Abstract

One of the major objectives of a Six Sigma program is to make defect-free, reliable products. Rightfully, customers expect more reliable products from companies adopting a Six Sigma approach. However, many companies implementing Six Sigma are unable to achieve this objective, and the impact of unreliable products can be multifold. The worst effect is reduced customer preference toward a company's product due to loss of confidence. Affected companies also can lose market share and can experience significant adverse impacts on reputation. While manufacture and sale of unreliable products could arise from poor execution of Six Sigma or other similar improvement approaches, it could also result from a lack of understanding of both reliability metrics and the toolset. Moreover, most companies prioritize Six Sigma projects based on cost and profit impacts on business. Unfortunately, the complete cost of poor reliability and durability does not get captured. As a result, reliability and durability improvement projects are frequently designated as low priority at companies.

The Six Sigma Body of Knowledge (SSBOK) for Black Belts in most companies usually does not include life data analysis and other reliability tools. SSBOK does include other tools, such as SPC, MSA, FMEA, Design of Experiments, Hypothesis Tests, ANOVA, and so forth, but, as we know, what we do not measure we cannot improve! Most of the Six Sigma books also do not include reliability tools. Conventional procedures for assessing baseline performance do not include establishment of a reliability requirement. Also, the normal distribution rarely applies to reliability data! Life data contains failure and survival points, which makes analysis more complicated. Under these circumstances, improvement project leaders need to learn and master a set of reliability tools. We call this modified approach ‘Reliability Focused Six Sigma’ (RFSS). In this paper, we will share two case studies to illustrate the RFSS approach. These case studies are based on the personal experience of the authors, and company names and more details cannot be disclosed.