience of the operators, the production environment of the workshop, and the production environment. All aspects of raw materials meet high standards.

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