The current research study aimed to explore the utility of selected problem-solving tools and techniques in root-cause analysis to demonstrate their practical application. An experimental research design adopting a positivist empirical approach with a deductive strategy was followed to assess the effectiveness of a combined (8D & Six Sigma) problem-solving approach in reducing a high defects rate of a mixer shower assembly line. A novel application of the 8D framework in combination with Six Sigma and other analytical tools was found highly effective in reducing the reject rate from 11.84% to 0.11%. Successful identification of the root cause led to the implementation of permanent corrective action ensuring a long-term stable assembly process. The research study provided a problem-solving framework that was found effective in resolving a complex problem and implementing long-term corrective action in an assembly production line. However, this framework can be used in other industries. The research study provides a solution to a high number of leak rejects in a sub-assembly where "O-seals" are used between mating parts. It also provides analytical tools that were found highly effective during the problem-solving process.
Aiming to reduce flatness (Total Thickness Variation, TTV) defects in the lapping process of the silicon wafer manufacturing, it is crucial to understand and eliminate the root cause(s). Financial losses resulting from TTV defects make the lapping process unsustainable. DMAIC (Define, Measure, Analyse, Improve and Control), which is a Six Sigma methodology, was implemented to improve the quality of the silicon wafer manufacturing process. The study design and the choice of procedures were contingent on customer requirements and customised to ensure maximum satisfaction; which is the underlying principle of the rigorous, statistical technique of Six Sigma. Previously unknown causes of high TTV reject rates were identified, and a massive reduction in the TTV reject rate was achieved (from 4.43% to 0.02%). Also, the lapping process capability (Ppk) increased to 3.87 (beyond the required standard of 1.67), suggesting sustainable long-term stability. Control procedures were also effectively implemented using the techniques of poka yoke and control charts. This paper explores the utility of Six Sigma, a quality management technique, to improve the quality of a process used in the semiconductor industry. The application of the Six Sigma methodology in the current project provides an example of the root cause investigation methodology that can be adopted for similar processes or industries. Some of the statistical tools and techniques were used for the first time in this project, thereby providing new analysis and quality improvement platform for the future. The article offers a deeper understanding of the factors that impact on the silicon wafer flatness in the lapping process. It also highlights the benefits of using a structured problem-solving methodology like Six Sigma.
The research study aims to evaluate the precision of the measurement system using Gauge R&R. An experimental research design adopting a positivist empirical approach with deductive strategy was followed to assess the effectiveness of Crossed Gauge R&R technique for validating a measurement system using destructive testing. Crossed Gauge R&R technique in Minitab was found to be highly effective in quantifying different components of measurement variation relative to process variation. Clue generation from the Crossed Gauge R&R study combined with manufacturing and measurement process know-how helped in identifying and eliminating the root causes for measurement variation. Overall Crossed Gauge R&R proved successful in validating the burst strength test equipment. However, it should be noted that manufacturing and test equipment played an equally important part in developing and executing the gauge R&R study and accurately analysing the results. So, Crossed Gauge R&R should be used as an aid rather than the solution for measurement system validation.