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A case study in solving customer complaints based onthe 8Ds method and Kano modelHsiang-Ru Chen & Bor-Wen Cheng

a a

aDepartment of Industrial Engineering and Management, National Yunlin University of

Science and Technology, 123 University Road, Section 3, Douliou, Yunlin 64002, Taiwan,Republic of ChinaVersion of record first published: 14 Jun 2010.

To cite this article:Hsiang-Ru Chen & Bor-Wen Cheng (2010): A case study in solving customer complaints based on the8Ds method and Kano model, Journal of the Chinese Institute of Industrial Engineers, 27:5, 339-350

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Journal of the Chinese Institute of Industrial EngineersVol. 27, No. 5, September 2010, 339–350

Acasestudyinsolvingcustomercomplaintsbasedonthe8DsmethodandKanomodel

Hsiang-Ru Chen and Bor-Wen Cheng*

Department of Industrial Engineering and Management, National Yunlin University of Science and Technology,123University Road, Section 3, Douliou, Yunlin 64002, Taiwan, Republic of China

(Received August 2008; revised September 2009; accepted April 2010)

Service economics is growing in importance, and satisfying customers is a major objective of enterprises. Product or service quality involves knowing what the customers’ needs are and how tofulfill those needs to meet their expectations and requirements, especially when customer complaintsappear. In this study, the Kano model is used to distinguish various product and service satisfactionordissatisfactiontypes,basedoncustomers’opinions.The8disciplines(8Ds)problem-solvingmethodisacorrectiveactionprocedureusedtoidentifyandcorrectcausesofnon-conformanceandisadoptedin this article when the customer complains about a product or service. A case study in this articleisbasedonthe8DsmethodandKanomodel,whichprovidesastructuredandflexibleframeworkfor

acustomer-orientedmanagementsystemtodrivetheimprovementofbusinessperformance.Bywayof differenthistogramcomparisons,apairedt test,andCpkestimations,acontrolmodelisestablishedtoidentifywhatthequalitylevelis.Aftercompletingthecorrectiveactionsandexcludingthevariationof sheet metal hardness factor, the defect rate decreased from 28% to 0.5%, and this improvementresulted in gains of at least 22 million New Taiwan dollars.

Keywords:customer complaints; 8Ds; problem-solving method; Kano model; ISO/TS 16949

1. Introduction

Aspiring to satisfy the customer is the objective of

enterprise. Service quality involves acknowledging

customers’ needs and fulfilling their expectations

and requirements, especially when customer com-plaints appear.Kanoetal.[8]revisedthe‘‘Motivation-Hygiene

Theory’’ofHerzbergetal. [7]toclassifyandshow

distincttypesofqualitythathavedifferentimpacts

on satisfaction in product or service development

and improvement. Deming [5] argued from the

consumer’s standpoint that product qualities are

determined by three crucial factors: the first is the

product itself; the second is the satisfaction cogni-

tion of consumer or user while using the product;

andthethirdistheoperationmanual,instructions,

and maintenance and after-sales service. If any of the above fails, complaints will arise. The International standard, ISO 9001:2008,

promotes the adoption of a process approach

when developing, implementing, and improving

theeffectivenessofaqualitymanagementsystemto

enhancecustomersatisfactionbymeetingcustomer

requirements. The process approach emphasizes the impor-

tance of understanding and meeting requirements,

the need to consider processes in terms of added

value, obtaining results of process performance

and effectiveness, and continual improvement of processes based on objective measurement.

ISO/TS 16949:2009 is a technical specificationwhich, in conjunction with ISO 9001:2008, defines

the quality managementsystemrequirementsfor the design and development, production whenrelevant, installation, and service of automotive-related products.

The ISO/TS 16949 quality system respectscustomer orientations, originally from the cus-tomer’sneedsandrequirements,and,bymeasuringcustomer satisfaction and deficiencies correctedat the end, so pay attention to the complaints of customers and make some efforts to analyze andcorrect the dissatisfaction reasons and thus buildup customer loyalty.

