Quality Function Deployment (QFD)

Dr Mizuno, Professor Emeritus of the Tokyo Institute of Technology, is credited with initiating the quality function deployment (QFD) system. QFD can be applied practically to all industries in the manufacturing and service sector. QFD is a planning tool used to fulfill customer expectations.5 It focuses on customer requirements, often referred to as the voice of the customer and is a disciplined approach to product design, engineering and production and provides in-depth evaluation of a product. An organization that correctly implements QFD can improve engineering knowledge, productivity, quality and reduce costs, productdevelopment time and engineering changes. It is employed to translate customer expecta­tions, in terms of specific requirements, into directions and actions and in terms of engi­neering characteristics that can be deployed through product planning, part development, process planning, production planning and service planning.

QFD is a team-based management tool in which customer expectations are used to drive the product development process. The QFD technique consists of a series of interlocking matrices that translate customer needs into product and process characteristics. QFD yields the following benefits:

• It facilitates identification of the causes of customer complaints and makes it easier to take prompt remedial action.
• It is a useful tool for improving product quality.
• It is a useful tool for competitive analysis of product quality.
• It stabilizes quality.
• It cuts down on rejects and rework at the production site.
• It decreases claims substantially.

1. House of Quality

The house of quality is the primary planning tool used in QFD. The house of quality translates the voice of the customer into design requirements that meet specific values and matches those against the way in which an organization meets those requirements. Many managers and engineers consider the house of quality to be the primary chart in quality planning. The structure of QFD can be thought of as a framework of a house as shown in Figure 9.2. This is the basic structure for the house of quality.

2. Building the House of Quality

The following steps can be used to build the house of quality:

Step 1 List customer requirements: The left exterior wall of the house represents the cus­tomer requirements. It deals with the “Whats” that a customer needs or expects in a par­ticular product. The list of customer requirements is divided into a hierarchy of primary, secondary and tertiary customer requirements.

Step 2 List technical descriptors: The ceiling or second floor of the house contains the technical descriptors. The goal of the house of quality is to design or change the design of a product in such a way that it meets or exceeds the customer expectations. Each engineering characteristic must directly affect a customer’s perception and be expressed in measurable terms. These characteristics are an expression of the voice of the customer in technical lan­guage. Brainstorming among the engineering staff is a suggested method for determining the technical descriptors.

Step 3 Compare the relationship between customer requirements and technical descrip­tors: The next step in building a house of quality is to compare the customer requirements and technical descriptors and determine their respective relationships. The interior walls of the house are the relationships between customer requirements and technical descriptors. Customer expectations (customer requirements) are translated into engineering characteris­tics (technical descriptors).

Step 4 Develop an interrelationship between each of the technical descriptors: The roof of the house is the interrelationship between technical descriptors. Trade-offs between similar and/or conflicting technical descriptors is identified.

Step 5 Implement competitive assessments: The competitive assessments are separated into two categories, customer competitive assessment and technical competitive assessment as shown in Figure 9.3. The customer competitive assessment is a good way to determine if the customer requirements have been met and to identify areas to concentrate on in the next design. The customer competitive assessment also contains an appraisal of where an organi­zation stands relative to its major competitors in terms of customer requirements.

The technical competitive assessment is often useful in covering gaps in engineering judgement. When a technical descriptor directly relates to a customer requirement, a com­parison is made between the customer’s competitive evaluation and the objective measure ranking. Customer requirements and technical descriptors that are strongly related should also exhibit a strong relationship in their competitive assessment. Both assessments are important, because they give the organization an understanding on where its product stands in relationship to the market.

Step 6 Develop prioritized customer requirements: The right side exterior wall of the house of quality represents the prioritized customer requirements corresponding to each custom­er’s competitive assessment in the house of quality.

Step 7 Develop prioritized technical descriptors: The foundation of the house represents the prioritized technical descriptors. The QFD team identifies technical descriptors that are most needed to fulfill customer requirements and needs improvement. These measures pro­vide specific objectives that guide the subsequent design and provide a means of objectively assessing progress and minimizing subjective opinion.

Source: Poornima M. Charantimath (2017), Total Quality Management, Pearson; 3rd edition.