Plastics joining infrared

Plastic parts with a thin black layer on one side can be continuously welded in place. For example, if the black layer is one part of a bUayer, coextruded sheet, it could be unroUed and welded in place. The heat needed for welding would be generated precisely where it is needed, minimizing damage to the part and allowing the joining of thin polymer films. Thin films, particularly when coated on a metal, that are hard to join by other methods should he readily and rapidly joined by infrared welding. 

The current application for infrared welding is in the joining of plastic pipes, but it has the potential to be used in many areas where hoq>late welding is currently used, and has been demonstrated on composites. 

Figure 14.25 Pressure vs. time curve showing the three phases of infrared welding. Joint surfaces are heated to the melting temperature of the plastic in phase I Heating Time). In phase II (Change-over), parts are pressed together under pressure. Infrared heaters can be removed in this phase if they are in the way of the parts to be joined. In phase III (Joining and Cooiing), a weld is formed as the hot molten material cools under pressure.

Taylor, N. S., Klaiber, R, and Wermelinger, J., Assessment of PP and PVDF Joints Made by a New Infrared Joining System, ANTEC Conf. Proc., Soc. Plastics Eng., 1993. 

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