Resistance Welding Basics Explained

Electric resistance welding is the welding of metals with the use of electricity. This occurs when heat is created from the resistance of the current through the working surfaces from the welding process. This heat then melts the metals and melds them together. Small puddles of molten metal form where the electrical resistance is the greatest. There are 2 types of resistance welding: seam welding and spot welding.

Benefits of Resistance Welding

Electrical resistance welding has increased due to its lower pollution output and more efficient methods. The use of resistance welding is indicated in smaller projects with thinner metals. These metals can not withstand high levels of heat and electricity, but resistance welding is less intense. In addition, as less energy is needed, this process helps to lower costs in the workshop and electrical bill.

Downsides of Resistance Welding

Since resistance welding is designed for lighter metals, this process is not effective for heavier sheets of metal. In addition, while the running costs are low, the equipment can be much more expensive than traditional welding materials.

Seam Welding

As the name suggests, this type of welding is used to seal seams in metals. Two electrodes are needed to create current and pressure in order to seal the seams. The electrodes are shaped in a wheel to help make the seams long and continuous, reinforcing them and making them as strong as possible. Often, the process of seam welding can be done with a machine, which makes the results more consistent as well as quicker. Steel and copper piping undergoes resistance welding to create the forms which will then be used in construction projects. Low voltage electrical current is supplied from a transformer and then fed to the electrode with pressure to create the seam.

Spot Welding

Used in smaller projects and for repairs, spot resistance welding can help to join thin sheets of metal. Two electrodes made of copper are used to bring the metal sheets together. Then, electrical current is passed between the electrodes and the metal to weld them together. The heat from this process creates resistance in the metal, which then bonds the sheets together. It's essential that the heat not be applied too quickly or intensely as the heat should remain at the center of the metal and not on the outside.

Other potential types of electrical resistance welding include flash welding, upset welding, and resistance projection welding. Flash welding occurs when two metals are pushed together and then an electrical current is passed between them. The resulting connection point is free of oxides which might weaken the seam. Upset welding takes place when metals are brought to high temperatures and no extra welding materials are added to the point.  Resistance projection welding occurs at studs, nuts, or other raised points.

Resistance welding helps to join metals together with electrical current, creating heat which then leads to finished pieces.