VDA QFD

We would like to thank all the companies and their staff who have contributed to this workgroup: AUDI AG, Ingolstadt BMW AG, Munich Robert Bosch GmbH, Stuttgart Continental AG, Hannover DGQ (Deutsche Gesellschaft für Qualität), Frankfurt Fichtel & Sachs AG, Schweinfurt Ford-Werke AG, Cologne GETRAG Getriebe- und Zahnradfabrik Hermann Hagenmeyer GmbH & Cie, Ludwigsburg Kolbenschmidt AG, Neckarsulm Mercedes Benz AG, Stuttgart Adam Opel AG, Rüsselsheim Dr. Ing. h. c. F. Porsche AG, Stuttgart Siemens AG, Regensburg Steyer-Daimler-Puch AG, Steyer ITT Automotive Europe GmbH, Bietigheim VDO Adolf Schindling AG, Babenhausen Wabco Fahrzeugbremsen, Hannover Volkswagen AG, Wolfsburg Zahnradfabrik Friedrichshafen AG, Friedrichshafen Our thanks also go out to all our readers who have submitted improvement suggestions. Frankfurt/Main, May 1996

VERBAND DER AUTOMOBILINDUSTRIE E. V. (VDA)

VDA-Volume 4: Quality Function Deployment (QFD)

1

Contents

Page

1

Quality Function Deployment (QFD)

3

1.1

Description of the Methods

3

1.2

Case Example (to the end of QT-I)

7

1.3

Quality Table II (QT II)

17

1.4

Quality Table III (QT III)

18

1.5

Quality Table IV (QT IV)

18

2


1

Quality Function Deployment (QFD)

1.1

Description of the Methods

Over time, the tasks in quality assurance have moved away from using testing activities for troubleshooting during production, and shifted towards risk minimization for failure prevention during development and planning. As a result of this development's consistent movement towards the origin of the product creation process, quality assurance must already start during the search for a concept (Figure 1). Product origin

Concept Development

n o i e r t u n l i e a v F e r p

Quality assurance

Product creation

Production planning Production

l e r o t u r l i n a o F c

END

Figure 1

Product Creation and Quality Assurance

The Quality Function Deployment (QFD) method is a comprehensive planning and communication system used for coordinating all of a company's resources, in order to develop, manufacture and market the products and services that the customers expect, so that improvements in the business performance can be brought about by enhancing competitive strength. QFD uses quality tables as its tools, which consist of several matrix fields. These are called Houses of Quality due to their external shape.


3

Internal characteristics characteristics (HOW)

e s e t t n n i a o r a p u g g i n , l s l t e n s i , a l s p e m s o a c C

s r e b t y m i r u i o n r e P n i L

Customer requirements (WHAT)

Customer competitive assessment

t n e r r u C

r o t i t e p m o C

1

2

t e g r a T

3

4

t n e m e r i u q e r r e m o t s u c l a c i t i r C

5

1 2 3 4 5 6

Custo mer

7 8 9 Difficulties in reaching the target (1=easy, 5=hard) Test methods and current and future specification s i Current s y s l c a l t n a i s Target a n r r i e t e v e t i c Competitor t n a i i t r e f a p o h m c o C

5 4 3 2 1

Critical in-house characteristics

ROOF

Weighting

Very positive

Strong

9

Positive

Medium

3

Weak

1

Negative Very negative

Figure 2

4

MATRIX

X X

XX

House of Quality Source: American Supplier Institute, N.Y.


With the help of these quality tables, the "Voice of the Customer'" is translated into the company's language, and the answers to the questions "WHAT" and "HOW" are put in relationship with one another (Figure 3). This is done in four phases (Figure 4).

WHAT ?

? y n W a p O m H o C

Customer

Figure 3

Voice of the Customer and the Company's Language

t c u d o r P

Custom s t r a P

Products s s e c o r P

Parts

Process

Figure 4

s n o i t c u r t s n i k r o W

Consistency from the Customer to the Production Building


5

The first quality table (QT-l) is drawn up during the concept phase; it transfers the customer requirements into in-house characteristics and technical terms. In the development phase, these in-house characteristics are implemented as part characteristics with the help of a second quality table (QT-ll); during the production planning phase, these part characteristics then form the basis for defining the process parameters using a third quality table (QT-lll). In the standardization phase, the fourth quality table (QT-lV) is subsequently drawn up and derives standards for the separate work steps, maintenance instructions and necessary training measures from the process parameters. QFD can be used for services and products, namely during the concept phase for new developments, when deciding on new product generations and for ongoing development of existing products based on the market requirements. The time expenditure for QFD pays off in the long term due to the advantages of -

Customer orientation, Transparency and Team work.

