Resistance welding

Today we will see some interesting issues about the resistance welding, a thermoelectric process developed in the last decades of the Nineteenth Century, widely used in the manufacture of metal sheets and wires. Let’s see some data about this type of welding.

Elihu Thomson

The first patents of the sector arose thanks to Elihu Thomson, in 1885, who also produced other advances during the following 15 years. In 1909, he was awarded the Edison IEEE Medal, a very high-level award, for a career in science and/or engineering achievement by the the American Institute of Electrical Engineers.

What is resistance welding?

Resistance welding is a thermoelectric manufacturing process. This is an autogenous welding, since no input material is involved. It is a process widely used in the industry for the manufacture of metallic sheets and wires, in which the metals achieve a heating when reaching the forging or melting temperature, due to their resistance to the flow of an electric current. That is to say, heat is generated by the passage of an electric current through the parts, in the area of attachment of the parts to be joined, for a precise time and with a controlled pressure.

Basic elements of resistance welding

The basic elements in this type of welding that fits very well to automation are:

  • the electrodes where electrical energy flows;
  • the material to be welded;
  • and a pressure on the area to be welded.


Types of resistance welding

There are several types of resistance welding. The main ones are:

  • Spot welding.
  • Welding projections or projections.
  • Welding seam.
  • Butt welding.
  • Spark welding.
  • Insulated wire welding.



Some of the most outstanding advantages of resistance welding are the following:

  • Very short process time.
  • Does not require consumables (such as materials or welding rods).
  • Safe operation due to low voltage.
  • It is a clean and environmentally friendly process.
  • The result is a reliable electro-mechanical connection.


Joule Effect

Resistance welding is based on the Joule effect: heating takes place by passing an electric current through the joining of the parts. The heat released is given by this expression:

Q = 0,24 x I2 x R x. t


  • Q = heat (in calories).
  • I = current of electric current (in amperes).
  • R = resistance (in ohms) to the passage of the electric current.
  • t = time (in seconds).


Some used sources of information: