Quality Function Deployment

* Methodology for defining the customer's desires in the customer's own words, prioritizing these desires, translating them into engineering requirements, and establishing targets for meeting requirements.

Tool for defining the "right" problem to solve.
-Developed in Japan in 1970's - Mitsubishi & Toyota
-Introduced in US in 1980's (Hauser and Clausing, Harvard Business Review, May-June 1988).

*Also known as:

-Voice of the Customer
-House of Quality
-Customer-Driven Engineering
-Matrix Product Planning

*Uses a series of matrices to structure information acquisition and documentation.

QFD Matrices

Figure 1. General organization of a QFD matrix.

QFD Methodology

1. Identify customers (both internal and external).
2. Create a list of customer requirements (WHATS).

* Record customer responses to the question: "What are the important (qualities, characteristics, elements, features) of _____________?"
* Record in customer's own words - "Voice of the Customer."
* Categorize hierarchically (primary, secondary, tertiary,...).

3. Prioritize the customer requirements on a scale of 1-5.
4. Compile list of design requirements (HOWS) necessary to achieve the market-driven whats.

* Each requirement should be quantified.
* Arrows show direction for improvement (up for increasing, down for decreasing, etc.)

Figure 2. Start with WHATs and HOWs.

5. Determine relationship of design requirements to customer requirements.

* Cell strengths quantify the importance of each HOW to achieving each WHAT.

Strong relationship
Some relationship
Weak relationship
No mark for no relationship

Figure 3. Adding correlations between WHATs and HOWs.

6. Determine how the customer perceives competitors' abilities to meet requirements.

* Competition benchmarking.
* Rate competitors on a scale of 1-5 with respect to each customer requirement.

7. Rank the technical importance of each design requirement.

* Absolute rank is total of relationship value (quantify step 5 relationships) times customer importance ranking.
* Relative importance is based on assigning ordinal ranking to each design requirement based on absolute rank (from previous step).

8. Rate the technical difficulty of each design requirement so design team can focus on the important/difficult HOWS.
9. Establish correlation matrix (roof of House of Quality) to determine interrelationships of design requirements.

Strong positive interaction
Positive interaction
Strong negative interaction
Negative interaction

10. Determine target values for the design requirements (HOW MUCH).
11. Areas that require concentrated effort are identified. Key elements are identified for follow-up matrix development. Assessment of technical difficulty and importance are useful in identifying these elements.

Figure 4. QFD matrix with objective measures added.

Figure 5. Completed QFD matrix.

QFD: Summary

* The importance of QFD:

- Provides a framework for upfront planning and product development.
- Uses multi-functional teams to enhance design and decision-making.
- Promotes teamwork (necessary for Concurrent Engineering).
- Maintains customer ideas and requirements, in the customer's words, throughout the process.

* Engineered products adhering to customer wants result in customer satisfaction.