Question 5 of 5: Quality Function Deployment (QFD) — purpose and procedure

Question 5: Quality Function Deployment (QFD) — purpose and procedure (20 marks)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

Purpose. QFD is a structured design-planning method whose purpose is to translate the customer's own words about what they want (often vague, e.g. "feels sturdy", "easy to carry") into specific, measurable engineering targets that the design team can actually design and test against, while simultaneously tracking how the design compares to competitors' products on those same customer wants. Its core value is traceability: every engineering specification in the final product can be traced back to a customer need that justified it, so the team is prevented from over-engineering features nobody asked for or missing a requirement customers actually care about. It also surfaces conflicts early — where improving one engineering characteristic necessarily degrades another — while the design is still just a matrix on paper, not a physical prototype.

General procedure (the "House of Quality"). QFD is usually carried out by building a single matrix, nicknamed the House of Quality because of its roof-shaped correlation section, in the following general sequence:

1) Gather and list customer requirements ("the WHATs"). Voice-of-the-customer data (interviews, surveys, complaint records, focus groups) is distilled into a prioritized list of customer needs, each given an importance weighting (e.g. 1–5) reflecting how much customers care about it.

2) Identify engineering characteristics ("the HOWs"). The design team lists the measurable technical characteristics (dimensions, materials, forces, response times, tolerances, etc.) that the team can control and that plausibly affect one or more customer requirements.

3) Build the relationship matrix. Every WHAT is checked against every HOW, and a symbol or weight (e.g. strong/medium/weak, or 9/3/1) is entered where a real relationship exists, showing which engineering characteristics actually influence which customer wants.

4) Add the roof — the correlation matrix. The triangular "roof" above the HOWs records how the engineering characteristics interact with each other: a strong positive correlation (improving one improves the other, e.g. lighter weight and lower cost may align) or a strong negative correlation / trade-off (improving one degrades another, e.g. higher strength and lower weight often conflict), flagging where the design team must consciously balance competing targets.

5) Competitive benchmarking. Alongside the WHATs, the team scores its own planned product and one or more competitor products against each customer requirement, revealing where the new design must at least match or beat the competition to win on a feature customers already care about.

6) Calculate importance ratings and set targets. Using the importance weighting from step 1 and the relationship strengths from step 3, a weighted score is computed for each engineering characteristic (its total contribution to satisfying customer needs), which the team uses to prioritize where design effort and cost should go, and to set a specific numeric target value for each engineering characteristic.

7) Carry targets forward. The engineering-characteristic targets from this first House of Quality become the "WHATs" of a second-level QFD matrix (translating them into part characteristics), which in turn can feed a third (process planning) and fourth (production/quality-control planning) matrix, cascading the original voice of the customer all the way down to the shop floor.