Page 37 - Design for Six Sigma a Roadmap for Product Development

Quality Concepts 15

way that mistakes are impossible to make or at least are easily
detected and corrected.
Poka-yoke devices fall into two major categories: prevention and detec-
tion.A prevention device affects the process in such a way that it is impos-
sible to make a mistake. A detection device signals the user when a
mistake has been made, so that the user can quickly correct the problem.
Poka-yoke was developed by Shigeo Shingo, a Japanese quality
expert. He is credited for his great contribution for tremendous
Japanese productivity improvement.

1.3.7 Robust engineering/Taguchi method
(1960s in Japan, 1980s in the West)
Dr. Genich Taguchi and his system of quality engineering is one of the
most important milestones in the development of quality methods.
Taguchi method, together with QFD, extended the quality assurance
activities to the earlier stages of the product life cycle. Taguchi’s qual-
ity engineering is also called the robust design method, which has the
following distinctive features:

1. Focus on the earlier stages of product life cycle, which include con-
cept design, product design, and manufacturing process design, and
preparation. More recently, Taguchi and his colleagues have extend-
ed that to the technology development stage, which is even earlier
than the impetus/ideation stage. He thinks that the earlier involve-
ments in the product development cycle can produce a bigger
impact and better results and avoid costly engineering rework and
firefighting measures.
2. Focus on the design of the engineering system which is able to deliv-
er its intended functions with robustness. Robustness means insen-
sitivity to variations caused by noise factors, which may include
environmental factors, user conditions, and manufacturing distur-
bances. He pointed out an important fact that variation can be
reduced by good design.
3. Promote the use of Taguchi’s system of experimental design.

1.3.8 Quality function deployment (QFD)
(1960 in Japan, 1980s in the West))
Quality function deployment (QFD) is an effective quality tool in the
early design stage. It is a structured approach to defining customer
needs or requirements and translating them into specific plans to pro-
duce products to meet those needs. The “voice of the customer” is the
term used to describe these stated and unstated customer needs or