Quality function deployment (QFD) bezeichnet eine Methodik anhand formalisierter Dokumente zur Systematisierung der umfassenden Qualitätsplanung im Zusammenhang mit der Erstellung eines Leistungsangebots. Hierbei erfahren Kundenbedürfnisse eine ständige Berücksichtigung. Grundlage des QFD ist eine Matrixanordnung, die die verschiedenen Ablaufschritte abdeckt und aufgrund ihrer spezifischen Form als „House of Quality“ bezeichnet wird.
The goals of the QFD include the development of better solutions through the cooperation of all departments involved in the development and product creation process; the determination of cost-effective solutions through a forward-looking, preventive avoidance of undesirable developments; the implementation of customer-oriented solutions through early consideration of market and customer information as well as translation of the “voice of the customer” into the “technical language of the developer”; the shortening of the development time through a well-founded product definition and consequently minimal product changes as part of the product development process.
The QFD process is usually described in terms of four phases:
Product quality plan: In this phase, customer needs are determined and translated into the resulting quality characteristics.
Quality plan construction / parts: On the basis of the determined quality characteristics, the planning of assemblies, parts, components and construction planning is carried out in the next phase.
Quality plan process: The critical partial characteristics found in the preliminary phase are the starting point for planning the manufacturing processes. In this phase the critical process parameters are analyzed and documented.
Production quality plan: The considerations of the preceding phases lead to the concrete planning of the production. This phase is used to provide a detailed description of the procedures through to the work instructions.
In each of these phases, a matrix is created based on the values derived in the previous phase (“House of Quality”). The nine steps for the implementation of the "House of Quality" are to be presented using the product quality plan:
Recording of customer requirements: through market research and customer surveys, all product features that are important for the customer are determined.
Weighting of customer requirements: Since not all criteria are likely to be of equal importance for the customer, the preferences of the customers and corresponding weightings are also recorded. Methods such as multidimensional scaling or conjoint measurement can be used for this purpose.
Competitive analysis of the fulfillment of the requirements from the customer's point of view: If the company already has a model of a similar product, a comparison with the most important competitors with regard to the fulfillment of customer requirements must be made on this basis (product reverse engineering).
Deriving the technical characteristics: The customer requirements determined are converted into technical characteristics. These should be in line with requirements and as quantifiable as possible.
Showing the interdependencies between the technical characteristics: Especially in the case of complex customer problems, the dependencies between the technical specifications must be clarified in order to reveal complementary, neutral or conflict-prone relationships.
Creation of a relationship matrix: The next step is to systematically examine the extent to which each technical requirement influences the individual customer wishes. Conflicts of objectives can arise here if a certain technical detail hinders the fulfillment of one or more customer requests. This phase of the QFD shows whether a chosen solution approach can still be pursued or whether significant reductions have to be made with regard to the customer-related "ideal solution". In the latter case, it is better to choose a different solution model.
Quantifying the technical specifications: The technical features are now specified in more detail, specifying quantifiable measurement criteria, e.g. insulation in decibels (db), weight in kilograms (kg). Customers who use the product to be developed as an investment good have relatively specific ideas (ordinal or even cardinal data) about the characteristics of the individual requirements. The ideal profile of these characteristics can also be derived using the multidimensional scaling or conjoint measurement methods.
Competitive analysis of characteristics of the technical features from the manufacturer's point of view: Where there are comparable competing products, it is advisable to carry out a comparison with these. Customer requests with high priority should be implemented with technical specifications that are superior to the competing product.
Evaluation of the technical features with regard to their importance for the fulfillment of customer needs: It is based on the sum of the proportions of the respective technical feature in the fulfillment of all customer requirements.
Key problem areas of the QFD are, in addition to a high level of effort in terms of time, personnel, cost-intensive and planning, the recording of customer needs and the risk of translation errors when converting the formulated customer request into technical language. When using the QFD, this results in the need to include other quality management tools. There are numerous methods that can be used to support the quality inspection, particularly for recording customer requirements.