Welding of Plastics

a process for the permanent joining of thermoplastics and thermosetting plastics in which the separation boundary between the parts being joined disappears. Thermoplastics are welded by means of heat supplied from external sources, such as gaseous heat carriers, heated filler material, or heated tools, or by means of heat generated within the plastic by conversion of various kinds of energy, such as friction, high-frequency currents, ultrasound, or infrared radiation.

Techniques based on a chemical interaction—either a direct interaction between surfaces or an interaction with a filler material—are used in joining thermosetting plastics. This method requires intensive heating of the surfaces and increased vibration of the molecular links in the polymer, either by high-frequency currents or by ultrasound. The welding of plastics, for example, film and sheet materials, is now being introduced in various areas of industry and construction.