Resistance spot welding of aluminium alloy sheet 5J32 using SCR type and inverter type power supplies

Purpose: A characteristic was compared and analyzed between the lobe diagram of SCR type resistance spot welding and that of inverter type resistance spot welding of the aluminum alloy sheet 5J32 for the car body. Design/methodology/approach: Using the lobe diagram on the electrode force, weld time, and weld current which are process variables of the resistance spot welding, the range of optimal welding condition was determined. The low limit of the range of the optimal welding condition was decided by the lower limit of the tensile strength of the aluminum alloy sheet 5J32, and the upper limit was decided by whether an expulsion occurs or not. Findings: It was found that the range of the optimal welding condition of the inverter type resistance spot welding was larger than the SCR type resistance welding and that the nugget size of inverter type resistance spot welding was larger in the same welding condition. Research limitations/implications: A comparison was between the lobe diagram at the SCR type on the aluminum alloy sheet 5J32 and the lobe diagram at the inverter type resistance spot welding. Practical implications: In this study, by comparing the range of the appropriate welding condition of the resistance spot welding between SCR type and inverter type power supplies, the characteristic of the appropriate welding range by the power supply characteristic could be confirmed. Originality/value: This study compared the characteristic of the resistance spot welding between the SCR type and inverter type power supply using lobe diagram. It was confirmed that the range of appropriate welding conditions of the inverter type resistance spot welding was large.