The size of spark is related to the matching degree of current and voltage. The general matching formula is v =14+0.05a. If the voltage is greater than the matching current, it will pilling, and if the voltage is less than the matching current, it will splash and the spark will be larger.

The solution of big spark:

Resistance spot welding machine, low voltage and high current spot welding. This kind of spot welding machine has the advantages of proper adjustment of spark parameters, good contact and small spark.

The main method is to debug more.