2.15 - Design for Six Sigma (DFSS)

What Is DFSS?

DfSS is an elaboration of the Deming, Shewhart cycle or more simply the management cycle. See guide 2.17

DFSS is the acronym for Design for Six Sigma — almost every company or training organization will define DFSS differently. A company will implement DFSS to suit their business, industry and culture. Others will implement the version of DFSS used by the consulting company assisting in the deployment. Because of this, DFSS is more of an approach than a defined methodology. As yet, the phases or steps of DFSS are not universally recognized or defined.

DFSS is used to design or re-design a product or service from the ground up. The expected process Sigma level for a DFSS product or service is at least 4.5 (no more than approximately 1 defect per thousand opportunities), but can be 6 Sigma or higher depending the product. Producing such a low defect level from product or service launch means that customer expectations and needs (customer Critical to Quality CTQ) must be completely understood before a design can be completed and implemented.

There are a number of methodologies, all using different acronyms, currently being used to support Design for Six Sigma. Below we compare and contrast them at the phase description level. They are:-

DMAIC, DMAV, DCCDI, IDOV and DMEDI.

DMAIC

One of the most popular Six Sigma methodologies is the DMAIC methodology, because they have existing processes that are wasting resources (hence the big savings you’ve heard about at GE, Honeywell and others over the past years). The remaining Six Sigma practitioners are using a Design for Six Sigma (DFSS) approach to design a new product for Six Sigma quality.

The DMAIC methodology should be used when a product or process is in existence at your company but is not meeting customer specification or is not performing adequately.

The DMAIC methodology is widely defined as comprising the following five phases: Define, Measure, Analyze, Improve and Control. In some businesses, only four phases (Measure, Analyze, Improve and Control) are used; in this case the Define deliverables are considered pre-work for the project or are included within the Measure phase. A variation known as DMAIIC, is sometimes used where the first I stands for Improve and the second I stands for Implement. The DMAIC methodology breaks down as follows:

• Define the project goals and customer (internal and external) requirements.
• Measure the process to determine current performance.
• Analyze and determine the root cause(s) of the defects.
• Improve the process by eliminating defect root causes.
• Control future process performance.

DMADV

One popular Design for Six Sigma methodology is called DMADV, and retains the same number of phases and general approach as DMAIC. The five phases of DMADV are defined as: Define, Measure, Analyze, Design and Verify.

• Define the project goals and customer (internal and external) requirements.
• Measure and determine customer needs and specifications; benchmark competitors and industry.
• Analyze the process options to meet the customer needs.
• Design (detailed) the process to meet the customer needs.
• Verify the design performance and ability to meet customer needs.

A slight modification on the DMADV methodology is DMADOV: Define, Measure, Analyze, Design, Optimize and Verify.

Other versions of DFSS that are of interest are: DCCDI, IDOV and DMEDI.

DCCDI

DCCDI is being popularized, and is defined as Define, Customer Concept, Design and Implement. There are many similarities between these phases and the DMADV phases.

• Define the project goals.
• Customer analysis is completed.
• Concept ideas are developed, reviewed and selected.
• Design is performed to meet the customer and business specifications.
• Implementation is completed to develop and commercialize the product/service.

IDOV

IDOV is a well known design methodology, especially in the manufacturing world. The IDOV acronym is defined as Identify, Design, Optimize and Validate.

• Identify the customer and specifications (CTQs).
• Design translates the customer CTQs into functional requirements and into solution alternatives. A selection process whittles down the list of solutions to the “best” solution.
• Optimize uses advanced statistical tools and modelling to predict and optimize the design and performance.
• Validate makes sure that the design you’ve developed will meet the customer CTQs.

DMEDI

DMEDI is being taught by a major consulting house and stands for Define, Measure, Explore, Develop and Implement. From what has been discussed earlier identifying the main objectives in each of these phases based on the title of each phase is relatively straightforward.

As you can see, the DFSS approach can utilize any of the many possible methodologies. All these DFSS methodologies use the same advanced design tools (Quality Function Deployment, Failure Modes and Effects Analysis, benchmarking, Design of Experiments, simulation, statistical optimization, error proofing, Robust Design, etc.). Each methodology primarily only differs in the name of each phase and the number of phases (and, of course, the acronym).

How do you decide which DFSS methodology to use? If you are using a consulting company to help with your deployment, use their methodology as their training materials will be tailored around it. If you are implementing DFSS on your own, any of the DFSS books available should get you going in the right direction.

In any case, following a detailed DFSS methodology will help you achieve high quality levels for new products and services. If you are interested in improving your existing products or services, you may find the DMAIC approach is the more appropriate methodology to use.

Notes:

This guide was adapted from the www.isixsigma.com “DMAIC vs DFSS” article. DFSS is not a replacement for TQM. In fact the culture changes required for TQM are also the environment required for DFSS to be truly effective. Each of the methodologies described above are tailored adaptations of the basic management cycle – PLAN – DO – REVIEW.

The Management Cycle – Diagram

To design your own methdology see guide 10.07 or get a ready made one from a site like this - www.method123.com.

Also see www.m-t-d.co.uk/blog/management-cycle.htm for other information on the management cycle.