Evolution of LAMP joining to dissimilar metal welding

In recent years, transport machines such as automobiles and aircrafts need to be lightened from the environmental viewpoint, because the weight saving connects to saving energy and emission of greenhouse effect gas or air pollutant. In order to achieve this, dissimilar metals joining utilizing light weight metals is promising. However, in direct joining of dissimilar metals such as aluminum alloy and steel, brittle intermetallic compounds are formed between them, and dissimilar metal corrosion or bimetal (electrical) corrosion is likely to occur easily. In this research, therefore, in order to solve the above problems, LAMP (Laser Assisted Metal and Plastic) joining method, which needs neither parts nor tools such as adhesive, bolts and rivets, was applied to join dissimilar metal plates sandwiching a plastic plate as an insulant. In the previous researches, it was found that the LAMP joining method could produce strong joints between various metals and plastics. For example, Type 304 stainless steel and amorphous polyamide (PA) or polyethylene terephthalate (PET) plastic joint samples of 30 mm width possessed tensile shear loads of more than 3,000 N, where the fracture occurred in the base plastic sheets. In this study, it was confirmed that the method could produce very strong joints between plastics and aluminum alloy or low carbon steel. Consequently, this method could produce the joints of about 5000 N tensile load between low carbon steel and aluminum alloy with PET sheet.