Hi guys. As a mechanical engineering final year student, I was assigned to design and build a cold welding prototype to weld just two sheets of metal together by lap joint. Before I actually start the designing process, I tried to cold weld the two sheet metals together by using simple methods ie, knocking a punch with a hammer to the metals, pressing using a bench vise etc. None of it would join the two together. I used different kinds of materials and thickness (Copper & Aluminium sheet with 0.5mm, 0.8mm and 1.0mm) but all failed. I don't know what is my mistake here. Can anyone help? Thanks in advance.