DESIGN FOR SIX SIGMA AND THE SIX SIGMA PHILOSOPHY


The six sigma philosophy is becoming more and more popular in the quality field, especially with companies in the electronics industry (de Treville et al., 1995). Organizations striving to attain the quality levels required with the six sigma system usually adopt the following three recommended strategies for accomplishing this goal (Tomas (1991) offers a six-step approach). Improving an existing process to the six sigma level of quality would be very difficult, if not impossible . That is why Fan (1990) insists this type of thinking must already be incorporated into the original design of new products and the processes that will manufacture them if there is to be any chance of achieving six sigma quality.

The three recommended strategies are as follows :

DESIGN PHASE

  1. Design in ±6 ƒ tolerances for all critical product and process parameters. For additional information on this topic, read Six Sigma Mechanical Design Tolerancing by Harry and Stewart (1988).

  2. Develop designs robust to unexpected changes in both manufacturing and customer environments (see Harry and Lawson, 1992).

  3. Minimize part count and number of processing steps.

  4. Standardize parts and processes.

Knowing the process capability of current manufacturing operations will greatly aid designers in accomplishing this first step. And of course, good designs will positively influence the capability of future processes.

Once a new product is released for production, the designed-in quality levels must be maintained , and even improved upon, by working to reduce (or eliminate) both assignable and common causes of process variation. McFadden (1993) lists several additional key components of a six sigma quality program specifically targeted at manufacturing.

INTERNAL MANUFACTURING

  1. Standardize manufacturing practices.

  2. Audit the manufacturing system. Pena (1990) provides a detailed audit checklist for this purpose.

  3. Use SPC to control, identify, and eliminate causes of variation in the manufacturing process. Mader et al. (1993) have written a book entitled Process Control Methods to help with this step. The reader may also review Volume IV of this series.

  4. Measure process capability and compare to goals. Koons' (1992) and Bothe's (1997) books on capability indices are useful here.

  5. Consider the effects of random sampling variation on all six sigma estimates and apply the proper confidence bounds. The reference by Tavormina and Buckley (1992) would be helpful here.

  6. Kelly and Seymour (1993), Bothe (1993), and Delott and Gupta (1990) reveal how the application of statistical techniques helped achieve six sigma quality levels for copper plating ceramic substrates. Harry (1994) provides several examples of applying design of experiments to improve quality in the electronics industry.

A special warning here is appropriate. Even if the first two strategies are adopted, a company will never achieve six sigma quality unless it has the full cooperation and participation of all its suppliers.

EXTERNAL MANUFACTURING

  1. Qualify suppliers.

  2. Minimize the number of suppliers.

  3. Develop long- term partnerships with remaining suppliers.

  4. Require documented process control plans.

  5. Insist on continuous process improvement.

Craig (1993) shows how Dupont Connector Systems utilized this set of strategies to introduce new products into the data processing and telecommunications industries. Noguera (1992) discusses how the six sigma doctrine applies to chip connection technology in electronics manufacturing, while Fontenot et al. (1994) explain how these six sigma principles pertain to improving customer service. Daskalantonakis et al. (1990 “1991) describe how software measurement technology can identify areas of improvement and help track progress toward attaining six sigma quality in software development.

As all these authors conclude, the rewards for achieving the six sigma quality goals are shorter cycle times, shorter lead times, reduced costs, higher yields, improved product reliability, increased profitability, and most important of all, highly satisfied customers.

We have reviewed the principles of six sigma here to make sure the reader understands the ramifications of poor quality and the significance of implementing the six sigma philosophy. In Volume I of this series, we discussed this philosophy in much more detail. However, it is imperative to summarize some of the inherent advantages, as follows:

  1. As quality improves to the six sigma level, profits will follow with a margin of about 8% higher prices.

  2. The difference between a six sigma company and a non-six sigma company is that the six sigma company is three times more profitable. Most of that profitability is through elimination of variability ” waste.

  3. Companies with improved quality gain market share continuously at the expense of companies that do not improve.

The focus of all these great results is in the manufacturing. However, most of the cost reduction is not in manufacturing. We know from many studies and the experience of management consultants that about 80% of quality problems are actually designed into the product without any conscious attempt to do so. We also know that about 70% of a product's cost is determined by its design.

Yet, most of the "hoopla" about six sigma in the last several years has been about the DMAIC model. To be sure, in the absence of anything else, the DMAIC model is great . But it still focuses on after-the-fact problems, issues, and concerns. As we keep on fixing problems, we continually generate problems to be fixed. That is why Stamatis (2000) and Tavormina and Buckley (1994) and the first volume of this series proclaimed that six sigma is not any different from any other tool already in the tool box of the practitioner. We still believe that, but with a major caveat.

The benefit of the six sigma philosophy and its application is in the design phase of the product or service. It is unconscionable to think that in this day and age there are organizations that allow their people to chase their tails and give accolades to so many for fixing problems. Never mind that the problems they are fixing are repeatable problems. It is an abomination to think that the more we talk about quality, the more it seems that we regress. We believe that a certification program will do its magic when in fact nothing will lead to real improvement unless we focus on the design.

This volume is dedicated to the Design for Six Sigma, and we are going to talk about some of the most essential tools for improvement in "real" terms. Specifically, we are going to focus on resource efficiency, robust designs, and production of products and services that are directly correlated with customer needs, wants, and expectations.




Six Sigma and Beyond. Design for Six Sigma (Vol. 6)
Six Sigma and Beyond: Design for Six Sigma, Volume VI
ISBN: 1574443151
EAN: 2147483647
Year: 2003
Pages: 235

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