Quality Function Deployment (QFD) :
The use of QFD would enlarge the chance of success, produce higher quality products and decrease the cost and the development time.
It is a method to encourage product development
team members to communicate more effectively
with each other using a complex set of data. It helps
teams to formulate business problems and possible solutions. It also involves the voice of the customer.
QFD was invented in the late 1960s in Japan to support the product design process.
The (7) major benefits of using QFD
- QFD helps companies to make the key trade-offs between what the customer demands and what the company can afford to produce.
- QFD improves effective communication between company divisions and enhances team work.
- Quality is built in upstream.
- QFD increases customer satisfaction by making sure that customer demands are brought into the product development process.
- Important production control points are not overlooked.
- QFD brings together all the data required for the development of a good product and the development team sees very quickly where additional information is needed during the process. Moreover, the information is better used and documented.
- QFD shortens time-to-market.
The first matrix of the QFD method is called the House of Quality
It consists of several so-called rooms, each containing information concerning the product. The main goal is to translate the Customer Demands into Product Requirements.
The House of Quality only provides a company with the goals they should try to reach in the intended product, but it does not tell what part, processes or production plan the company needs to realise these goals
The construction of the House of Quality starts with the determination of the customer demands, often called the WHATs (1a). Other terms used are voice of the
customer, or quality characteristics.
The customer demands are rated against each other to quantify their importance in realising the success of the product. This IMPORTANCE RATING can help to set priorities for the product development process and provide guidelines to allocate the necessary resources.
On the right hand side of the house is the CUTOMER COMPETITIVE ASSESSMENT (1b) section, which contains information on the customer’s perception of the company’s product compared to competitor’s products.
The room on the upper side of the House of Quality is the Product Requirements section, which gives a technical description of how to realise the consumer demands in the product. These product requirements are also called the HOWs (2), or substitute quality characteristics, and represent a translation from the customer’s language into the company’s technical language
The centre part of the House of Quality contains the relationships, and depicts the relationship and strength
between each WHAT and HOW. This RELATIONSHIP MATRIX (3) also provides a crosscheck: blank rows or columns indicate that a WHAT has inadequately been translated into a HOW
The CORRELATION MATRIX (4), put in the roof of the House of Quality, contains the correlations between the HOWs and shows what HOWs influence each other. Its use is to show where trade-off decisions have to be made.
Positive correlations between HOWs show that they
support each other. Negative correlations show that the HOWs adversely affect each other
The bottom of the House of Quality contains several
rooms with different types of information. One section
contains the HOW MUCHs (5); these are the measurements for the HOWs. The use of the HOW MUCH section is to determine priorities and directions for improvements of the HOWs and to provide an objective
means of assuring that requirements have been met
Other rooms on the bottom of the House of Quality
are the Technical Competitive Assessment (6), showing the technical benchmarking of the product. The Technical
Importance Rating (7) provides a relative importance of
each HOW in achieving the collective WHATs
The construction of the next matrix is started by placing
all or the most important HOWs of the House of Quality on the left-hand side of the second matrix and their priorities on the right hand side.
The HOW MUCHs are also placed in the next matrix to facilitate communication, ensuring that the target values are not lost. Only those HOWs which are new, important, or difficult and therefore high risk to the company are taken into the next phase of the QFD method (ASI, 1992).
In this way the HOWs of the first matrix become the WHATs of the second matrix . Every matrix along the cascading process contains more detailed information concerning the product.
The most used and described QFD model to go
beyond the House of Quality is the Four-Phase model,
also known as the ASI model or Clausing model.
(2) The design deployment
matrix (part deployment)
(3) The manufacturing
planning matrix (process planning)
(1) The product planning
matrix (the House of Quality)
(4) The production
planning matrix (production operations planning)