What is Roll Welding | Diagram , advantages and application

Roll welding is a solid state welding process in which pressure sufficient to cause coalescence is applied by means of rolls, as shown in Figure 3.20, either with or without external heat. If the welding is done without applying heat, it is called cold roll welding and if the heat is used for welding, it is called hot roll welding. This process is similar to forge welding except the pressure applied by means of rolls rather than by means of hammer blows. Coalescence occurs at the interface between two parts by means of diffusion at the faying surfaces. Parts to be welded should be ductile and free of work hardening. Before the welding is carried out, the surface to be joined should be cleaned. If the parts to be welded are small, the pressure applied by rolls is done by using simple hand operated tools. For heavier sizes of parts, power presses are used to apply pressure.

One of the major uses of this process is the cladding of mild or low-alloy steel with a high-alloy material such as stainless steel. It is also used for making bimetallic materials for the instrument industry.

Advantages of roll welding:
1. Metals such as soft aluminium, copper, gold and silver can be easily welded by roll welding.
2. The operation is easy and it uses simple equipment.
3. There is no need of using flux and filler metal.
4. Environmentally friendly process i.e. no fumes, gases, or smoke generated.
5. It is smooth and clean process.
6. Less time is required.

Limitations:
1. It needs extreme pressure to perform the welding process.
2. The cost of equipment is high.
3. Weld quality is less as compared to fusion welding.
4. It is limited to welding of flat shapes.

Applications of Roll Welding:

1 . It is used in cladding of stainless steel to mild steel for corrosion resistance.
2. It is used in making bimetallic strips.
3. Roll welding is used to produce sandwich strips to convert it into coins.