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The House of Quality

by John R. Hauser and Don Clausing

Reprint 88307

Harvard Business Review

Digital Equipment, Hewlett-Packard, AT&T, andITT are getting started with it. Ford and GeneralMotors use it–at Ford alone there are more than 50applications. The “house of quality,” the basic de-sign tool of the management approach known asquality function deployment (QFD), originated in1972 at Mitsubishi’s Kobe shipyard site. Toyota andits suppliers then developed it in numerous ways.The house of quality has been used successfully byJapanese manufacturers of consumer electronics,home appliances, clothing, integrated circuits, syn-thetic rubber, construction equipment, and agricul-tural engines. Japanese designers use it for serviceslike swimming schools and retail outlets and evenfor planning apartment layouts.

A set of planning and communication routines,quality function deployment focuses and coordi-nates skills within an organization, first to design,then to manufacture and market goods that cus-

tomers want to purchase and will continue to pur-chase. The foundation of the house of quality is thebelief that products should be designed to reflectcustomers’ desires and tastes–so marketing people,design engineers, and manufacturing staff mustwork closely together from the time a product isfirst conceived.

The house of quality is a kind of conceptual mapthat provides the means for interfunctional plan-ning and communications. People with different

HARVARD BUSINESS REVIEW May-June 1988 Copyright © 1988 by the Presidents and Fellows of Harvard College. All rights reserved.

The House of Quality

John R. Hauser, at the Harvard Business School as a Mar-vin Bower fellow during the current academic year, isprofessor of management science at MIT’s Sloan Schoolof Management. He is the author, with Glen L. Urban, ofDesign & Marketing of New Products (Prentice-Hall,1980). Don Clausing is Bernard M. Gordon Adjunct Pro-fessor of Engineering Innovation and Practice at MIT.Previously he worked for Xerox Corporation. He intro-duced QFD to Ford and its supplier companies in 1984.

by John R. Hauser and Don Clausing

Design is a team effort, but how do marketing andengineering talk to each other?

problems and responsibilities can thrash out designpriorities while referring to patterns of evidence onthe house’s grid.

What’s So Hard About Design David Garvin points out that there are many di-

mensions to what a consumer means by quality andthat it is a major challenge to design products thatsatisfy all of these at once.1 Strategic quality man-agement means more than avoiding repairs for con-sumers. It means that companies learn from cus-tomer experience and reconcile what they wantwith what engineers can reasonably build.

Before the industrial revolution, producers wereclose to their customers. Marketing, engineering, andmanufacturing were integrated – in the same indi-vidual. If a knight wanted armor, he talked directlyto the armorer, who translated the knight’s desiresinto a product. The two might discuss the material– plate rather than chain armor – and details likefluted surfaces for greater bending strength. Thenthe armorer would design the production process.For strength–who knows why?–he cooled the steelplates in the urine of a black goat. As for a produc-tion plan, he arose with the cock’s crow to light theforge fire so that it would be hot enough by midday.

Today’s fiefdoms are mainly inside corporations.Marketing people have their domain, engineerstheirs. Customer surveys will find their way ontodesigners’ desks, and R&D plans reach manufactur-ing engineers. But usually, managerial functions re-main disconnected, producing a costly and demor-

alizing environment in which product quality andthe quality of the production process itself suffer.

Top executives are learning that the use of inter-functional teams benefits design. But if top man-agement could get marketing, designing, and man-ufacturing executives to sit down together, whatshould these people talk about? How could they gettheir meeting off the ground? This is where thehouse of quality comes in.

Consider the location of an emergency brakelever in one American sporty car. Placing it on theleft between the seat and the door solved an engi-neering problem. But it also guaranteed that womenin skirts could not get in and out gracefully. Even if

HOUSE OF QUALITY

4 HARVARD BUSINESS REVIEW May-June 1988

January 1977Pre QFD

April 1984Post QFD(39% of pre QFD costs)

Preproduction costs

Startup costs

EXHIBIT I

Startup and preproduction costs at ToyotaAuto Body before and after QFD

U.S. companyD

esig

n ch

ange

s

EXHIBIT II

Japanese automaker with QFD made fewerchanges than U.S. company without QFD

Japanesecompany

90% oftotal Japanese

changes complete

20–24Months

14–17Months

1–3Months

+3MonthsJob #1

the system were to last a lifetime, would it satisfycustomers?

