Genichi Taguchi

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Born: Jan 1, 1924

Died: June 2, 2012

Genichi Taguchi is best known For:

KEY Takeaways

  • Taguchi's methodology is based on the idea that quality must go beyond the target values.
  • Robustness is about making sure that the product will work even if there are variations in its environment.
  • There are three stages of product development: system design, parameter design, and tolerance design.


The executive director of the American Supplier Institute, the director of the Japan Industrial Technology Institute, and an honorary professor at Nanjing Institute of Technology in China. Genichi Taguchi is well known for developing a methodology to improve quality and reduce costs, which, in the United States, is referred to as the Taguchi Methods. he also developed the quality loss function.


Mid 50's: Genichi Taguchi was the Indian Statistical Institute's visiting professor, where he met Walter Shewhart.

1960: Genichi Taguchi was awarded the Deming Application prize for his contributions to the field of quality engineering.

1986: Willard F Rockwell Medal by the International Technologies Institute

Taguchi's methodology

Taguchi's methodology is geared toward pushing the concepts of quality and reliability back into the design stage, i.e. before manufacturing.

His method provides an efficient technique for designing product tests before beginning manufacturing.

Taguchi methodology is fundamentally a prototyping technique that enables engineers/ designers to produce a robust design that can survive repetitive manufacturing to deliver the functionality required by the customer.

Taguchi considered design more critical than Quality Control in manufacturing processes. Taguchi methods improve product quality during product development by incorporating quality into the product designs.


Taguchi Loss Function

In the traditional goalpost mentality, a product is considered good or bad, depending on whether or not it is within the specification range (between the lower and upper spec limits, i.e. the goalposts).

This approach makes the specification range more important than the nominal (target) value. But, is the product as good as it can be, or should be, just because it is within specifications? Taguchi says no to this.

Taguchi specified three situations:

  1. Larger the better (for example, process yield);
  2. Smaller the better (for example, emissions, rejection rate); and
  3. On-target, minimum-variation (for example, a mating part dimensions in an assembly).

Robust Design - Taguchi's Three Stages of Product Development:

The philosophy of off-line quality control, designing products and processes so that they are insensitive ("robust") to parameters outside the design engineer's control.

System design stage

The non-statistical stage for engineering, marketing and customer knowledge.

Parameter stage

How should the product perform against defined parameters? The robust solution of cost-effective manufacturing irrespective of the operating parameters.

Tolerance design stage

Tolerance around the desired settings. Finding the balance between manufacturing cost and loss.

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