Discussion on Loading Moment of Forging Force in Aluminum Alloy Spot Welding

In the author’s opinion, Spot Welding Procedures Chart D.1 (hereafter referred to as Figure D.1) in Appendix D of International Standard ISO 15609-5 [1] is not accurate in principle. This figure is not suitable for materials need exerting forging force for spot welding such as aluminum alloy, especially hard aluminum alloy, for it does not correctively reflect loading moment of forging force. In the author’s opinion, the loading moment of forging force given by Figure D.1 is too late, which will lead to the generation of crack. In addition, two important reasons equally considered to advance loading moment of forging force are: (1) different spot welding equipments have different response time for welding pressure; (2) electric response speed is faster than that of mechanical or pneumatic mechanism, that is to say, response speed of current shall be faster than implementation speed of forging force. Is this paper, we discuss such above-mentioned kinds of different situations. We suggest advancing the forging force in Figure D.1 to the maintenance course of welding current. We propose an amended spot welding course schematic diagram and a simplified schematic diagram.