In contrast, Toyota improved its rust preventionrecord from one of the worst in the world to one ofthe best by coordinating design and production de-cisions to focus on this customer concern. Usingthe house of quality, designers broke down “bodydurability” into 53 items covering everything fromclimate to modes of operation. They obtained cus-tomer evaluations and ran experiments on nearlyevery detail of production, from pump operationto temperature control and coating composition.Decisions on sheet metal details, coating mate-rials, and baking temperatures were all focused onthose aspects of rust prevention most important tocustomers.

1. David A. Garvin, “Competing on the Eight Dimensions of Quality,” HBR November-December 1987, p. 101.

Source for Exhibits I and II: Lawrence P. Sullivan, “Quality FunctionDeployment,” Quality Progress, June 1986, p. 39. © 1986 AmericanSociety for Quality Control. Reprinted by permission.

Today, with marketing tech-niques so much more sophisti-cated than ever before, compa-nies can measure, track, andcompare customers’ perceptionsof products with remarkable ac-curacy; all companies have op-portunities to compete on quali-ty. And costs certainly justify anemphasis on quality design. Bylooking first at customer needs,then designing across corporatefunctions, manufacturers can re-duce prelaunch time and after-launch tinkering.

Exhibit I compares startup andpreproduction costs at ToyotaAuto Body in 1977, before QFD,to those costs in 1984, when QFDwas well under way. House ofquality meetings early on re-duced costs by more than 60%.Exhibit II reinforces this evi-dence by comparing the numberof design changes at a Japanese auto manufacturerusing QFD with changes at a U.S. automaker. TheJapanese design was essentially frozen before thefirst car came off the assembly line, while the U.S.company was still revamping months later.

Building the House There is nothing mysterious about the house of

quality. There is nothing particularly difficultabout it either, but it does require some effort to getused to its conventions. Eventually one’s eye canbounce knowingly around the house as it wouldover a road-map or a navigation chart. We have seensome applications that started with more than 100customer requirements and more than 130 engi-neering considerations. A fraction of one subchart,in this case for the door of an automobile, illus-trates the house’s basic concept well. We’ve repro-duced this subchart portion in the illustration“House of Quality,” and we’ll discuss each sectionstep-by-step.

What do customers want? The house of qualitybegins with the customer, whose requirements arecalled customer attributes (CAs) – phrases cus-tomers use to describe products and product char-acteristics (see Exhibit III). We’ve listed a few here;a typical application would have 30 to 100 CAs. Acar door is “easy to close” or “stays open on a hill”;“doesn’t leak in rain” or allows “no (or little) road

noise.” Some Japanese companies simply placetheir products in public areas and encourage poten-tial customers to examine them, while design teammembers listen and note what people say. Usually,however, more formal market research is called for,via focus groups, in-depth qualitative interviews,and other techniques.

CAs are often grouped into bundles of attributesthat represent an overall customer concern, like“open-close” or “isolation.” The Toyota rust-prevention study used eight levels of bundles to getfrom the total car down to the car body. Usually theproject team groups CAs by consensus, but somecompanies are experimenting with state-of-the-artresearch techniques that derive groupings directlyfrom customers’ responses (and thus avoid argu-ments in team meetings).

CAs are generally reproduced in the customers’own words. Experienced users of the house of quali-ty try to preserve customers’ phrases and evenclichés – knowing that they will be translated si-multaneously by product planners, design engi-neers, manufacturing engineers, and salespeople.Of course, this raises the problem of interpretation:What does a customer really mean by “quiet” or“easy”? Still, designers’ words and inferences maycorrespond even less to customers’ actual viewsand can therefore mislead teams into tackling prob-lems customers consider unimportant.

