Six Sigma at many organizations simply means a measure of quality that strives for near perfection. It is a disciplined data-driven approach and methodology for eliminating defects in any process, from manufacturing to transaction and from product to service. This paper demonstrates the empirical application of Six Sigma and DMAIC to reduce product scrap within a piston manufacturing organization. The paper follows the DMAIC methodology to investigate defects and root causes, and provides a solution to reduce/eliminate these defects. The analysis employing Six Sigma and DMAIC indicates that the design of casting spoon and its material influence the amount of defective pistons produced. In particular, the why-why analysis and two sample t-Test are combined to statistically determine the correlation of the casting spoon design and its material with defects as well as to define their optimum values needed to reduce/eliminate the defects. As a result, a reduction of scrap percentage from 9.9% to 5% was achieved, which helped the studied organization to reduce its Defects Per Million Opportunities (DPMO) from 99,000 to 50,000 and thus improve its Sigma level from 2.86 to 3.2. Also, the process yield was improved from 90.1% to 95% and a saving of 52 lakh/year was obtained.

In today’s world, business has become highly competitive. All industries and organizations have to perform well in order to survive and be profitable. The piston manufacturing industry (the organization studied in this paper) as well has to maintain the quality of its products so as to be able to delight customers and thus effectively compete in the market. In general, one of the most vital concerns for the piston manufacturing industry is the reduction of common quality defects such as shrinkage porosity and blow hole on skirt and ring zone. From this point, not only does an organization waste its resources and time to remanufacture the products, but it also contributes to the loss of customer satisfaction and trust. As a result, this has driven a particular piston manufacturing organization (anonymity has been maintained) to improve the quality of its products in order to create a competitive strategic advantage for its business and become a global organization for further prospects. This paper investigates quality issues at this piston manufacturing company and provides a solution to reduce/eliminate the most common defects using Six Sigma methodology. As an initial step, the paper briefly reviews some of the relevant theory of Six Sigma and DMAIC, paying particular attention to the benefits and the positive impact on performance that these approaches bring to organizations, and the manufacturing process studied.

Operations Management Journal, Scrap Reduction, Piston Manufacturing Industry, Six Sigma, Defects Per Million Opportunities (DPMO), Voice of the Customer (VOC), DMAIC Methodology.