In many applications involving copper materials, especially in the welding of automotive electronic components, we frequently employ tungsten, molybdenum, and tungsten-copper electrodes. When electrodes are ground or replaced with new ones, even with the same welding current, welding time, and pressure, the heat energy generated appears to be significantly lower. It takes dozens of welds for the heat energy to stabilize.

This primarily occurs because the electrode surface oxidizes after numerous welds, increasing the electrical resistance of the tungsten electrode. According to Q=I²RT, this results in a noticeable increase in heat energy.

There are two methods to resolve the issue of inconsistent energy levels when spot welding with freshly ground or new electrodes:

1. Perform several ineffective discharges to achieve pre-oxidation. This can be achieved by discharging with scrap material several times before welding the actual product.

2. Utilize the “step-up control (step-down control)” function inherent in the “welding power controller.” In the first phase, set 100% current and weld for N cycles. In the subsequent phase, set 90% current and weld for N cycles. After reaching N cycles, you can choose to terminate or continue welding with 90% current. To reset after electrode replacement or grinding, press the reset button, and the current will begin cycling from the first phase with 100% current.

3. For products with longer welding times and significant deformation, while keeping the current constant, you can use the function of reaching a set displacement for immediate power cutoff. When the displacement reaches the preset value, the discharge will immediately cease.