Not all customers are end users, by the way. CAscan include the demands of regulators (“safe in a

HARVARD BUSINESS REVIEW May-June 1988 5

PRIMARY SECONDARY

Good operationand use

EASY TO OPENAND CLOSE DOOR

Easy to close from outside

Easy to close from inside

Stays open on a hillEasy to open from outside

Easy to open from inside

Doesn‘t kick back

Doesn‘t leak in rain

Doesn‘t leak in car wash

Doesn‘t drip water or snow when openDoesn‘t rattle

Soft, comfortableIn right position

Material won‘t fadeAttractive (nonplastic look)

Easy to cleanNo grease from door

Uniform gaps between matching panels

No wind noise

No road noise

ISOLATION

ARM REST

INTERIOR TRIM

CLEAN

FIT

Good appearance

TERTIARY

EXHIBIT III

Customer attributes and bundles of CAsfor a car door

side collision”), the needs of retailers (“easy to dis-play”), the requirements of vendors (“satisfy assem-bly and service organizations”), and so forth.

Are all preferences equally important? Imagine agood door, one that is easy to close and has powerwindows that operate quickly. There is a problem,however. Rapid operation calls for a bigger motor,which makes the door heavier and, possibly, harderto close. Sometimes a creative solution can be foundthat satisfies all needs. Usually, however, designershave to trade off one benefit against another.

To bring the customer’s voice to such delibera-tions, house of quality measures the relative impor-tance to the customer of all CAs. Weightings arebased on team members’ direct experience with cus-tomers or on surveys. Some innovative businessesare using statistical techniques that allow cus-tomers to state their preferences with respect to ex-isting and hypothetical products. Other companiesuse “revealed preference techniques,” which judgeconsumer tastes by their actions as well as by theirwords–an approach that is more expensive and dif-ficult to perform but yields more accurate answers.(Consumers say that avoiding sugar in cereals is im-portant, but do their actions reflect their claims?)

Weightings are displayed in the house next toeach CA–usually in terms of percentages, a completelist totaling 100% (see Exhibit IV).

Will delivering perceived needs yield a competi-tive advantage? Companies that want to match orexceed their competition must first know wherethey stand relative to it. So on the right side of thehouse, opposite the CAs, we list customer evalua-tions of competitive cars matched to “our own”(see Exhibit V).

Ideally, these evaluations are based on scientificsurveys of customers. If various customer segments

evaluate products differently – luxury vs. economycar buyers, for example – product-planning teammembers get assessments for each segment.

Comparison with the competition, of course, canidentify opportunities for improvement. Take ourcar door, for example. With respect to “stays open ona hill,” every car is weak, so we could gain an advan-tage here. But if we looked at “no road noise” for thesame automobiles, we would see that we alreadyhave an advantage, which is important to maintain.

Marketing professionals will recognize the right-hand side of Exhibit V as a “perceptual map.” Per-ceptual maps based on bundles of CAs are oftenused to identify strategic positioning of a product orproduct line. This section of the house of qualityprovides a natural link from product concept to acompany’s strategic vision.

How can we change the product? The marketingdomain tells us what to do, the engineering domaintells us how to do it. Now we need to describe theproduct in the language of the engineer. Along thetop of the house of quality, the design team liststhose engineering characteristics (ECs) that arelikely to affect one or more of the customer at-tributes (see Exhibit VI). The negative sign on “en-ergy to close door” means engineers hope to reducethe energy required. If a standard engineering char-acteristic affects no CA, it may be redundant to theEC list on the house, or the team may have missed acustomer attribute. A CA unaffected by any EC, onthe other hand, presents opportunities to expand acar’s physical properties.

Any EC may affect more than one CA. The resis-tance of the door seal affects three of the four cus-tomer attributes shown in Exhibit VI – and othersshown later.

Engineering characteristics should describe theproduct in measurable terms and should directly af-fect customer perceptions. The weight of the doorwill be felt by the customer and is therefore a rele-vant EC. By contrast, the thickness of the sheetmetal is a part characteristic that the customer isunlikely to perceive directly. It affects customersonly by influencing the weight of the door and oth-er engineering characteristics, like “resistance todeformation in a crash.”

