How to Repair Plastic Injection Molds by Welding

Plastic injection molds, the tools commonly used to manufacture plastic parts, frequently require welding repair. Such repair takes place either during manufacture, due to errors in machining or to changes in the design of the mold, or during service, due to failure in the tool. Typically, fusion welding is for rebuilding worn or cracked surfaces or to modify the shape of existing tools. Fusion welding is also used for routine maintenance, to increase tool life, remove surface wear, and reduce erosion and stress cracking. Laser welding, among fusion welding procedures, provides optimal mechanical properties after welding.

Things You'll Need

  • Laser welding tool
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Instructions

    • 1

      Determine which kind of laser welding is appropriate for your particular welding needs. In contour welding, for instance, the laser is guided along a predetermined welding pattern, and the material only melts where the laser is directed -- allowing extreme localization of welding. In mask welding, a mask is inserted between the two surfaces being welded, the laser beam is moved across the entire joining area of the parts, and the laser only heats the portions not separated by the mask. In contrast, simultaneous welding will heat the entire joining surface.

    • 2

      Turn on the laser beam, and activate pulsing.

    • 3

      Focus the laser beam on the specific area of the materials where you would like the beam to conduct heat. The beam will conduct heat into the joint, converting the solid materials to liquids.

    • 4

      Allow the materials to cool from liquids to solids. When they cool, they will be joined, or welded, at the site where you focused the laser beam.

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