The8disciplines(8Ds)methodisatoolofISO/ TS 16949:2009 and has been widely applied inautomotiveindustriesfor service or productsproblem solving, including the problems withsupplier qualification confirmation, manufacturingprocess deviations, defects, maintenance, customercomplaints, returned purchases, etc. The purposeof this article is to use the 8Ds method to solvecustomer complaints and make the quality of service robust in order to please customers andprovide excellent service.

*Corresponding author. Email: [email protected]

ISSN 1017–0669 print/ISSN 2151–7606 online

2010Chinese Institute of Industrial Engineers

DOI: 10.1080/10170669.2010.495508

http://www.informaworld.com

wnloaded by [University of Mysore ] at 23:39 10 January 2013



The 8Ds is one of the many approaches toproblem solving, and it depends on the natureof the problem and who the people involved are.It then integrates different histogram comparisonsand process capability index (Cpk) estimations tohelp make correct decisions and take correct

actions. Corrective actions in 8Ds are mostlydealing with quality improvement through statisti-calprocess control and analyzingwhenthequalityis out of control or does not meet the customer’srequirements.

Organizations must stop using the ‘‘goalpost’’approach and instead use the statistic controlprocess that defines quality requirements in termsof the distribution about the target value toimprove customer satisfaction.

A case study in this article is based on the 8Dsmethod and Kano model, which provides a

structured and flexible framework for a customer-focused managementsystem to drive theimprovement of business performance.

2. Research issues and hypotheses

2.1 Kano model

The Kano model has been widely applied in manykinds of goods or service industries and canintegrate quality function deployments, failuremodes, and effects evaluation to set up qualityattributes and focus priorities to satisfy customerexpectationsand raise customer satisfaction[1,4,9,10,13].

Which product characteristics will affect satis-faction? Which attributes, from the customer’sviewpoint, must be fulfilled? What level of goods

and services should be attained to meet customer

satisfaction? The voice of the customer providesthe direct information and requests regarding hisor her product and service demands.

Conventionally, some scholars assumed thatthere existed a linear relationship between product

(or service performance) and customer satisfaction[2,3,14]. However, there are times when additional

efforts cannot increasecustomersatisfaction.Progress depends on the ‘‘type’’ of customer

expectations [11].Kano et al. [8] revised the motivator–hygiene

(M–H)theoryanddevelopedatwo-waymodelthat

distinguishes between different quality attributetypes. Zhang and Von Dran [15] argued that

‘‘hygiene features’’ are those that are necessarybut insufficient to ensure user satisfaction. This

study divides quality attributes into five distinct

categories as follows and as shown in Figure 1.

(1) Attractive quality: this attribute has thegreatest influence on how to satisfy cus-

tomerrequirementsiftheattributesarepre-sent and satisfactory attractiveness can

make a product or service superior to thatof competitors.

(2) One-dimensional quality: traditionally, this

attribute is positively and linearly relatedto customer satisfaction. Heightening the

degree of fulfillment of this attribute willraise the degree of customer satisfaction. Therefore, in Kano’s model, the customerreaction depends linearly on the level of

fulfillment only for one-dimensionalrequirements.

Figure 1. Kano model.

340 H.-R. Chen and B.-W. Cheng




(3) Must-be quality: the customer takes must-be requirements for granted, and the must-be requirements are essential functions of any product or service. Fulfilling the must-be requirements will only lead to a state of ‘‘dissatisfaction’’; if must-be requirements

are not present, the customers will beextremely dissatisfied. However, the fulfill-ment of this attribute does not increasesatisfaction since customers look at it asfundamental.

(4) Indifferent quality: this is an attribute inwhich the quality or absence of qualitydoes not affect customer satisfaction; thus,there is little need to pay attention to thisattribute.

(5) Reverse quality: an attribute whose pres-ence causes customer dissatisfaction and

whose absence results in customersatisfaction.