In many Japanese projects, the interfunctionalteam begins with the CAs and generates measurablecharacteristics for each, like foot-pounds of energyrequired to close the door. Teams should avoid ambi-guity in interpretation of ECs or hasty justification ofcurrent quality control measurement practices. Thisis a time for systematic, patient analysis of eachcharacteristic, for brainstorming. Vagueness will

HOUSE OF QUALITY


BUNDLES CUSTOMER ATTRIBUTESRELATIVE

IMPORTANCE

EXHIBIT IV

Relative-importance weights of customerattributes

EASY TO OPENAND CLOSE DOOR

ISOLATION

Easy to close from outsideStays open on a hill

75

32

Doesn’t leak in rainNo road noise

A complete list totals 100%

eventually yield indifference tothings customers need. Character-istics that are trivial will make theteam lose sight of the overall de-sign and stifle creativity.

How much do engineers influ-ence customer-perceived quali-ties? The interfunctional teamnow fills in the body of the house,the “relationship matrix,” indi-cating how much each engineeringcharacteristic affects each customerattribute. The team seeks consen-sus on these evaluations, basingthem on expert engineering experi-ence, customer responses, andtabulated data from statisticalstudies or controlled experiments.

The team uses numbers or symbols to establishthe strength of these relationships (see Exhibit VII).Any symbols will do; the idea is to choose thosethat work best. Some teams use red symbols for re-lationships based on experiments and statistics andpencil marks for relationships based on judgmentor intuition. Others use numbers from statisticalstudies. In our house, we use check marks for posi-tive and crosses for negative relationships.

Once the team has identified the voice of the cus-tomer and linked it to engineering characteristics,it adds objective measures at the bottom of thehouse beneath the ECs to which they pertain (seeExhibit VIII). When objective measures are known,the team can eventually move to establish targetvalues – ideal new measures for each EC in a re-designed product. If the team did its homeworkwhen it first identified the ECs, tests to measurebenchmark values should be easy to complete. En-gineers determine the relevant units of measure-ment–foot-pounds, decibels, etc.

Incidentally, if customer evaluations of CAs donot correspond to objective measures of related ECs–if, for example, the door requiring the least energyto open is perceived as “hardest to open”–then per-haps the measures are faulty or the car is sufferingfrom an image problem that is skewing consumerperceptions.

How does one engineering change affect othercharacteristics? An engineer’s change of the gear ra-tio on a car window may make the window motorsmaller but the window go up more slowly. And ifthe engineer enlarges or strengthens the mechanism,the door probably will be heavier, harder to open, ormay be less prone to remain open on a slope. Of

course, there might be an entirely new mechanismthat improves all relevant CAs. Engineering is cre-ative solutions and a balancing of objectives.

The house of quality’s distinctive roof matrixhelps engineers specify the various engineering fea-tures that have to be improved collaterally (see Ex-hibit IX). To improve the window motor, you mayhave to improve the hinges, weather stripping, anda range of other ECs.

Sometimes one targeted feature impairs so manyothers that the team decides to leave it alone. Theroof matrix also facilitates necessary engineeringtrade-offs. The foot-pounds of energy needed toclose the door, for example, are shown in negativerelation to “door seal resistance” and “road noisereduction.” In many ways, the roof contains themost critical information for engineers becausethey use it to balance the trade-offs when address-ing customer benefits.

Incidentally, we have been talking so far aboutthe basics, but design teams often want to ruminateon other information. In other words, they custom-build their houses. To the column of CAs, teamsmay add other columns for histories of customercomplaints. To the ECs, a team may add the costs ofservicing these complaints. Some applications adddata from the sales force to the CA list to representstrategic marketing decisions. Or engineers mayadd a row that indicates the degree of technical dif-ficulty, showing in their own terms how hard oreasy it is to make a change.

Some users of the house impute relative weightsto the engineering characteristics. They’ll establishthat the energy needed to close the door is roughlytwice as important to consider as, say, “check forceon 10˚ slope.” By comparing weighted characteris-tics to actual component costs, creative design


BUNDLES CUSTOMER ATTRIBUTESRELATIVE

IMPORTANCE

OUR CAR DOOR

COMPETITOR A’S

COMPETITOR B’S

CUSTOMER PERCEPTIONSWorst 1 2 3 4 5 Best

EXHIBIT V

Customers’ evaluations of competitiveproducts

EASY TO OPENAND CLOSEDOOR

ISOLATION

Easy to close from outside

Stays open on a hill

7

5

3

2

Doesn’t leak in rain

No road noise

teams set priorities for improving components.Such information is particularly important whencost cutting is a goal. (Exhibit X includes rows fortechnical difficulty, imputed importance of ECs,and estimated costs.)

