induction welding
the two main aspects of hf welding are processes and power supplies. each of these can be broken down further into subcategories. processes. the two hf welding processes are hf contact and hf induction. in both processes, the equipment that provides the electrical current is independent from the equipment that supplies the forge pressure. also, both hf methods can employ impeders, which are soft magnetic components located inside the tube that help to focus the weld current in the strip edges.
contact welding description
hf induction welding. in the case of hf induction welding, the weld current is transmitted to the material through a work coil in front of the weld point. the work coil does not contact the tube--the electrical current is induced into the material through magnetic fields that surround the tube. hf induction welding eliminates contact marks and reduces the setup required when changing tube size. it also requires less maintenance than contact welding.
it is estimated that 90 percent of tube mills in north america use hf induction welding.
hf contact welding. hf contact welding transfers weld current to the material through contacts that ride on the strip. the weld power is applied directly to the tube, which makes this process more electrically efficient than hf induction welding. because it is more efficient, it is well-suited to heavy-wall and large-diameter tube production.
power supplies. hf welding machines also are classified by how they generate power. the two types are vacuum tube and solid-state. the vacuum tube type is the traditional power supply.