Optimization of spot welding on ferrous alloy (vitroperm) via taguchi method / Nur Elora Sofea Zuraiman

Faculty of Manufacturing and Mechatronic Engineering Technology

Thesis (Master of Science) -- Universiti Malaysia Pahang – 2026

Includes bibliographical references

Spot welding is used to attach two or multiple metal sheet together by pressure and heat from electrical current in order to weld the area. Welding parameters such as weld current, weld time, electrode pressure and bounce time plays a significant role to determine the weld quality on the heat affected zone (HAZ) or welding joint. Poor welding joints result in weak weld strength in the affected HAZ which contribute to increase waste and electrical reject in manufacturing. Nowadays, manufacturing industries preferred to apply spot welding in their application as it is a cost efficient and environmentally friendly for high volume production. Most of studies focused on material thickness more than 0.6mm. There is still insufficient research focus on thin material with thickness <0.1 mm of ferrous alloy as thin material present unique challenges such as excessive heat input, electrode indentation, expulsion and difficulty in nugget formation which are not typically encountered in thicker materials. This study primarily focused on optimizing the welding parameters of 18 μm Vitroperm (VP) 500F TL1 insulated material using the Taguchi method L8 orthogonal array. Two sets of samples were prepared using Winding machine with mechanism of spot welding attached to it. Then, these samples are evaluated using 3D Laser Microscope with 10X magnification to determine the welding hole diameter and crack lengths. Subsequently, peel test is done to evaluate the welding strength of weld joint using Instron tensile machine. It is showed that sample 3, 5 and 8 have optimal welding parameter to proceeded with microstructures of Field Emission Scanning Electron Microscopy (FESEM) and Energy dispersive X-ray spectroscopy (EDX) analysis. Based on the results, parameter from Sample 3 is the optimal welding parameter with 12.35V charging voltage capacitor, 66μs of start pulse width, 72.6μs of inner pulse width and 99μs of end pulse width. Low charging voltage capacitor and increased pulse width for start and end weld displayed minimum result of welding hole diameter and good tensile strength. The surface geometry and element content of Sample 3 is relatively better than Sample 5 and Sample 8. It can be seen the Cu content of Sample 3 is the lowest compared to Sample 5 and 8 due to lower charging voltage capacitor, 12.35V and shorter pulse width of 72.6μs in inner weld position. Longer pulse width can increase the copper content as the time of electrode weld on strip sample is longer which the molten part of electrode CuBe2 will be highly deposited on the sample.