There are no hard-and-fast rules. The symbols,lines, and configurations that work for the particu-lar team are the ones it should use.

Using the HouseHow does the house lead to the bottom line?

There is no cookbook procedure, but the househelps the team to set targets, which are, in fact, en-tered on bottom line of the house. For engineers it is

a way to summarize basic data in usable form. Formarketing executives it represents the customer’svoice. General managers use it to discover strategicopportunities. Indeed, the house encourages all ofthese groups to work together to understand oneanother’s priorities and goals.

The house relieves no one of the responsibility ofmaking tough decisions. It does provide the meansfor all participants to debate priorities.

Let’s run through a couple of hypothetical situa-tions to see how a design team uses the house.n Look at Exhibit X. Notice that our doors aremuch more difficult to close from the outside thanthose on competitors’ cars. We decide to look fur-ther because our marketing data say this customer

HOUSE OF QUALITY


OUR CAR

A’S CAR

B’S CAR

Customer perceptions

1 2 3 4 5CUSTOMERATTRIBUTES

ENG

INEE

RIN

GCH

ARA

CTER

ISTI

CS

OPEN-CLOSEEFFORT

Easy to close from outside 7

• • •• • •• • •• • •• • •• • •

••••••

••••••

5

3

2



No road noise

EASY

TO

OPE

NA

ND

CLO

SE D

OO

R

– En

ergy

to c

lose

doo

r

Rel

ativ

e Im

por

tanc

e

+ C

heck

forc

e on

leve

l gro

und

+ D

oor s

eal r

esist

ance

+ Ro

ad n

oise

redu

ctio

n

ISO

LATI

ON

SEALING-INSULATION

EXHIBIT VI

Engineering characteristics tell how tochange the product

+ C

heck

forc

e on

10°

slo

pe

attribute is important. From the central matrix, thebody of the house, we identify the ECs that affectthis customer attribute: energy to close door, peakclosing force, and door seal resistance. Our engi-neers judge the energy to close the door and thepeak closing force as good candidates for improve-ment together because they are strongly, positivelyrelated to the consumer’s desire to close the dooreasily. They determine to consider all the engineer-ing ramifications of door closing.

Next, in the roof of the house, we identify whichother ECs might be affected by changing the doorclosing energy. Door opening energy and peak clos-

ing force are positively related, but other ECs (checkforce on level ground, door seals, window acoustictransmission, road noise reduction) are bound to bechanged in the process and are negatively related. Itis not an easy decision. But with objective measuresof competitors’ doors, customer perceptions, andconsidering information on cost and technical diffi-culty, we–marketing people, engineers, and top man-agers–decide that the benefits outweigh the costs. Anew door closing target is set for our door–7.5 foot-pounds of energy. This target, noted on the very bot-tom of the house directly below the relevant EC, es-tablishes the goal to have the door “easiest to close.”


OUR CAR

A’S CAR

B’S CAR


1 2 3 4 5

Strong positive

Medium positive

Medium negative

Strong negative

Relationships

CUSTOMERATTRIBUTES

ENG

INEE

RIN

GCH

ARA

CTER

ISTI

CS

OPEN-CLOSEEFFORT


• • •• • •• • •• • •• • •• • •

••••••

••••••

5

3

2



No road noise

EASY

TO

OPE

NA

ND

CLO

SE D

OO

R

– E

nerg

y to

clo

se d

oor

Rel

ativ

e Im

por

tanc

e

+ C

heck

forc

e on

leve

l gro

und

+ D

oor

seal

res

ista

nce

+ R

oad

nois

e re

duct

ion

+ C

heck

forc

e on

10°

slo

pe

ISO

LATI

ON

SEALING-INSULATION

✔

✔✔ ✔

✔

✔

✔

✔

✘

✘

✘

EXHIBIT VII

Relationship matrix shows how engineering decisionsaffect customer perceptions

n Look now at the customer attribute “no roadnoise” and its relationship to the acoustic transmis-sion of the window. The “road noise” CA is onlymildly important to customers, and its relationshipto the specifications of the window is not strong.Window design will help only so much to keepthings quiet. Decreasing the acoustic transmissionusually makes the window heavier. Examining theroof of the house, we see that more weight wouldhave a negative impact on ECs (open-close energy,check forces, etc.) that, in turn, are strongly relatedto CAs the that are more important to the customerthan quiet (“easy to close,” “stays open on a hill”).

