A technique for welding polymer matrices with low melting temperature, in which the parts are brought into contact with a hot plate. The plate surfaces are

usually coated with polytetrafluorethelyne (PTFE)to keep the parts from sticking to the hot plate. For high- temperature polymeric matrices, special bronze alloys may be used to reduce sticking. In some cases, non-contact welding is used, in which the parts are brought very close to the hot plate without actually touching it. In this case, the hot plate is elevated to very high temperatures and the composite surfaces are heated by convection and radiation. This technique is especially good for mass production of small parts. It is tolerant of variations in material properties and welding conditions and is widely used for welding thermoplastics. This technique is not flexible and is not often used in small production of parts with varying geometries. Because heating and pressing are done at different times, this technique is difficult to use for composites with high thermal conductive reinforcements; the surfaces cool and resolidify before the parts can be aligned and pressed together.

 

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