This study has been made in order to obtain the basic guide for MIG spot welding of commercial aluminum alloys. In this study the effects of welding parameters such as welding current, arc voltage and arc time on MIG spot welds were investigated together with argon gas flow rate and after flow time. And the welding parameter guide for various sheet thicknesses was also chosen. To lower variations in strengths of MIG spot welds the use of a mechanized torch which is regarded as a kind of pull

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... e torches was more effective than that of an oreinary push type semi-auttomatic torch. Therefore, it is found to be more desirable to use a pull type torch for MIG spot welding of aluminum alloys. Tensile shear strengths of MIG spot welds are reasonably high comparing with those of resistance spot welds required by U.S. Military Spec. MIL-W-6858 A. But some alloys such as 6061 and 5052 are seemed to be more susceptible to weld cracking than 1100, 3003 and N 5/6 alloys. Further systematic studies on the weld cracking in MIG spot welding should be necessary to make consistently crack-free welds.