To apply the QFD method, each department and each employee in the company must be simultaneously viewed as an "Internal customer" and "Internal supplier". As a "customer", an employee is delivered an input; he or she produces results in his or her work process and then, as a "supplier", passes the output on to his or her "customers". In the context of this valueadded chain, there is not only a final customer - each organizational unit within the company is also a customer. QFD promises success when the objective throughout the company is to fulfill the requirements of all customers. Correspondingly, the interests of the following internal and external customers must be represented in the QFD team: -

6

Automobile manufacturers (internal and external) Suppliers (external and internal) End consumer (external) Authorities (external)


-

Company employees (internal) in the areas: - Sales - Service - Development - Value analysis - Resource scheduling - Work scheduling - Logistics - Production - Controlling.

An independent company section takes over the moderation; for example, this could be a quality improvement employee. While each team member has a contribution to make during the QT-l phase, the representatives of the external customers, Sales and the Service department can be left out starting with the QT-ll phase. In the QT-lll and QT-lV phases, development also no longer needs to be represented.

1.2

Case Example (to the end of QT-I)

The following sections develop the concept for an ice scraper using the QFD method. This example will attempt to clarify the separate phases and steps in the method. It does not claim to be complete. To draw up the quality table QT-l, the following steps are followed 10 5 1

5a

2,3,4

6,7,8

9

( Figure 5): 1) 2)

Determine and weight the "Voice of the Customer" (customer requirements) Competitive assessment of the "Voice of the Customer" from the


7

3) 4) 5) 5 a) 6) 7) 8)

8

customer's point of view Definition of complaints, guarantee cases and selling points Establish the critical customer requirements Determine the in-house characteristics and ... ... their interactions with the customer requirements Competitive assessment of the in-house characteristics from the company's point of view Compilation of test methods and current and future specifications Assessment of the difficulties in reaching the target


9) 10)

In-house test for working out the critical in-house characteristics Correlations of the critical in-house characteristics with all others. 10 5

1

5a

2,3,4

6,7,8

9

Figure 5

Steps in the House of Quality

Step 1:

Determine and weight the "Voice of the Customer" (customer requirements)

In the first, step, the QFD team puts together the wishes, requirements and needs of all external and internal customers. In this process, expressed and unexpressed (tacitly required) customer expectations and unexpected positive characteristics (innovations) are considered, and then weighted in three levels: (9: very important, 3: important, 1: less important). The aspects of functionality, reliability, producibility, environmental conditions and environmental environmental protection are treated in the House of Quality. In contrast, low costs and high profits are requirements that are generally applicable and that should be considered separately; here, the finished House of Quality - drawn up without financial criteria - is useful when it comes to making decisions, because it makes transparent the possibilities and effects of cost savings and reductions. Step 2:

Competitive assessment of the "Voice of the Customer" from the customer's point of view

The second step is an evaluation, from the customer's point of view, of the degree to which the customer requirements worked out in the first step are met in comparison to the competition. A grade of from 1 (very inadequate) to 5 (very good) is assigned to each separate requirement for both this company and for the best competitor. On the basis of this analysis of the competition, the objective for this company is defined for each requirement


9

in the same grading system. This results in three profiles, line by line, in the corresponding column in the House of Quality: this company's actual status, best competitor, and this company's objective. Step 3:

Definition of the complaints, guarantee cases and selling points

The third step involves gathering information on existing complaints, guarantee cases and selling points for each of the customer requirements. Where applicable, a letter (C = complaint, G = Guarantee case, S = Selling point) and the row number are entered into the column provided in the House of Quality. The complaints, guarantee cases and selling points are then listed in a separate table under the respective letters and line numbers. For example, "C7" would be a complaint that refers to the customer requirement in line 7 of the House of Quality (cf. Figure 6). Step 4:

Establish the critical customer requirements

In the fourth step, the critical customer requirements are marked with stars, on the basis of the assessments worked out from the customer's point of view. Figure 6 shows the first four steps. Step 5:

Determine the in-house characteristics and their interactions with the customer requirements

In the fifth step, at least one in-house characteristic is set for the fulfillment of each customer requirement. Fishbone diagrams and fault tree structures can be helpful for finding ideas and a logical structure. The in-house characteristics that are established are assigned to the columns in the House of Quality. The result is a matrix with the customer requirements in the rows and the in-house characteristics in the columns. The fields in the matrix are filled in on the basis of the question: "Can the customer requirement in the particular line be fulfilled by the in-house characteristic of the associated column 3?”

