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How to remove mold dents​?

Update:24-09-2021
Summary:

1. Causes of dents 1-1 The thickness of each part of th […]

1. Causes of dents

1-1 The thickness of each part of the product is different

1-2 Insufficient pressure inside the Motorcycle Injection Molding

1-3 Insufficient mold cooling

1-4 Deformation due to insufficient cooling time

 

2. Related knowledge

2-1 In the process of producing products, dents occur more frequently in the uncomfortable phenomenon. The plastic injected into the mold shrinks in volume when it becomes cold. Part of the surface hardens first, and bubbles are generated inside. The so-called dents are The slow cooling part produces a conspicuous concave surface in the direction of the bubble shrinkage.

2-2 Materials with large shrinkage are also prone to dents. The setting conditions should be set in the direction of smaller shrinkage. That is, the mold temperature and barrel temperature decrease, and the injection pressure increases, but it should be noted that this may cause residual internal stress.

2-3 Because the dents are better to be inconspicuous, if they do not affect the appearance, they are deliberately processed into corroded patterns on the mold, such as grains, grains, etc. Also, if the molding material is HIPS, it is also useful to lower the mold temperature to reduce the finish. However, once dents occur in these methods, it is difficult to repair polished products.

3, the solution

3-1 Instant: Increase the injection pressure, extend the injection holding time, reduce the barrel temperature and mold temperature, and force it to cool down where the dents are generated.

3-2 Short-term: make up where the dent is generated. When the material in the place where the dent is generated has a narrow place through the edge, make this part thick.

3-3 Long-term: The difference in the thickness of the designed product should be avoided. Reinforcing ribs that are prone to dents, the long and narrow shape should be as short as possible

 

4, the difference in materials

4-1 Materials with large molding shrinkage have large dents. For example, PE, PP, even if only a slight reinforcement ribs, will produce dents.

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