Genichi Taguchi Quality Management Philosophy

Genichi Taguchi Quality Management Philosophy

Taguchi is famous for his pioneering methods of modern quality control and low-cost quality engineering. He is the founder of what has come to be known as the Taguchi method, which seeks to improve product quality at the design stage by integrating quality control into product design, using experiment and statistical analysis. His methods have been said to fundamentally change the philosophy and practice of quality control.

Taguchi methods

Taguchi developed methods for both online (process) and offline (design) quality control. This formed the basis of his approach to total quality control and assurance within a product's development life cycle. His approach emphasised improving the quality of product and process prior to manufacture (that is, at the design stage) rather than the more traditional approach of achieving quality through inspection.

Quality loss function

Taguchi's approach differed from the traditional one of manufacturing a product within a specification based on tolerances equally spaced around a target value. He developed a concept of quality loss occurring as soon as there is a deviation away from the target value, and worked in terms of quality loss rather than just quality. He defined quality loss as 'the loss imparted to society from the time the product is shipped', and this related the loss to society as a whole. Thus, it included both company costs such as reworking, scrapping and maintenance, and any loss to the customer through poor product performance and lowered reliability.

Signal to noise ratio

One of Taguchi's most innovative ideas was to utilise a 'quality' measure called the signal to noise ratio, which was then used by communications engineers to find the strength of an electrical signal. Taguchi applied this measure to everyday products, and used it as a measure to choose control levels that could best cope with changes in operating and environmental conditions, or noise.

Robust quality of design

On the basis of the signal to noise measure, Taguchi was able to develop the concept of robustness, which enables a product to be designed to be less affected by noise. Given normal variations in process operations, the product in question would be less likely to fail acceptable quality criteria.

Invest last not first

Taguchi placed much emphasis on initially optimising the product and process to engineer product quality (parameter design) into the system. Using low cost materials and components was a vital feature of this, and money was spent on higher cost items only when necessary (tolerance design).