Time Variation Reduction in TIG Welding for Producing Ice Bin ASSY by Applying Lean Six Sigma Concept: A Case Study of Sheet Metal APU, Safran Cabin Lamphun Company Limited

Abstract

The objectives of this research were to reduce the time variation and waste rate of tungsten inert gas (TIG) in the welding processes in the production of Ice bin ASSY, an ice container used in airplanes. This research applied the Lean Six Sigma concept steps of Define, Measure, Analyze, Improve, and Control. Based on the first step, defining with inquiry, and collecting data from the production process, it was found that TIG welding processes were a bottleneck. In the next measurement step, three causes were found using a histogram, a current state value stream mapping, and a Pareto chart, which comprised of linear dimension off-specification, poor welding, and product surface deformation. Then a fishbone diagram and risk assessment were applied to analyze the root causes and rank appearing risks. Based on the analyzation step, it was seen that heat fusion deformed products. Moreover, no working standard and waste of time in assembly of clamping tools appeared in this step. Therefore, with the ECRS principle, a new type of workpiece clamping tool was invented. The future value stream mapping was proposed in the improvement step. The final step was to control and follow up by using work instructions. It was found that time variances were reduced by sixty-five percent and the waste rate decreased by twenty-eight percent.