Is ultrasonic welding better or hot melt welding better in the production process in automotive wiring harness? What are the advantages and disadvantages of each? Please, prawns. ...

It depends on what material your harness is made of and how pure it is. If it is copper and aluminum, the higher the purity, the better the weldability and the stronger the weldability.

Then, the second point is to see how big the welding area (volume) is. The area is too large, the welding machine requires high power and the cost is of course high.

In terms of benefits, ultrasonic welding, but with small internal resistance, is highly recommended from the perspective of line safety. In addition, the welded terminal can be molded, and the welding efficiency is high enough to kill hot melt. (Of course, this ignores the equipment price, hehe)