This is because the focus of DFSS (design for six sigma) and DFLS (design for lean sigma) is our internal products and processes, whereas the focus of QFD (quality function deployment) is our customers. The differences between the sigma approaches and QFD are especially notable in these areas:
- Focus
- Customer understanding
- VOC (voice of customer) analysis
- CRM (customer requirements management) and priority
- Solutions identification and delivery
- Design, Development, and Commercialization
- Math
In short, QFD provides a holistic approach that links business, customer, and technology in one end-to-end trackable flow with the goal of customer value — DFCV (design for customer value). QFD uses quantitative and non-quantitative tools to analyze the unknown unknowns, information that leads to sustainable competitiveness.
DFSS provides a powerful set of statistical and analytic tools that can improve the efficiencies and effectiveness during the build of new products. QFD provides the umbrella of customer value as the driver and DFSS kicks in downstream to assure that solutions are optimally developed. We need both together in order to deliver customer satisfaction and business success.
Here is the detailed comparison of the sigma and QFD approaches and the reasons why we must use both: "DFSS/DFLS and QFD"