QFD

Playbook Topic 13 Page 1

Quality Function Deployment

Quality Function Deployment, or QFD, is atool that can help improve your existingprocesses by focusing your energy and yourattention on efforts that will ensure thegreatest result. QFD works by first identi-fying and prioritizing customer require-ments and expectations. (Review Issue 12 ofPlaybook for an introduction to prioritiza-tion matrices.) You then can use this infor-mation to focus with greater confidence onthe important customer requirements as astarting place to define such things as prod-uct requirements, design features, manu-facturing processes or support requirements.

What can it do for you?The payoff of QFD is the creation of morerobust designs and processes that work to-gether to assure customer satisfaction. Anadded benefit is that QFD is able to docu-ment key decisions in a form that can be-come a template for future improvementefforts.

A full-blown application of the QFD disci-pline produces a complex-looking series ofmatrices. In almost all instances, this levelof detail is not necessary. Normally, an ab-breviated version of QFD with only one ortwo matrices is enough to do the job of re-solving a problem, defining Critical ToQuality characteristics (CTQs) or imple-menting actions to reduce costs.

The effort and discipline of QFD producesthe greatest results in situations inwhich customer requirements have not orcannot be sharply defined, those require-ments cannot be met through conventionalprocesses or practices, or the elements ofthe business that must work together to

deliver the requirements have divergent orconflicting goals.

Although QFD is a disciplined tool, it isalso a flexible and adaptable one. ThroughQFD, customer expectations can be logi-cally and practically linked to almost anybusiness process. Virtually any cause-and-effect relationship can be adapted to theQFD discipline.

The application of QFD can range from oneperson constructing a simple matrix to clas-sic Quality Function Deployment in which aformal team generates a systematic flow-down of customer expectations to technicalrequirements, critical part requirements,critical process requirements, and processcontrols. The most practical application ofQFD is usually somewhere between thesetwo strategies.

Quality Function Deployment is especiallyuseful in project bounding and in the meas-ure and improve phases of Six Sigma meth-odology.

How do you do it?1. Define the project.

The first step is to define the project anddescribe the intended results. This willenable you to decide if QFD is the righttool. If the approach is clear, but the re-

quirements are not, or you want toclarify the link between customerrequirements and process require-ments, a simplified QFD might beappropriate.

If the objective is a significantchallenge or there are many con-flicting requirements, a more com-plex QFD is probably a good idea.

PLAYBOOKPLAYBOOKPLAYBOOKSix Sigma PLAYBOOKTopic 13


2. Create the team.The next step is to bring together ateam. List the organizations that have an

interest in or an influence on the re-sult.

Consolidate representation as nec-essary to get the list down to two orthree for a simple QFD or five toeight for a complex one.

Identify team members who repre-sent the defined areas and whowould also have ownership for im-plementing the results.

3. Get buy-in.Make sure you have commitment fromthe proposed team members. If anyone is not interested, find a

suitable replacement. Ensure you have the commitment of

management in each of the inter-ested areas, as well.

Once the team is defined, agree on ateam leader, team ground rules anda regular meeting schedule.

4. Define customer expectations.Think of this as answering the question,What does the customer want orneed? Generate your own ideas through

brainstorming if direct customer in-volvement or surveys are impracti-cal.

Clearly state each expectation as acustomer would perceive it.

Group the expectations into mean-ingful clusters that share a commontheme. Consider creating an affinitydiagram (see Playbook issue 5) witheveryones input.

Although each customer expectationis important, it is necessary to pri-oritize them to help resolve any con-flicts over what to do first. Rateeach customer expectation from 1 to5, with 1 being the least importantand 5 being the most.

Validate your collection of cus-tomer expectations and their relativeimportance by talking with yourcustomer or sources close to yourcustomer.(Always remember, a fundamentalpart of the QFD discipline is to lis-ten to the voice of the customer.)

When you are satisfied with yourlist, transfer your rated customer re-quirements to the left side of yourfirst matrix.

5. Define the requirements that willsatisfy your customers expectations.Think of this as answering the question,How can we meet each customer ex-pectation? Work on each expectation, one at a

time. Remember that you are look-ing for requirements that will causethe customers expectations to besatisfied. (Alternately, you mightuse the discipline to show a cus-tomer why an expectation cannot bemet or to consider what may be pos-sible beyond the customers expec-tation.) You could try brainstormingor create a cause-and-effect diagramto generate requirements.

After you have a list of require-ments, screen them until you haveidentified the critical few. Good re-quirements for QFD are not onlyrelevant, they are also controllableand measurable.

6. Develop the first relationship matrix.This matrix will compare each customerexpectation (the whats) against your listof identified product or service require-ments (the hows). To help decide if the customer

would feel that the product or serv-ice expectation would be met if therequirement were met, ask, If wemeet this product or service re-quirement, would the customer per-ceive this as an improvement insatisfying this need or expectation?


If there would be a perceived im-provement in satisfaction, decide ifthe relationship between meetingthe requirement and improving thecustomers satisfaction is a strongone, a moderate one or a weak one.In your matrix, use a double circleto symbolize a strong relationship, asingle circle for a moderate one, anda triangle for a weak one.

Relationship Matrix

Complete the matrix for all the possi-ble relationships. You should normallyhave at least one strong relationshipunder each requirement. Determiningthe strength of a relationship is a teamjudgment.Here are some tips to help calibratethat judgment to make the most usefulmatrix.

Try to avoid making a matrix thatcontains mostly weak or moderaterelationships.On the other hand, avoid makinga matrix that shows every require-ment related in some way to eachcustomer expectation.A good general rule is that onlyone-third to one-half of the inter-sections in the matrix should havesymbols in them.

