Having a design that provides the right features that work as required is what design for Six Sigma is all about. Design for Six Sigma, or DFSS, is a systematic methodology for the design or redesign of products, processes, and services. The goal is to ensure that design meets or exceeds customer expectations and key requirements.
The greatest difference between the two roadmaps lies in their unique purposes. The DMAIC roadmap resources are spent on reducing waste, cost or time in a process, while DMADV resources are focused on preventing potential losses.
Let’s talk about some characteristics of DFSS:
- First, quality is designed in instead of inspected in. That is, the process, product, or service itself is crafted to ensure quality rather than relying on end of the line inspection checks.
- Next, customer expectations and key requirements are prioritized and incorporated into the design from the start. In DFSS, we call this requirements flow down. It ensures there is a link between customer requirements and functional product and process requirements.
- Lastly, quality is predictable. There are no surprises. The capability of the design is predicted as the project progresses to ensure that design is capable of meeting customer requirements and performance targets.
Table 1: A Brief Comparison of the DMAIC and DMEDI Six Sigma Roadmaps | |
DMAIC | DMADV |
Define – Determine Project Scope, Objectives, Resources, Constraints | Define – Very Similar to DMAIC, Scope, Objectives, Resources, Constraints |
Measure – Determine Customer Groups, Determine CCRs, Obtain Data to Quantify Process Performance | Measure – Define Customers and Needs Using Voice of the Customer and QFD, Determine CCRs |
Analyze – Analyze Data to Identify Tangible Root Causes of Defects | Analyse – CTQs are examined, functional requirements, , and High-Level Design to match functional requirements |
Improve – Intervene in the Process to Improve Performance, Pilot New Process | Design – Develop Design Concepts, Select Design concept, Develop and Optimise Detailed Design |
Control – Implement a Control System to Maintain Performance Over Time | Validate– Validate Design with Pilot, Establish Controls, Full-Scale Implementation |
DFSS projects follow a five phase methodology. Define, measure, analyze, design, and verify, or DMADV, pronounced as de-mad-vee.
- In the define phase, the business case for the design project is established and the project charter, including objectives, scope, goals, and design team, are approved. This phase establishes the reason for the design effort and helps keep the team focused.
- Next, in the measure phase, VOC, or voice of the customer analysis, is tear down. Customer needs are identified, prioritised, and translated into measurable requirements called critical to quality requirements, or CTQs. CTQs are the performance characteristics that are critical in satisfying customer needs. For example, for a coffee maker, VOC efforts may identify the top three customer needs as suits my taste, easy to use, and fresh coffee when I want it. We could translate the need for fresh coffee when I want it into three CTQs, brews quickly, adjustable amount of coffee, and fast total time from start to finish. A scorecard called a design scorecard is established to score and track design capability against CTQs and performance targets throughout each phase.
- In analyse phase, CTQs are examined to determine the functions of functionality needed, that is we need to find out what does the product or service need to be able to do to meet those CTQs? These functional requirements drive the generation of conceptual designs and the best is selected.
- During the design phase, product features are created and specifications are finalised. Process requirements are developed and parameters are optimized.
- And last, in the verify phase, the final design is agreed upon and tested to make sure it is producible and still meets customer needs. Controls are designed and implementation then takes place.
Sometimes in a D-mac DMAIC project, after the A, or analyze phase, a redesign effort may be required. In that case, a mini DMADV cycle can deliver the design as part of the improve phase.
Table 2: Benefits Each Roadmap Provides for Real World Business Environments | ||
DMAIC | DMADV | |
Transactional Business Environment | > Reduce cycle time and errors on service orders > Increase first call resolution on support calls > Reduce service order cycle time | > Design a new project management office > Develop a new service order handling process > Develop a new contract renewal process |
Service/- Manufacturing Environment | > Reduce product manufacturing/assembly cycle time > Provide IT solutions – improve backup and recovery time, reduce patching time > Identify causes and eliminate defects in molds > Eliminate false server alerts | > Major redesign of manufacturing process (conversion from gasoline to alcohol engines) > Weld new materials > Design new triage process for new technologies > Develop new formats for storing larger data files |
Product Development Environment | > Reduce product development cycle time > Identify causes of defects in a copier design > Reduce defects released in new software versions | > New fuel injection design > New material development > Next generation ink delivery system |