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Causes of dents in plastic moulds

news2019-12-07

During the injection moulding process of plastic frames, some unfortunate situations will occur, such as top white, shrinkage, dents. Then how to solve this situation, you need to analyze the cause of the bad, and then solve it Bad phenomenon.

I. Dent

The causes of dents during injection moulding are:

  1. Insufficient mould cooling, short cooling time will cause severe deformation.
  2. This situation also occurs when the internal pressure of the mould is insufficient.
  3. The thickness of each part of the product is different. In this case, the overall treatment method: reduce the barrel temperature and mould temperature, force cooling in the place where the dents are generated, make up the side of the cuts, and control the difference in thickness of the designed product.

4, too crowded places will sag due to considerable shrinkage. Treatment method: By increasing the pressure and increasing the holding time, the depression can be reduced or even eliminated. The key depends on the degree of depression and the manufacturer’s willingness (excessive holding pressure will reduce productivity).

In summary, the leading solutions to the dents generated during the injection moulding of plastic moulds are as follows:

  1. Increase injection energy: pressure, speed, time and material volume, and increase back pressure to make filling mold full.
  2. Increase the material temperature and flow smoothly. Lower the material temperature to reduce shrinkage, and increase the mold temperature appropriately, especially the local mold temperature at the location where the vacuum bubble is formed.
  3. Set the gate on the thick part of the part to improve the flow conditions of the nozzle, runner, and entrance, and reduce the consumption of pressing services.
  4. Improve the mould exhaust condition.

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