Finally, marketing data show that we already dowell on road noise; customers perceive our car asbetter than competitors’.

In this case, the team decides not to tamper withthe window’s transmission of sound. Our targetstays equal to our current acoustic values.

In setting targets, it is worth noting that the teamshould emphasize customer-satisfaction values andnot emphasize tolerances. Do not specify “between6 and 8 foot-pounds,” but rather say, “7.5 foot-pounds.” This may seem a small matter, but it isimportant. The rhetoric of tolerances encouragesdrift toward the least costly end of the specification

HOUSE OF QUALITY


OUR CAR

A’S CAR

B’S CAR


1 2 3 4 5

Strong positive

Medium positive

Medium negative

Strong negative

Relationships

CUSTOMERATTRIBUTES

ENG

INEE

RIN

GCH

ARA

CTER

ISTI

CS

OPEN-CLOSEEFFORT


• • •• • •• • •• • •• • •• • •

••••••

••••••

5

3

2



No road noise

EASY

TO

OPE

NA

ND

CLO

SE D

OO

R

– En

ergy

to c

lose

doo

r

Rel

ativ

e Im

por

tanc

e

+ C

heck

forc

e on

leve

l gro

und

+ D

oor s

eal r

esist

ance

+ R

oad

noise

redu

ctio

n

+ C

heck

forc

e on

10°

slo

pe

ISO

LATI

ON

Obje

ctiv

em

easu

res

SEALING-INSULATION

✔

✔✔ ✔

✔

✔

✔

✔

✘

✘

✘

Our car door

A’s car door

B’s car door

Measurement units ft-lb

11

9

9.5

12

12

11

6

6

7

3

2

2

9

5

6

lb/ftlb lb db

EXHIBIT VIII

Objective measures evaluate competitiveproducts


limit and does not reward designs and componentswhose engineering values closely attain a specificcustomer-satisfaction target.

The Houses BeyondThe principles underlying the house of quality

apply to any effort to establish clear relations be-tween manufacturing functions and customer sat-isfaction that are not easy to visualize. Suppose thatour team decides that doors closing easily is a criti-cal attribute and that a relevant engineering charac-

teristic is closing energy. Setting a target value forclosing energy gives us a goal, but it does not give usa door. To get a door, we need the right parts (frame,sheet metal, weather stripping, hinges, etc.), theright processes to manufacture the parts and assem-ble the product, and the right production plan to getit built.

If our team is truly interfunctional, we can even-tually take the “hows” from our house of qualityand make them the “whats” of another house, onemainly concerned with detailed product design. En-gineering characteristics like foot-pounds of clos-

