Robust design based on model of product design quality

Nowadays, enterprises continually realize that perfect quality of products is not achieved by manufacturing, but by designing. Therefore, it is necessary to start from the headwaters of quality. That is to say, product quality must be controlled from design phase. Taguchi Method is just the most powerful weapon in improving design quality. In this paper, mainly started from the fluctuation theory, the design model of product quality is put forward. To reduce tolerance and to reach zero defects with great efforts, it is the necessary by implementing robust design. Therefore, the thrice design (system design, parameter design and tolerance design) is just the most way for reaching the above targets. In this paper, the basic concept and principle connected with implementing Thrice Design are profoundly discussed.