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Why do plastic mold injection products produce transparent defects ?

date：2023/08/19

Injection molding technology is a kind of plastic product production method that is widely used nowadays. Many kinds of plastic products are produced by plastic products factory using injection molding machines. One of the mobile phone cases that we like very much in our life is one of them. However, many injection mold manufacturers whose technology is not mature enough often produce some sparkling silver streaks when using TPU, PC and other materials to make transparent products, which makes the products greatly affected in terms of aesthetics, so the quality of such transparent injection molded parts appears. What are the reasons for the problem? How to solve it?
 In fact, the quality defects of silver, scratches and cracks in the injection of transparent products such as melt spots, silver streaks, cracked polystyrene, and plexiglass are mainly due to the stress in the vertical direction of the tensile stress during the injection molding process. The weight of the polymer molecules is expressed by the heavy flow orientation and the difference in the unfolded portion.
 
The general solution to this type of problem is as follows:
 
   (1) Eliminate interference from gases and other impurities, and dry the plastic sufficiently.
   (2) Reduce the temperature of the material, adjust the temperature of the barrel in stages, and appropriately increase the mold temperature.
   (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 flow path and cavity exhaust conditions.
   (6) Clean up possible blockages in the nozzles, runners, and gates.
   (7) Shortening the molding cycle. After demolding, the silver grain can be removed by annealing: hold the polystyrene at 78 ° C for 15 minutes, or 50 ° C for 1 hour, and heat the polycarbonate to 160 ° C for several minutes. .

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