Process and dimensional variation analysis of automobile assembly in development phase using Six Sigma DMAIC

The perceived quality of a part/assembly depends on aesthetic and ergonomic aspects and if not given importance in the early phase of manufacturing, then more time for rework is required after the assembling the product to achieve the optimum gap between adjacent trims during the pilot phase of the product. This delays the launch of the product. Thus, present study analyses relative gap between the neighbouring or adjacent trims section to find the causes for defects like increased gap between adjacent trims and process variation causing it and provide an understanding of the assembly variations to operators and engineers. Using a Six Sigma: define, measure, analyse, improve and control (DMAIC) methodology, gap between the trims is analysed, and significant error contributors were identified. After that Monte Carlo simulation is performed. Based on simulation results, major contributors affecting the variations were identified. Further influence of each error contributor was reduced to increase the process capability (Cp). Improvement of about 46.5% is observed in critical trim sections during the development phase of a new vehicle. This eliminated the need for further processing and reworking, which is the reason for the delay in the launch date and provides an understanding about the sections more prone to dimensional variations.