Resistance Spot Welding – Impact of Process Parameters on Weld Nugget Formation AUTHOR AFFILIATION Mohd Rashidi Asari Department of Manufacturing Engineering (Body) Perusahaan Otomobil Nasional, Perak, Malaysia Email : rashida@proton.com ORCID : 0000-0001-5615-1340 ABSTRACT In automotive manufacturing processes, spot welding is widely used to join body parts to form car body structure. The joint quality of body structure by spot welding is determined by weld nugget’s diameter which directly reflects on shear load requirement by body design. Depending on sheet material’s type and thickness, welding transformer type and material of welding gun electrode tip used, different combination of welding process parameters are required to form desired weld nugget meeting user’s requirement. The real challenge is to get optimized welding parameter’s combination to meet weld quality requirements while reducing utilities consumption and welding consumables. There are many method to get optimized welding parameters. One of them is using Taguchi method to analyze the contribution of each welding parameters – weld force, weld current and weld time towards weld nugget’s formation. However, in this article, graphical weldability lobe is used to show how those welding parameters are interrelated. Keywords Weldability lobe . Lobe curve generator . Welding energy efficiency