Design for Six Sigma - IDOV Methodology

Design for Six Sigma (DFSS) can be accomplished using any one of many methodologies. IDOV is one popular methodology for designing products and services to meet six sigma standards.

IDOV is a four-phase process that consists of Identify, Design, Optimize and Verify. These four phases parallel the four phases of the traditional Six Sigma improvement methodology, MAIC - Measure, Analyze, Improve and Control. The similarities can be seen below.

Identify Phase
The Identify phase begins the process with a formal tie of design to Voice of the Customer. This phase involves developing a team and team charter, gathering VOC, performing competitive analysis, and developing CTQs.

Crucial Steps:

Identify customer and product requirements

Establish the business case

Identify technical requirements (CTQ variables and specification limits)

Roles and responsibilities

Milestones

Key Tools:

QFD (Quality Function Deployment)

FMEA (Failure Means and Effects Analysis)

SIPOC (Supplier, Input, Product, Output, Customer product map)

IPDS (Integrated Product Delivery System)

Target Costing

Benchmarking

Design Phase
The Design phase emphasizes CTQs and consists of identifying functional requirements, developing alternative concepts, evaluating alternatives and selecting a best-fit concept, deploying CTQs and predicting sigma capability.

Crucial Steps:

Formulate concept design

Identify potential risks using FMEA

For each technical requirement, identify design parameters (CTQs) using engineering analysis such as simulation

Raw materials and procurement plan

Manufacturing plan

Use DOE (design of experiments) and other analysis tools to determine CTQs and their influence on the technical requirements (transfer functions)

Key Tools:

Smart simple design

Risk assessment

FMEA

Engineering analysis

Materials selection software

Simulation

DOE (Design of Experiments)

Systems engineering

Analysis tools

Optimize Phase
The Optimize phase requires use of process capability information and a statistical approach to tolerancing. Developing detailed design elements, predicting performance, and optimizing design, take place within this phase.

Crucial Steps:

Assess process capabilities to achieve critical design parameters and meet CTQ limits

Optimize design to minimize sensitivity of CTQs to process parameters

Design for robust performance and reliability

Error proofing

Establish statistical tolerancing

Optimize sigma and cost

Commission and startup

Key Tools:

Manufacturing database and flowback tools

Design for manufacturability

Process capability models

Robust design

Monte Carlo Methods

Tolerancing

Six Sigma tools

Validate Phase
The Validate phase consists of testing and validating the design. As increased testing using formal tools occurs, feedback of requirements should be shared with manufacturing and sourcing, and future manufacturing and design improvements should be noted.

Crucial Steps:

Prototype test and validation

Assess performance, failure modes, reliability, and risks

Design iteration

Final phase review

Key Tools:

Accelerated testing

Reliability engineering

FMEA

Disciplined New Product Introduction (NPI)

About The Author
David Woodford has a Ph.D. and a D.Sc from the University of Birmingham in England. He worked for GE in both the Turbine Technology Laboratory and in the Corporate R&D Center. From 1986 to 1994 he was Professor of Materials Engineering at Rensselaer Polytechnic Institute. He has published over one hundred and twenty papers in the general area of materials for energy conversion systems and has given numerous invited talks. Dr. Woodford is President, MPa, Inc. in Santa Barbara and Visiting Professor at the University of California at Santa Barbara.

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