10


In-House characteristics (HOW) r e b m u t y n i r e i n o r i L P

Customer requirements (WHAT Not permitted to demage vehicle

1

3

Easy to manufacture

2

3

Easy to stow (get out)

3

3

Matches car harmoniously

4

1

Many functions

5

9

6

1

7

9

Functions at ever y temerature

8

3

Fingers should not freeze

9

9 C9, S9

No risk of injury during manufacturing during use

Convenient to use

, s e s s , a t s c i n t n e i e o p a t l g p n a n r i m a l o u l e C g s

No exertion

10

3

Must clear the glass

11

9 G11, S11

Competitive petiti ve assessment of the customer requirements r o t i t t y e a p e d m g r o o a T C T

1 2 3 4 5

s t n e m e r i u q e r r e m o t s u c l a c i t i r C

Weighting Strong Medium Weak

Figure 6

5 3 1

Steps 1 to 4

Table of complaints, guarantee cases and selling points: C9: S9: G11: S11:

Ice that has been scraped off always falls on hands Ice that has been scraped off cannot fall on the hands Ice scraper does not scrape across the entire wide, glass fogs again immediately Pieces of ice are removed immediately from the surface that has been freed of ice (possibly by means of a wiping edge).

A matrix that has been filled out in this way makes it easy to see the significance that the separate in-house characteristics have for the fulfillment of the customer requirements (Figure 7). very good good not as good not at all

= = = =

no entry.


11

Figure 7

12

Step 5


Step 6:

Competitive assessment of the in-house characteristics from the company's point of view

In the sixth step, the in-house characteristics are evaluated in the competitive comparison in a procedure similar to the one used in the second step. The result is again three profiles with grades from 1 (very inadequate) to 5 (very good): this company today, best competitor, objective. Step 7:

Compilation of test methods and current and future specifications

In the seventh step, test methods and current and future specifications are compiled for all in-house characteristics. This is done by entering the following in the line provided in the House of Quality: T1, T2, T3, etc., for test methods, C1, C2, C3, etc., for current specifications and F1, F2, F3, etc., for future specifications, each in the appropriate column. On a separate sheet, the separate definitions are described in greater detail under the corresponding identification (cf. Figure 8). 8).


13

List of the test methods and current and future specifications: T1: Hardness Hardnes s test C1: Plastic Pla stic indentation hardness 84 N/mm² rubber hardness Shore A70, Z1: =C1, etc. Figure 8

14

Steps 6 to 8


Step 8:

Assessment of the difficulties in reaching the target

In the eighth step, the difficulty in reaching the objective is ranked for each in-house characteristic, in steps from 1 (easy) to 5 (difficult). Steps 6 to 8 are shown in Figure 8. Step 9:

In-house test for working out the critical in-house characteristics

In the ninth step (Figure (Figure 9) 9) it is time to "read" from the House of Quality, which is now completely filled in. This checks whether the assessments made from the customer point of view in the horizontal harmonize with the weighting from the company point of view in the vertical. If this is not the case, the corresponding corrections must be made in the House of Quality. Then the critical in-house characteristics are marked with stars.


15

Figure 9

16

Step 9


Step 10:

Correlations of the critical in-house characteristics with all others

Figure 10

Step 10, House of Quality, Completely Filled In.


17

In the tenth and last step (Figure 10) in the QT-I phase, the roof is added to the House of Quality. Appropriate symbols are used to identify how the critical in-house characteristics correlate with the other in-house characteristics. This completes the QT-I phase. Parallel to the processing of the other QFD phases, the knowledge gained in the QT-I phase is already used for other activities, such as risk analyses (FMEA, FTA), experiment design (DoE) and SPC preparation (Figure 11).

QFD

Figure 11 1.3

Critical characteristics

Unclear correlations

Risk analyses

DoE

Characteristics relevant to customer

SPC

QFD as the foundation for further methods Quality Table II (QT II)

Assemblies and part planning (Phase 2) The critical in-house product characteristics worked out in quality table ta ble I (QT 1) are the basis for the additional procedures in phase 2. The product characteristics are now the "WHAT" requirements, and the "HOW" constructions (design solutions) must be worked out for them. This "What - How" quality table table is evaluate evaluated d as described described in step ste p 5 of phase 1. Critical characteristics that are detected here undergo further treatment in phase 3.

18


1.4

Quality Table III (QT III)

Process planning (phase 3) The critical assemblies and part character characterist istics ics are included again as "What" requirements and the "How" constructions (process solutions) are worked out in the quality tables. This "What - How" quality table is evaluated as described in step 5 of phase 1. Critical processes that are detected here undergo further treatment in phase 4.

1.5

Quality Table IV (QT IV)

Work instruction planning (phase 4) The last quality table to be drawn up in this chain has the critical processes as its "What" requirements. The "How" constructions (work instructions) are worked out here. This quality table is evaluated as described in step 5 of phase 1.


19

Bibliography |1|

Rolf Blank:

Qualitätsdenken fängt bei Kunden an! (Presentation manuscript, Kodak AG)

|2|

Jürgen Ebeling:

Qualität auf neuen Wegen (BMW brochure)

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VDA QFD

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