Types of Resistance Welding

Types of Resistance Welding:(A)Butt welding:

❉ Rods, pipes and wires are welded by this method. As shown in Fig. (A) there is a transformer, across secondary of the transformer two pieces of metal to be welded are held. The two pieces are held in clamps. One clamp is fixed and other is movable

(A) Butt welding

❉ The pieces of pipe are made to touch each other and force/pressure is applied through springs. When supply is given to transformer, current passes through the pieces of pipes and sufficient heat is developed at the joint causing welding at the joint.

(B)Flash butt welding:

❉ This is modification of butt welding. The ends of the pipe to be welded are held together with a little force/pressure applied to them. Arcing at the joint is allowed to take place. This removes any unevenness at the joint. A weld having a fin around the joint is obtained Fig.(B)

(B) Flash butt welding

❉ The fin can be easily removed. Two dissimilar metals can be effectively welded with this method. This welding method is faster than other methods.

(C)Spot welding:

❉ In spot welding, the welding is done at certain points on metallic sheets. The pieces to be welded are held between the two electrodes as shown in Fig.(C)

(C) Spot welding

❉ When current passes through the electrodes a spot weld is produced between the sheets.

(D)Projection welding :

❉ It is a modified form of spot welding. The electrodes used are flat and not pointed as in case of spot welding.

(D) Projection welding :

❉ Projections are made on one sheet so that heat is concentrated in that region. When current is passed through the electrodes. The current density and pressure required is less hence electrode life is more. The welding automatically takes place only at the projections.

(E) Seam welding:

❉ It is similar to sport welding. In seam welding, a series of spots is produced by roller electrodes. As shown in Fig. (E)

(E) Seam welding

❉ Two sheets are passed under the two rolling electrodes. Depending upon the number of welding current pulses are second and speed of electrodes, a series of spot welds is obtained.

(F)Energy storage welding/percussion welding:

❉ Welding is obtained by discharging the stored energy in capacitor. As shown in Fig. (F) it consists of a bridge rectifier, capacitor, switching arrangement.

(F) Energy storage welding

❉ The pieces to be welded one kept at a certain distance apart (1.5 mm). Switch 'S' is put on position 1. So capacitor gets charged through the bridge rectifier.