7. Check your work.A reality check is usually a good idea atthis point. Ask if the customer would

really be satisfied if you delivered aproduct or service that met your list ofrequirements. Be sure that there are noobvious holes or underrated relation-ships.

8. Prioritize your requirements.When you are satisfied that your matrixis complete and accurate, prioritize therequirements Multiply the strength of each rela-

tionship (1 for weak, 3 for moderateand 9 for strong) times the prioritynumber (1 to 5) for each corre-sponding customer expectation.

Add the results and enter the sumfor each requirement at the bottomof the matrix.

The numeric quantities have no realmeaning, but they do help you to priori-tize the relative importance that meetingeach of the identified requirementswould have in satisfying the package ofidentified customer expectations.

9. Establish targets.Through team discussion, develop targetvalues for the requirements. Take intoaccount whether the goal is to maximizeor minimize a value or condition or tohit a specific target value.

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Pay attention in this step to the effectthat optimizing one requirement has onthe ability of the process to meet theother requirements. Completing the roof matrix that

gives the first matrix the namehouse of quality is the way that thisis done in a formal QFD study. Theroof records correlations betweenthe requirements.

Symbols in the correlation matrixrespond to the question, Wouldmeeting this requirement help orhurt meeting each of the other re-quirements?

The roof matrix is constructed andread diagonally. In our house-of-quality example, reducing weighthas a strong positive correlationwith reducing fuel burn and a strongnegative correlation with increasingthrust.

For simpler QFD projects, formalcorrelation analysis may not be nec-essary. If the team wants to look atcorrelations, it may be enough tocompare the requirements againstone another informallyand note whether optimizing onewould compromise another.

10. Construct the next QFD matrix. The requirements output of the first

matrix is usually used as the input tothe second matrix. The relative im-portance of each requirement fromthe previous matrix would be re-scaled to fit in a 1 to 5 range to keepcalculations easy.

Using the highest priority and mostchallenging requirements as astarting place, the team would gen-erate a list of design features to sat-isfy them.

The other requirements are not forgot-ten. They are often able to be handledby practices other than QFD, however.The team must decide which are the

most important for entry into the secondmatrix to keep the focus sharp. By completing and evaluating this

second matrix in the same way asthe team did the first one, they ar-rive at a prioritized list of designfeatures and Critical To Qualitycharacteristics (CTQs).The matrix scoring helps keep thefocus tied to what is most importantin ultimately satisfying the cus-tomer.

In selecting those most importantCTQs, it is helpful to ask, Is thismeasurable, controllable and rele-vant?

A characteristic should be all threeto be considered as a CTQ.

11. Construct the QFD series of matrices. Using the CTQs as the starting point

for the next matrix, the team shouldapply their understanding of theprocess to create a list of the proc-ess characteristics that must becontrolled to reduce variation in theCTQs.

Fill in the matrix using the samekind of weighting process as youused before. Ask, If we reduce thevariation in this key control charac-teristic (KCC), will the customerperceive this as an improvement?As with CTQs, the selected KCCsmust be measurable, controllableand relevant.

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Completion of this matrix generatesa list of the important process char-acteristics (KCCs) that must receivespecial attention to ensure that de-sign features (CTQs) are met.

The classic form of QFD then con-verts the KCCs into a prioritizedquality plan (process controls) usinga variation of the relationship ma-trix.

Now what?Classic Quality Function Deployment canbe time-consuming and may involve severalteams or teams with shifting membership asthe QFD looks at different processes. In ac-tual application, the QFD tool is usuallymodified, simplified and individually tar-geted to improve a wide range of processchallenges. QFD is not limited to new prod-ucts or services. It can be applied to the im-provement of existing products, services orprocesses as well as for resolving problemsthat affect both external and internal cus-tomers.

Here are some points to ponder about QFD: The process may look simple, but it re-

quires a lot of effort. Many of the results look obviousafter

they are written down. If you dont experience some tough

spots, you probably arent doing it right. The charts are not the objective; they

are only the tool for achieving the ob-jective. Pleasing the end-user is the realobjective.

It is important to use the QFD process tofind ways to succeed in the eyes of thecustomer, not to justify failing to live upto the customers expectations or needs.

Consider using QFD when risks are veryhighsuch as situations involving safety orlarge investmentand it is extremely im-portant to do things right the first time.

You should also consider QFD if: Customers are not satisfied with your

product or service. Your product demands an extensive de-

velopment time. Your customers wants and needs tend

to get lost in the complexity of yourprocess.

Communication has been difficult be-tween the functions responsible for de-livering the product or service to the enduser.

The structure or logic for allocating re-sources is not clear.

The challenges in satisfying customerrequirements appear to be greater thanthe normal processes can handle.

It is a good idea to get help from your areasBlack Belt or Master Black Belt beforestarting a QFD process. If you would like toread about QFD, a good book is The Cus-tomer Driven Company: Managerial Per-spectives on QFD by William E. Eurekaand Nancy E. Ryan (ASI Press, Dearborn,MI, 1988.)

Examples of how these QFD principles havebeen applied at Aircraft Engines can be re-viewed in the QFD Analysis Librarythrough the Netscape Web Browser. (EnterGroups. Select Windows Applications. Se-lect Netscape Navigator. This should putyou on the GEAE home page. Select Qual-ity/Six Sigma. Select QFD Analysis Li-brary.)

1996, The General Electric Company. Playbook is published by GE Aircraft Engines Executive Communication and edited by Janet Grove.For further information or for assistance in using Six Sigma tools contact the Master Belt for your organization.

Documents

QFD