If the welding points of the capacitor energy storage spot welding machine are of good quality, there will be no defects in both appearance and inside the weld core. From an external perspective, the solder joints have a smooth surface without any defects such as burns or deep indentations. From an internal perspective, there should be a weld nugget of appropriate size, which should be a very dense cast structure and free from defects such as shrinkage, porosity, and cracks.

If the welding parts of the capacitor energy storage spot welding machine are not cleaned properly and the selection of standards is improper during spot welding, it can cause defects to occur. The main defects of spot welding are:

1. Incomplete melting:

Not fully melted refers to the absence of a "bean shaped" cast spot welding structure during spot welding. This kind of defect is dangerous. It will greatly reduce the strength of the solder joints. Moreover, such defects are generally not detectable from the appearance. The main reason for incomplete fusion in energy storage spot welding machines is due to insufficient heating of the welding area caused by low welding current density or short welding time. There are various reasons for the decrease in current at the welding site.

For example: ① Inappropriate adjustment of welding process specifications, ② Increased secondary circuit resistance, ③ Partial shunt phenomenon, ④ Decreased network voltage, etc.

2. Splashing:

Splashing appears in the energy storage spot welding machine over time. A small amount of splashing is inevitable, and if the splashing is too large, it will cause the indentation to be too deep. The deep indentation on the work surface can cause a significant decrease in weld nugget strength. There are two types of splashing, namely initial splashing and final splashing. The initial splashing is generated at the moment when the current is closed. The main reason is due to the short pre pressing time, unclean welding surface, and low pressure. The splashing of energy storage spot welding machines occurs at the end of power on, mainly due to the welding current being too high or the welding time being too long. The melted metal in the core is so large that the surrounding plastic ring cannot be covered under electrical pressure, resulting in the overflow of liquid metal.

The method to eliminate splashing is to identify the cause of splashing, adjust the welding specifications appropriately, or improve the surface quality of the workpiece.