Introduction to quality and reliability engineering

This chapter discusses the designer's job—that is, to capture customer expectations and translate as many of these expectations as possible to the final product. To improve business performance, manufacturing companies need to reduce the levels of non-conformance and attendant failure costs, stemming from poor product design and development. High levels of failure cost can produce a loss on sales and can probably reflect the project's failure to recover its initial level of investment. It has been realized for many years that waiting, until the product is at the end of the production line to measure its quality, is not a good business practice. The focus on quality improvement in design is not misplaced. Studies have estimated that the majority of all problems, related to cost and quality, are created in product development. The most significant cost savings can result from changes in product design rather than from changes in production methods. Design is recognized as a major determinant of quality and cost. It is also a driving factor in determining the “time to market” of products. Each product is derived from individual pieces of material, individual components, and individual assembly processes. The properties of these individual elements have a probability of deviating from the ideal or target value. Variation is an obvious measure for quality of conformance, but it must be associated with the requirements that are set by the specification to be of value at the design stage. In many cases, the failures are often costs that are logged as “overheads.”