Quality function Deployment

1. Quality function Deployment 設計方法 朝陽科技大學工業設計系 林登立助理教授

2. product opportunity • A product opportunity is a mis-match between the needs of customers and the offerings of competing products. • The description of that product opportunity is, and always should be, phrased in terms that customers would understand and that they themselves might use. • The new product should be cheaper, have more features, look more attractive or do things that no other product currently does.

3. 強烈的市場導向 • 以這種方式描述產品機會有許多優點。 • 第一是它可以使產品機會簡單易懂，而且具有強烈的市場導向。 • 其次是它確立了產品開發的目標，但卻不限制其達成手段。

4. 描述產品機會 • 但是，在某些時間點，需要使用技術性的方式說明產品機會。 • 設計程序的最終結果是產品製造規格書，它所使用的語句基本上和消費者常用的語彙有所不同。 • 對於一般消費者而言，產品所必須使用的材料名稱可能汲有任何意義。他們可能從沒聽過生產製造程序或工程公差。 • 重要的問題是要能適當的區別何時要用消費者導向的語句，何時要用技術性專業術語去描述產品機會。

5. direction for further development • It is a fundamental principle of effective product development that this translation form customer needs into technical objectives should happen before the start of the design process. • Developing a technical design specification from the opportunity specification is a pre-requisite for quality controlling the design and development process. • It is only by referring to the design specification that emerging new product can be judged to be progressing satisfactorily, and given direction for its further development. • Alternatively, the product is judged to be unsatisfactory and killed off, before further resources are wasted on its development.

6. two functions of quality control • A quality ‘guidance’ function which targets the development process progressively more closely to the achievement of customer satisfaction. • A quality ‘gating’ function which reviews the progress of the new product against targets and only allows through the products meeting the necessary targets.

7. Guiding and gating

8. utility, accuracy and fidelity • In preparing a design specification, achieving utility means making the specification useful for the purposes of quality controlling product development. • The design specification must, therefore, be described with sufficient precision to allow technical decisions to be made. • These precise descriptions in the design specification must be an accurate reflection of the customer’s needs and wishes. • The design specification must have fidelity to customer needs.

9. difficult & important • The preparation of this design specification is as difficult as it is important. • Get it wrong and you may end up with a product that has been perfectly quality controlled in entirely the wrong direction.

10. human brain is particularly poor • Getting this design specification to translate customer requirements accurately and with utility and fidelity is a fundamentally difficult task. • In the language of problem solving, this is a complex (problem solving involves several stages), fuzzy (the problem boundaries are ill-defined), multi­factorial (there are many different variables to consider) problem requiring simultaneous ( as opposed to sequential) resolution. • It is an unfortunate fact of life that the human brain is particularly poor at this sort of problem solving.

11. the need for humility in the design profession • the development of a design specification is a task for which you need help. • The difficulty people have with complex information processing must be acknowledged and assistance sought for a design task, for which we have been less than perfectly designed ourselves. • Designers need help to effectively translate customer needs into a design specification. • That help comes in the form of quality function deployment.

12. four main stages to quality function deployment • a matrix is developed to explore the technical attributes of a product which contribute to customer needs. • competing product analysis ranks the performance of existing products in terms of both customer satisfaction and technical performance. • quantitative targets are set for each of the technical attributes of the product and • these targets are prioritised.

14. Stage 1: The heart of quality function deployment • At the heart of both the procedure for quality function deployment and the house of quality diagram is the translation matrix or relationship matrix. • This matrix translates individual customer needs into specific technical design requirements by a systematic step-by step process. • The process starts by listing all the identified customer needs and arranging them in rows down one side of the matrix. • Then design requirements for satisfying these customer needs are arranged in columns along the top of the relationship matrix. • The extent to which each of these technical parameters relates to each customer need is identified in the matrix.

15. strength of the relationship • The coding system for the matrix is arbitrary but it should indicate the strength of the relationship and • whether it is positive (i.e. makes a positive contribution towards sat­isfying customer needs) or negative (i.e. detracts from the satisfaction of customer needs)

17. Stage 2: Competing product analysis • Competitor analysis takes two forms in quality function deployment. • Firstly, customers give a rating of competing products on each of their stated customer requirements. • Secondly, the design team examines each competing product on each of their design requirements. • Two competing thumb tacks were analysed, as well as the company's own existing product (Figure 8.6). • The ratings for both customer and design analysis were made on a 1 (worst) to 5 (best) scale.

19. Stage 3: Setting quantitative targets • Having seen how competing products compare both technically and in the eyes of customers, we are now in a position to set design targets for the proposed new product. • The table (Figure 8.7) shows how the three current products compare on the four design features.

20. target design values

22. Stage 4: Prioritising the design targets • Once the design targets are identified, it is important to know which are the most important so that maximum effort is invested in meeting, or exceeding, the most important ones. • It is also possible that certain design targets will have to be compromised in order to resolve conflict between them (e.g. conflict between improved features and reduced cost). • In order to do so systematically, each design target is given an importance rating. • This rating must be a reflection of their importance for achieving customer satisfaction. • Consequently, they are based on the customers' ratings of the importance of the different customer requirements.

27. Printing http://www.teamset.com/tools/qfd/qfd.html

37. importance rating • During the research into customer ratings of competing products, customers would have been asked to give a score from 1 to 10, indicating the importance of each customer requirement. • This is entered into the house of quality diagram alongside each of the customer requirements. • Then, using a scoring system for each type of relationship within the relationship matrix, an importance rating for each design requirement is calculated

38. importance ratings is arbitrary • The scoring system used to calculate importance ratings is arbitrary. • Scales of either 1 to 5 or 1 to 10 are most common, since this allows a significant differentiation between important and unimportant factors (Figure 8.10). • What is important about the scoring system is that it gives importance ratings which intuitively feel right. • If they do not feel right, adjust the' numbers slightly on the relationship scores to see if a more intuitively reasonable importance rating is produced. • The customer ratings should not be adjusted so arbitrarily since they are derived from market research. • If, for any reason they do not 'feel' right, the market research should be repeated.

39. beyond product planning • Quality function deployment can be used throughout the design process, not just in the product planning stages. • The house of quality is turned into a street of quality in which the outputs from one quality function deployment exercise become the input into the next quality function deployment analysis. • In this way, quality can be systematically and rigorously steered from product planning to manufacturing and assembly.

40. outputs can be taken as inputs • The quality function deployment procedure we have just been through takes customer requirements as inputs and translates them into design specifications as outputs. • These outputs can be taken as inputs into the second house of quality and turned, just as systematically into product specification outputs. • So, we concluded in the analysis of the thumb tack that the design specification should include diameter of head, diameter of pin, strength of join and sharpness of pin. • Imagine taking these requirements and placing them in the house of quality where we previously put customer requirements. • This would give us a relationship matrix from design specification to product specification: how do we engineer the product to meet these design specifications.

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