DFSS - Design for Six Sigma Explained

In 1986, Bill Smith from Motorola found Six Sigma, which is a quality improvement methodology for business processes. The two common methodologies of Six Sigma are DMAIC (Define – Measure – Analyze – Improve – Control) and DMADV (Define – Measure – Analyze – Design – Verify). Among these, DMADV is also known as DFSS or “Design for Six Sigma.” Most of the practitioners of Six Sigma commonly follow the first approach, i.e., DMAIC (examples are General Electric and Honey well). While DMAIC improves the existing process for eliminating the errors, DFSS deals with the generation of new processes and services.

Six Sigma methodologies focus on eliminating all the errors in the manufacturing and service processes, taking the project to almost an error-free level. In short term, if the process operates with Six Sigma, then in the long term, the defects levels will be below 3.4 Defects per Million Opportunities (DPMO). Therefore, the level of quality is very high. In DFSS, customer dissatisfaction is considered to be a grave error that hampers the quality of business processes.

In contrast to the DMAIC methodology, the steps in DFSS are not predefined. Each organization or company defines its DFSS uniquely. Customer satisfaction is of utmost priority in DFSS because in order to generate a product or service whose expected Sigma level is at least 4.5 Sigma, the needs of the customers (CTOs) must be completely studied and understood before product design.

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We can state that DFSS has an engineering background because it involves the generation of new processes and products in contrast to DMAIC, where the existing processes are improved to meet the needs of the customer. The five phases of DMADV (or DFSS) are as follows:

Define design or project goals that meet the demands of the customer through voice of the customer (VOC), analysis (external requirements) and business needs (internal requirements).

Measure and identify factors that are Critical To Quality (CTQs), customer needs, potential competitors and risks.

Analyze the design of the process in order to re-design it for meeting the customer needs.

Design the process in such a way that it meets the customer requirements.

Verify the design performance and if the customers' needs are met through the design.

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In short, DFSS explores the engineering aspects of the process to be designed; hence, the customer finds a significant increase in the product or service efficiency. In order to attain this, DFSS employs specialized tools such as quality function deployment (QFD), design of experiments (DOE), TRIZ, Taguchi methods, and Robustification, unlike those used in DMAIC.

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