QFD House of Quality: From Customer Needs to Engineering Characteristics
What is QFD?
QFD (Quality Function Deployment) systematically translates customer needs into engineering characteristics and process control requirements, with the house of quality as its core tool. It keeps the voice of the customer throughout design so engineers do not rely on gut feeling. QFD is widely used in early APQP planning and Six Sigma DFSS projects, and combining it with the KANO model lets you classify needs before deployment.
The Structure of the House of Quality
The house has six parts: the left wall (customer needs and their importance), the ceiling (engineering characteristics), the room (relationship matrix between needs and characteristics), the roof (correlations between characteristics), the floor (importance ranking of characteristics and technical targets) and the right wall (competitive assessment). The tool guides you block by block and automatically computes engineering characteristic importance by summing need importance times relationship strength, so the top-ranked characteristics become design priorities.
How to Fill the Relationship Matrix
Use relationship strengths of 9 (strong), 3 (moderate) and 1 (weak), leaving blanks for no relationship; the tool handles the weighting automatically. Mark conflicts between characteristics with positive and negative signs on the roof (for example cost versus performance), since conflicting pairs often become the targets of later DOE and Taguchi experiments. Have a cross-functional team of market, R&D, quality and process people fill it together to avoid one-sided bias.
Step-by-Step Usage
Collect VOC and set need weights (with the KANO tool if needed), list corresponding engineering characteristics, fill the relationship matrix and roof, review the importance ranking and conflicts, then convert high-importance characteristics into target values and control plan inputs. The QFD output feeds directly into DFMEA for critical characteristics and into the APQP special characteristics list. Update the house as requirements change so design targets always track the latest customer voice.