Resistance Welding is a welding process, in which work pieces are welded due to a combination of a pressure applied to them and a localized heat generated by a high electric current flowing through the contact area of the weld.

Heat produced by the current is sufficient for local melting of the work piece at the contact  point and formation of small weld pool ("nugget”). The molten metal is then solidifies under a pressure and joins the pieces. Time of  the process,values of the pressure and flowing current required for formation of reliable joint, are determined by dimensions of the electrodes and the work piece metal type.

AC electric current (up to 100 000 A) is supplied through copper electrodes connected to the secondary coil of a welding transformer.

The following metals may be welded by Resistance Welding:

1.Low carbon steels - the widest application of Resistance Welding

2.Aluminum alloys

3.Medium carbon steels, high carbon steels and Alloy steels (may be welded, but the weld is brittle)

Advantages of Resistance Welding:

1.High welding rates;

2.Low fumes;

3.Cost effectiveness;

4.Easy automation;

5.No filler materials are required;

6.Low distortions.

Disadvantages of Resistance Welding:

1.High equipment cost;

2.Low strength of discontinuous welds;

3.Thickness of welded sheets is limited - up to 1/4” (6 mm);

Resistance Welding (RW) is used for joining vehicle body parts, fuel ranks, domestic 

radiators, pipes of gas oil and water pipelines, wire ends, turbine blades, railway tracks.

The most popular methods of Resistance Welding are:

Spot Welding

Flash Welding

Butt Welding

Seam Welding