OUR CAR

A’S CAR

B’S CAR


1 2 3 4 5

Strong positive

Medium positive

Medium negative

Strong negative

Relationships

CUSTOMERATTRIBUTES

ENG

INEE

RIN

GCH

ARA

CTER

ISTI

CS

OPEN-CLOSEEFFORT


• • •• • •• • •• • •• • •• • •

••••••

••••••

5

3

2



No road noise

EASY

TO

OPE

NA

ND

CLO

SE D

OO

R

– En

ergy

to c

lose

doo

r

Rel

ativ

e Im

por

tanc

e

+ C

heck

forc

e on

leve

l gro

und

+ D

oor s

eal r

esist

ance

+ R

oad

noise

redu

ctio

n

+ C

heck

forc

e on

10°

slo

pe

ISO

LATI

ON

Obje

ctiv

em

easu

res

SEALING-INSULATION

✔

✔ ✔

✔✔ ✔

✔

✔

✔

✔

✘

✘

✘✘

✘

✘

Our car door

A’s car door

B’s car door


11

9

9.5

12

12

11

6

6

7

3

2

2

9

5

6

lb/ftlb lb db

EXHIBIT IX

Roof matrix facilities engineeringcreativity


OUR CAR

A’S CAR

B’S CAR


1 2 3 4 5

Strong positive

Medium positive

Medium negative

Strong negative

Relationships

CUSTOMERATTRIBUTES

ENG

INEE

RIN

GCH

ARA

CTER

ISTI

CS

OPEN-CLOSEEFFORT


• • •• • •

••••••

5

3

3

3

2


Easy to open from outside

Doesn’t kick back


No road noise

EASY

TO

OPE

NA

ND

CLO

SE D

OO

R

– En

ergy

to c

lose

doo

r

Rel

ativ

e Im

por

tanc

e

– En

ergy

to o

pen

door

– Pe

ak c

losin

g fo

rce

+ C

heck

forc

e on

leve

l gro

und

+ D

oor s

eal r

esist

ance

+ A

cous

tic tr

ansm

issio

n, w

indo

w

+ R

oad

noise

redu

ctio

n

+ W

ater

resis

tanc

e

+ C

heck

forc

e on

10°

slo

pe

ISO

LATI

ON

Obje

ctiv

em

easu

res

SEALING-INSULATION

✔

✔✔

✔✔✔

✔✔✔ ✔

✔

✔ ✔

✔

✔

✔

✔✔

✔

✔ ✔

✔✔✔

✘

✘✘

✘

✘✘

✘✘

✘

✘

✘

✘

✘

✘

Our car door

A’s car door

B’s car door

Technical difficulty

Imputed importance (%)

Estimated cost (%)

Targets

(all total 100%)

(all total 100%)


ft-lb

11

9

9.5

4

10

57.5

12

12

11

5

6

29

6

6

7

1

4

26

10

9

11

1

9

97.5

18

13

14

3

1

512

3

2

2

1

6

63

.10

.10

.10

3

2

6.10

9

5

6

3

4

99

70

60

60

5

3

270

ft-lb

ft-lb

lb/ft

lb/ ft

lb

lb

lb

lb

lb

lb

db

db

psi

psi

—

EXHIBIT X

House of quality

ing energy can become the rows in a parts deploy-ment house, while parts characteristics– like hingeproperties or the thickness of the weather stripping–become the columns (see Exhibit XI).

This process continues to a third and fourthphase as the “hows” of one stage become the“whats” of the next. Weather-stripping thickness –a “how” in the parts house–becomes a “what” in aprocess planning house. Important process opera-tions, like “rpm of the extruder producing theweather stripping” become the “hows.” In the lastphase, production planning, the key process opera-tions, like “rpm of the extruder,” become the“whats,” and production requirements – knob con-trols, operator training, maintenance – become the“hows.”

These four linked houses implicitly convey thevoice of the customer through to manufacturing. Acontrol knob setting of 3.6 gives an extruder speed

of 100 rpm; this helps give a reproducible diameterfor the weather-stripping bulb, which gives goodsealing without excessive door-closing force. Thisfeature aims to satisfy the customer’s need for a dry,quiet car with an easy-to-close door.

None of this is simple. An elegant idea ultimatelydecays into process, and processes will be con-founding as long as human beings are involved. Butthat is no excuse to hold back. If a technique likehouse of quality can help break down functionalbarriers and encourage teamwork, serious efforts toimplement it will be many times rewarded.

What is also not simple is developing an organi-zation capable of absorbing elegant ideas. The prin-cipal benefit of the house of quality is quality in-house. It gets people thinking in the right directionsand thinking together. For most U.S. companies,this alone amounts to a quiet revolution.Reprint 88307 To place an order, call 800-988-0886.

HOUSE OF QUALITY


EXHIBIT XI

Linked houses convey the customer’s voice through to manufacturing

Engineringcharacteristics

HOUSEOF QUALITY

PARTSDEPLOYMENT

PROCESSPLANNING

PRODUCTIONPLANNING

Cust

om

eratt

ribute

s

I

Partscharacteristics

Engin

eeri

ng

chara

cter

istics

II

Key processoperations

Part

sch

ara

cter

istics

III

Productionrequirements

Key

pro

cess

oper

ations

IV

Source: Modified from a figure supplied by the American Supplier Institute, Inc., Dearborn, Michigan.

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