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


  • Jirapat Wanitwattanakosol -
  • Tulsaporn Manokul
  • Sunutta Wanchaem


Tig Welding, Lean, Six Sigma


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.


Antony, J., Snee, R., and Hoerl, R. (2017). Lean Six Sigma: yesterday, today and tomorrow. International Journal of Quality & Reliability Management, vol. 34(7), 1073-1093.

George, M.L., Maxey, J., Rowlands, D.T., and Upton, M. (2004). Lean six sigma pocket toolbook. McGraw-Hill Professional Publishing.

Sao, S., Chanwiang, W., Dondee, S., and Budsaereechai, S. (2021). Reduction of bubble defect and production leveling: Case study of a hard disk drive company, Industry Technology Lampang Rajabhat University, 14(2), 12-24. (in Thai)

Shokri, A. (2017). Quantitative analysis of Six Sigma, Lean and Lean Six Sigma research publications in last two decades. International Journal of Quality & Reliability Management, 34(5), 598-625.

Singh, M., and Rathi, R. (2019). A structured review of Lean Six Sigma in various industrial sectors. International Journal of Lean Six Sigma, 10(2), 622-664.

Stamatis, D.H. (2019). Six Sigma fundamentals: A complete introduction to the system, methods, and tools. New York: CRC Press.

Suhardi, B., Anisa, N., and Laksono, P. W. (2019). Minimizing waste using lean manufacturing and ECRS principle in Indonesian furniture industry. Cogent Engineering, 6(1). https://doi.org/10.1080/23311916.2019.1567019.