Quality function deployment
Quality function deployment (QFD) is a method developed in Japan beginning in 1966 to help transform the voice of the customer [VOC] into engineering characteristics for a product. Yoji Akao, the original developer, described QFD as a "method to transform qualitative user demands into quantitative parameters, to deploy the functions forming quality, and to deploy methods for achieving the design quality into subsystems and component parts, and ultimately to specific elements of the manufacturing process." The author combined his work in quality assurance and quality control points with function deployment used in value engineering.
The QFD method identifies and classifies customer desires, identifies the importance of those desires, identifies engineering characteristics which may be relevant to those desires, correlates the two, allows for verification of those correlations, and then assigns objectives and priorities for the system requirements. This process can be applied at any system composition level (e.g. system, subsystem, or component) in the design of a product, and can allow for assessment of differently level abstraction systems based on the output of QFDs matrices assessed for those system levels. The output of the method is generally a matrix with customer desires on one dimension and correlated nonfunctional requirements on the other dimension. The cells of matrix table are filled with the weights assigned to the stakeholder characteristics where those characteristics are affected by the system parameters across the top of the matrix. At the bottom of the matrix, the column is summed, which allows for the system characteristics to be weighted according to the stakeholder characteristics.
System parameters not correlated to stakeholder characteristics, may be unnecessary to the system design and are identified by empty matrix columns, while stakeholder characteristics (identified by empty rows) not correlated to system parameters indicate "characteristics not address by the design parameters". System parameters and stakeholder characteristics with weak correlations potentially indicate missing information, while matrices with "too many correlations" indicate that the stakeholder needs may need to be refined.
Areas of application
QFD is applied in a wide variety of services, consumer products, and military needs.
The concepts of fuzzy logic have been applied to QFD ("Fuzzy QFD" or "FQFD"). A review of 70 papers in 2013 by Abdolshah and Moradi found a number of conclusions: most FQFD "studies were focused on quantitative methods" to construct a QFD matrix based on customer requirements, where the most-employed techniques were based on multiple-criteria decision analysis methods. They noted that there are factors other than QFD relevant to product development, and called metaheuristic methods "a promising approach for solving complicated problems of FQFD."
Derived techniques and tools
- House of quality
- The house of quality appeared in 1972 in the design of an oil tanker by Mitsubishi Heavy Industries. Akao has reiterated numerous times that a house of quality is not QFD, it is just an example of one tool.
- Pugh concept selection
- Pugh concept selection can be used in coordination with QFD to select a promising product or service configuration from among listed alternatives.
- Modular function deployment
- Modular function deployment uses QFD to establish customer requirements and to identify important design requirements with a special emphasis on modularity. There are three main differences to QFD as applied in Modular Function Deployment compared to House of Quality:
- The benchmarking data is mostly gone.
- The checkboxes and crosses have been replaced with circles.
- The triangular “roof” is missing.
- There are also other minor differences between the application of QFD in modular function deployment as compared to House of Quality, for example the term "Customer Attribute" is replaced by "Customer Value", and the term "Engineering Characteristics" is replaced by "Product Properties". But the terms have similar meanings in the two applications.
- Akao, Yoji (1994). "Development History of Quality Function Deployment". The Customer Driven Approach to Quality Planning and Deployment. Minato, Tokyo: Asian Productivity Organization. ISBN 92-833-1121-3.
- Larson et al. (2009). p. 117.
- Larson et al. (2009). p. 119.
- "Quality Function Deployment (Draft)" (PDF). di.ufpe.br. Archived (PDF) from the original on March 3, 2016.
- Abdolshah, Mohammad; Moradi, Mohsen (2013). "Fuzzy Quality Function Deployment: An Analytical Literature Review". Journal of Industrial Engineering. doi:10.1155/2013/682532.
- Hauser, John R.; Clausing, Don. "The House of Quality". Harvard Business Review. No. May 1988. Archived from the original on April 16, 2016.
- "Frequently Asked Questions about QFD". QFDI.org. QFD Institute. Archived from the original on December 13, 2013.
- Börjesson, Fredrik; Jiran, Scott. "The Generation of Modular Product Architecture Deploys a Pragmatic Version of Quality Function Deployment". Archived from the original on December 31, 2012. (registration required (. ))