heat distribution in spot weldingbesides the

Question

Heat distribution in spot welding

Besides the resistance at the interface, there are six other resistance through which the same welding current is passed. They are:

1. Resistance of the upper electrode - R₁
2. Resistance of the upper electrode metal contact - R₂
3. Resistance of the top metal - R₃
4. Resistance of the bottom metal - R₄
5. Resistance of the metal - bottom electrode contact - R₅
6. Resistance of the bottom electrode -R₆

Therefore, some amount of heat is generated in these regions also (equal to I² x R x t).

The effective heat that is utilised is that due to the resistance at the metal - metal interface only, the others being losses.

Among the above six resistance, R₂ and R₅ are high compared to the other four. These two can be minimised by properly choosing the electrode pressure and cleaning the surface well.