The essence of quality function deployment (QFD) lies not in the creation of matrices such as quality tables, but in the application of the three principles described in this chapter to real-life situations. The application of these three principles to real-life situations is the true implementation of QFD, and quality tables are simply examples of that implementation.

The three principles of QFD are analysis and integration, diversification and visualization, and generalization and localization.

The principle of analysis and integration obviously refers to the process of splitting things up and putting them back together. Splitting things up as you think about them is an important part of the quality deployment. The functionality of a product is differentiated from the achievement level of that functionality, as required quality in the world of the market is differentiated from quality characteristics in the world of technology. Cost issues are differentiated from quality issues. The word analyze means to take apart and understand, and much can be learned by thinking about a product’s component elements.

The customer’s needs can be organized in a deployment table so that they can be analyzed and re-integrated. There are different techniques that can be used, such as the deployment of required quality from upper levels of the hierarchy or extracting and integrating items from lower levels of the hierarchy, but it is the latter of these two approaches that are most commonly used. In other words, analysis and integration. A method for generating ideas is also important when integrating in order to ensure that you are not constrained by conventional concepts and are able to reintegrate using new ideas. This should enable you to discover new ideas both while analyzing and while reintegrating.

The principle of diversification and visualization is intended to help evolve a fixed perspective into a flexible one and to arrange data so that it can be viewed visually. As to the question of the potential for establishing design quality by using a quality table to understand critical quality characteristics, this can be determined using a quality characteristic deployment table and function deployment table. In other words, the determination of whether the design quality targets are achievable with the functionality built into the product. As for the question of whether that functionality can be achieved by the mechanism under consideration, this can be determined using function deployment tables and mechanism deployment tables.

Theses tables, which comprise a two-dimensional matrix, are a convenient method for understanding the relationship between two things, not to mention that deployment tables and matrices can be viewed by others. In other words, by organizing the data in a manner than can be easily viewed and understood, it is possible to obtain corrections and comments from a third party. Unlike a verbal exchange of opinions, the preparation of visual information leaves a record that permits knowledge to be accumulated.

Principles of QFD

1. Analysis and Integration

  • 1.1  Careful analysis is an important aspect of quality deployment.
  • 1.2  Separate a product’s main functions from the quality needed to achieve that functionality.
  • 1.3  Separate the required quality of the world of the market from the quality characteristics of the world of technology.
  • 1.4  Separate cost issues from quality issues
  • 1.5  Organize the deployment table so that items are first analyzed and then reintegrated.
  • 1.6  Analysis and integration is the first principle of QFD

2. Diversification and visualization

  • 2.1  Study items that have been analyzed and summarized in the deployment table from a variety of perspectives.
  • 2.2  A house of quality is a two-dimensional matrix studying the world of the market and the world of technology.
  • 2.3  Deployment tables and matrices are visualizations of data that can be viewed by a third party.
  • 2.4  Visualization of data makes it possible to obtain corrections and comments from a third party.
  • 2.5  Diversification and visualization is the second principle of QFD

3. Generalization and localization

  • 3.1  Use a bird’s-eye view of the whole to ascertain critical components.
  • 3.2  Critical components can be expanded and studied in detail.
  • 3.3  What is optimal for a particular component is not necessarily optimal for the whole.
  • 3.4  It is important to achieve a balance between generalization and localization.
  • 3.5  Generalization and localization is the third principle of QFD.

The principle of generalization and localization is concerned with the overall balance of the whole with individual components. A quality table represents the simultaneous diversification and visualization of information and is necessary to obtain a bird’s-eye view of the overall situation in determining which sections are most critical. Critical sections can then be expanded and studied in detail. The repetition of this process then leads to the establishment of effective quality assurance. Diagram “Extracting Data from Quality Tables” is an illustration of this concept.

For example, in order to obtain an overall understanding, the secondary items of both the required quality and quality characteristic sections can be used in the creation of a matrix. This matrix will be no larger than 30 by 30 items and can be used to obtain an overall view. This type of operation is what is meant by generalization and localization, which is an activity for focusing on critical points.

The reason for performing this operation is that what is optimal for a particular component may not be what is optimal for the whole. It is necessary to always keep in mind which component is being studied and how the results of that study will affect the whole.

Extracting Data from Quality Tables

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