Hot Gas Welding of Plastic:Fundamentals & Importance

This paper provides an introduction to welding fundamentals in the field of plastic welding to assist in the future developments in this field. In many industry fields plastic part are frequently used. Very demanding criteria must now be fulfilled by parts made of polymeric materials and polymeric composites. Plastics have excellent strength to weight ratio, good corrosion resistance and ability to take good finish. Plastics can be categorized as thermosets and thermoplastics. Among these two only the thermoplastic is weldable. In case of thermosets resin, a chemical reaction occurs during processing and curing, that is, as a result of irreversible cross-linking reaction in the mold. Both molded thermosets and vulcanized elastomer components cannot be reshaped by means of heating, because of the irreversible reaction that occurs. So in this case joining can be obtained by adhesive bonding and mechanical fastening only. Few selected welding process are discussed in this paper like friction welding, hot plate welding, hot gas welding etc. Various important P.V.C. plastics welding parameters such as welding techniques in common use by hot gas welding, equipments requirement have also been discussed.