Design of experiments (DOE) is a crucial tool in Six Sigma quality management and its application is widespread in Japan; nevertheless, many manufacturing companies in other countries have not formally adopted it because of its complex concepts and costs. As a matter of fact, the essence of the DOE method lies in optimizing the parameters of engineering design and mass production. This article features a case study of reducing tire leakage rate with DOE method.

Terminology

DOE is a statistically organized method that is implemented by altering (changing the levels) inputs (factors) and then observing the output (the interaction effects among various factors and the response of specific quality characteristics); that is, y=f(x) where x stands for input and y stands for output. The philosophy of the DOE approach originates from British mathematician R.A. Fisher in the early 20th century.

Full factorial design (FFD), also called a fully-crossed design, measures the effect of each factor on a response variable. That is to say, all possible combinations of levels and factors are treated.

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