In Six Sigma DMAIC, Quality Function Deployment (QFD) is a methodology and tool used in the Define stage. QFD is used to:
- Collect customer’s requirements/desires as specified by the customers in their own words
- Prioritize these desires
- Translate them into engineering/process requirements
- Establish targets to meet the requirements.
QFD is also termed as:
- Voice of the Customer
- House of Quality
- Customer-Driven Engineering
- Matrix Product Planning
QFD is a customer driven product or service planning process. It is a methodology for translating customer requirements into company requirements at each stage from Concept Definition (R&D) to Process Engineering and Production and into the marketplace. The QFD matrix is a tool to translate CCRs (Critical To Customers) into CTQs (Critical to Quality).
QFD collects the voice of the customer (VOC) in their own lingo and incorporates this VOC into the companies cross-functional team’s project management of the integrated development process. The QFD process establishes customer objectives and measures and records them on a series of matrices
This QFD matrix
QFD matrix translates the CCRs into CTQs. The final score helps prioritize the CTQs and helps you decide which CTQs to tackle first.
The QFD Methodology
- Identify both internal and external customers.
- Create a list of customer requirements/desires (Whats) by
- Asking the customer, questions such as “What are the important features of The Product”
- Capturing the customer’s own words or “Voice of the Customer” or VOC
- Categorizing the Whats into groups/buckets if needed.
- Prioritize the above collected Whats on a scale of 1-5, with 5 being the most important. This ranking is based on the VOC (Voice of Customer) data. The CCRs (Whats) are listed vertically in the first column and all related CTQs (Hows) are listed horizontally across the top . In the second column, assign 1 to 5 based on the importance of the CCRs, where 5 is the most critical to the customer.
- Score each CTQ (Hows) on how strongly it correlates to each CCR. Remember we are looking at the absolution value of the correlation. It could be either positively correlated or negatively correlated. Use 5 for a strong correlation and 1 is a weak one. Leave it blank if there is no correlation. Some CCRs will have few CTQs that relate and rest unrelated.
- Compile list of CTQs (Hows) necessary to achieve the CCRs (Whats.)
- Translate the CCRs from VOC (Whats) into CTQs (Hows)
- Arrows show direction for improvement (up for increasing, down for decreasing, etc.)
- For each What, find out the correlation with each How. If the correlation is strong use 5. If its week use 1. If its in between, use a number 2,3,4 based on how strong the correlation is.
- Next multiply the importance rating for the CCR by the correlation score for each CTQ.
- Add up the scores vertically for each CTQ and place that value in the bottom score row.
- Once the score is computed for all CTQs, the ones with the highest scores are the highest priority Six Sigma project objectives to work on.