What is impulse welding of thermoplastics?

TWI Frequently asked questions

by Felicity Chipperfield

Impulse welding is a variation of hot bar welding where the heated bar is replaced with a thin Nichrome wire positioned behind a PTFE coating or film. During the heating cycle an electric current is passed along the wire, resulting in rapid heating. At the conclusion of the heating cycle, the current is switched off and the wire cools rapidly due to its low thermal mass. The films being joined remain under pressure for the duration of the cooling cycle. In this way, the parts being welded experience a well-controlled heating and cooling regime, while still being held under pressure.