How to Modify Mold Cavity Dimensions?

If the produced product dimensions deviate, it means there is an issue with the mold cavity dimensions.

Once the mold cavity dimensions are set, modifying them again can be quite challenging.

But don’t worry, we’ve got some ways. And in this post, we will explain how to modify mold cavity dimensions after finding the deviation of product dimensions.

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In terms of ease of work, it is generally easier to perform ‘welding’ and ‘polishing’ on the moving mold rather than the fixed mold.

Since the quality of the fixed mold’s cavity surface directly affects the appearance of the plastic parts, and there is a significant amount of heat generated during the welding process.

Without adequate process measures to ensure this, the heat often leads to alterations in the composition of the cavity surface, resulting in varying hardness on the cavity surface, which in turn affects the appearance of the plastic parts.

In practice, it’s best to avoid modifying the fixed mold cavity surface.

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Ways to modify the mold cavity

The general steps for modifying the moving mold cavity surface are as follows:

(1) Use the adhesive method to test the mold on the cavity surface and roughly determine the thickness that needs to be added or removed.

(2) Perform ‘welding’ and ‘polishing’ operations.

(3) Test the mold again and adjust the dimensions of the cavity surface based on the molding results.

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The second step is the challenging and critical part, here is a detailed process for repairing the cavity surface:

① Select welding materials that match the base material and determine the welding area. Reserve and protect the polishing reference.

 Build up the material in alternate sections, avoiding continuous welding from start to finish to prevent internal stress from damaging the mold cavity surface.

 Use the reference points and begin polishing, taking care to protect the surrounding areas.

④ Measure the height of the built-up surface, and once it meets the requirements, fill the reference gap to complete the modification of the cavity surface.

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