High-frequency resistance welding

From GAWDAwiki

High-frequency resistance welding is a resistance welding process utilizing currents in the 10,000 – 500,000 Hz range. Base metals coalesce when heat is generated by their resistance to the current passing through them, in addition to an upsetting force which is applied quickly following sufficient heating. The proximity effect is responsible for controlling the path of the current.

Process

A high-frequency current is applied to the metals’ faying surfaces before they are brought together. The current is introduced by applying sliding contacts to the joint edge. The current originates in one contact, then flows down one side of the seam until it reaches the weld point located between the pressure rolls. From the weld point, the current moves up the other side of the seam until it reaches the other contact.

Heat is concentrated at the surface of the metal as the current flows down the edge. When it arrives at the weld point (the area between the rolls), the metal there reaches plastic temperature. Pressure is then applied and coalescence occurs.

Applications

High-frequency resistance welding is commonly used when forming pipes, tubing, structural shapes and other items consisting of long strips of material.^[1]