Six Sigma initiatives have achieved
recent popularity because of their bottom line focus versus previous TQM
initiatives which often tended to be unfocused. General Electric, one of the
leaders in Six Sigma programs defines its key elements as:
- Critical to Quality: Attributes most important to the customer
- Defect: Failing to deliver what the customer wants
- Process Capability: What your process can deliver
- Variation: What the customer sees and feels
- Stable Operations: Ensuring consistent, predictable processes to improve
what the customer sees and feels
- Design for Six Sigma: Designing to meet customer needs and process capability
Design for Six Sigma (DFSS) is the application of
Six Sigma principles to the design of products and their manufacturing and
support processes. While DFSS can apply to
the design or a product, manufacturing process, business
process or service, our focus in the paper is the
development of new products. In one respect, DFSS is the repackaging of many quality tools
and techniques appropriate for product development into a framework. This framework contains
many of the same elements as the Advanced Product Quality Planning (APQP)
process used in the automotive industry.
Often the acronyms DMADV (define, measure, analyze, design and verify)
or IDOV (identify, design, optimize and validate)
are used to describe the Design for Six Sigma process.
ASQ’s Six Sigma Body of Knowledge covering
Design for Six Sigma (DFSS) lists the following subheadings:
- Quality Function Deployment (QFD)
- Robust design and processes (includes functional requirements)
- Failure Mode and Effects Analysis
- Design for X (DFX)
- Special design tools.
General Electric defines the principles of DFSS as the following:
- Disciplined CTQ flowdown
- Controlled design parameters
- Product performance modeled and simulated
- Designed for robust performance and producibility
- Functionally integrated product development
- Quality “designed in”
The following represents our more specific list of elements of the DFSS framework:
The Design for Six Sigma process is supported by our
Product Development Toolkit.
- Understand real customer needs through voice of the
customer (VOC) analysis.
- Use quality function deployment (QFD) to translate
customer needs into critical technical characteristics of the
product and ultimately into critical to quality (CTQ) characteristics of
the product and process.
- Focus on designing for the lifecycle to minimize lifecycle costs with
DFMA, value analysis and
target costing/DTC and to
enhance reliability with design for reliabilty
- Mistake-proof the product and process.
- Perform failures modes and effects analysis
(FMEA) or anticipatory failure determination
(AFD) to identify potential failures and take
corrective action to mitigate or prevent those failures. FMEA and AFD
apply to both the design of the product and the design of the process.
- Develop capable manufacturing processes and select processes that
are capable of meeting the design requirements, especially with CTQ
- Use design of experiments (DOE) or
Taguchi Methods to optimize parameter
values and reduce variation, in other words, develop a robust design.
Verify and validate the the product design will
meet customer needs with peer reviews, checklists, design reviews,
simulation and analysis, qualification testing, production validation
testing, focus groups and market testing.
- Measure results with DFSS scorecard; estimate sigma - do results
meet quality target?