Six Sigma application in the aerospace and aviation industry: A case study

Abstract

This study examines the application of the Six Sigma Define–Measure–Analyze–Improve–Control (DMAIC) methodology to reduce weld seam and internal structural defects in titanium tube welding within the aerospace and aviation industry. A case study approach was conducted in an aerospace manufacturing company producing titanium tubes for original equipment manufacturers under strict quality and regulatory requirements. The study integrated attribute measurement system analysis, statistical process control, analysis of variance, and Taguchi design of experiments within the DMAIC framework to identify and optimize critical welding parameters under real production conditions. An L27 orthogonal array was used to evaluate 11 welding process factors while minimizing the number of experimental trials required in a high-cost production environment. The results demonstrated that the process sigma level improved from 1.19 to 2.38, while defects per million opportunities decreased by 69.1%. Significant factors affecting welding nonconformances included low pulse amperage, electrode distance, backing gas flow rate, and machine type. The optimized process reduced rework and scrap, generated approximately $350,000 in financial savings, and improved process stability and operational performance. The study contributes to the quality literature by demonstrating how Six Sigma can function as an integrated quality management mechanism for statistically grounded improvement in regulated, safety-critical manufacturing environments.