This is Why Your Products Have a Rough Surface (And How Can You Solve It)


For a mold manufacturer, rough surfaces on their products are an indication of problems on all stages of development of the product. When the first batch of parts of a project has a rough texture is easy to tell that there was a lack of precision in planning for the surface of the molded part.

The cause might be an inconsistency on the measures of materials being used or a missed figure on behalf of the engineering department. The results are mostly visible all the time: glossier areas in parts of the product instead of all of it. In the end, most of the problems lie in the mold: from the way it was created to the way the technician is handling it.

The Following is a list of the possible issues that could be checked by a troubleshooter to fix the roughness problem:

First Source of Issues: The Injection Molding Machine

  • The technician could be working with an insufficient supply of the materials he’s supposed to handle, double-checking the numbers here is pretty important.
  • The material barrel is not properly cleaned when a new batch of products is being made. This problem is related to maintenance and the policies the manufacturer has before starting a production cycle.
  • Residuals of cold melt leakage found at the nozzle. This is another source of problems closely related to the maintenance policies of the company with their machines.

Second Source of Issues: The Mold

  • The vent of the mold is too small, and the runner is too thin. Both problems should have been detected at the prototype phase, but they can be solved by increasing the vent size, or by using a film gate.
  • The surface of the mold cavity feels rough to the touch. The problem could be caused by abusing the mold. If the mold is new, you need to ask the mold manufacturer to polish the cavity surface and check for any leaks.
  • The mold temperature is too low affecting the finished products. This is usually a human mistake. You need to raise the temperature of the mold. If the issues persist, you need to have your machine cheeked.

Third Source of Issues: The Injection Molding Process

  • It’s hard to catch a glimpse of the process at it happens, but you can try a few options to make sure none of these is affecting the performance of the manufacturing process:
  • Try to increase the melting temperature; check the heating zone in the barrel, where the material is placed. Most of the times the lack of uniform temperature, is the cause of roughness, make sure the numbers follow the stages of design as they should.
  • Do the same procedure by increasing the temperature of the nozzle.
  • Finally, try to increase pressure on the injection of materials, as well as the times of injection.
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