Hot-gas welding, vibration welding, ultrasonic welding, induction welding and dielectric welding are all methods of plastic welding. Each method has practical applications.
Plastics are softened and joined when a thermoplastic rod is heated along with the plastics in hot-gas welding. Friction heats and joins two plastics when one plastic is vibrated against the other in vibration welding. In ultrasonic welding, two plastics are joined and vibrated by pulses; the vibration heats the plastics, and they are welded together. Two plastics are placed together around a metallic object in induction welding. The metal is heated when it passes through magnetic fields, causing the plastics to weld together. Plastics are welded together when they are joined and broken down under high frequencies in dielectric welding.
Hot-gas welding is typically employed on sheet stock to fabricate large structural parts. Ultrasonic welding is used to weld dissimilar plastics together. Induction welding is often employed to bond difficult-to-weld plastics. Welding thin plastics typically calls for dielectric welding. Vibration welding is used when other methods of welding are impractical.