Various distinct types of satisfaction or dissat-isfaction depend on whether certain customerneeds are completely fulfilled. Therefore, goodsor service suppliers must understand the qualitycategories and develop them so as to be morevaluable, even though Kano’s model has limita-tions of usage and is mostly used for analyzingthe effects of and certainly not for suggesting newproduct features [1].

2.2 8Ds problem-solving method

The concepts of the 8Ds problem-solving methodcanbetracedbacktoUSMilitaryStandard(MIL-STD)1520C[12].Thepurposeofthisstandardsetsforth the requirements for cost-effective correctiveactionanddispositionsystemsfornon-conformingmaterial; so, the primary purposes of a correctiveaction and disposition system are to identify andcorrectthecausesofnon-conformance,preventtherecurrence of wasteful non-conforming material,performance, and quality that reduce the cost of

manufacturing inefficiency, and foster quality andproductivity improvement. TheFordCompany,accordingtotheessenceof

MIL-STD1520C,developedthemethodof‘‘8Ds,’’which defined the problem and collected data orinformation at the beginning, then systematicallyanalyzedthecausesandeffects,andthensolvedtheproblem and prevented future occurrences [6].

The 8Ds problem-solving method is a team-oriented problem-solving organization, andshouldbebased onthetruthand focusedonhowto meetthe requirements of customers.

The 8Ds are most effective in dealing with

long-term problems, primary defects, purchaseorder returns, and cost down and safety issues.

Thesefactorssetupnotonlyaprocedurebutalsoacompletereporttobeabletoverifyactionsaftertheproblem is solved, and can provide support foraknowledgebasethatcanacceleratethesolvingof similar problems and be capable of training thewholeteamtopreventthesameproblemrecurring.

The contents of the 8Ds are as follows:

D1. Team approach: A cross-functional team isorganizedintoasystemtodealwithcustomercomplaints or quality deviations during theproblem solving period.

D2. Describe the problem: This step is to under-stand the problem that affects the quality orcustomer requirements and the causes thatinfluence it.

D3. Develop an interim containmentaction:Because the team is composed of competentmembers, possible reaction activities shouldbe undertaken to control and avoid expan-sion. The team members should define andimplementthoseintermediateactionsthatwillprotect the customer from the problem untilpermanent corrective action is implemented.Interim containment action should follow theISO/TS 16949:2008 quality systemanddepends on the actual approach to make adecisionandverifywithdatatheeffectivenessoftheseactionsappropriately.Thepurposeof this step is to preserve some kind of evidenceand to avoid the outcome from being irreme-

diably enlarged before the problem can besolved and the goal achieved. Documenting,control planning, scheduling, and assigningneeds to track should be done to help ensurecompliance with requirements.

D4. Defineandverifyrootcauses:Tofindtherootcauseofaproblem,weusethe5W2Hmethodto diagram customer requirements, to reviewthe process, and to analyze the problem.

D5. Choose/verify permanent corrective actions:Depending ondifferent kindsof causes, somecorrespondingstrategiesareproposed.Results

are then checked and adjustments made, orsomepermanentcorrectiveactionistaken.D6. Implement and validatecorrectiveactions:

Corrective actions are taken to assure thatthe target is attained and the problem issolved.

D7. Prevent recurrence: Precautionary measuresare set up to avoid similar problems withdefects.

D8. Recognize team and individual contributions:Allteammembersaregivenpositivefeedback. Training and education records are main-tained. The Plan-Do-Check-Act (PDCA)

cycle is followed to attain higher customersatisfaction.

Journal of the Chinese Institute of Industrial Engineers 341




The8Dsareaneffectivemethodtofindoutthe

root causes ofproblems, and members intheteamcan follow aregular procedureto determine whichcorrective actions are appropriate to avoid future

recurrencesforproactivequalityassurancedecisionmaking.

3. Case study

3.1 Source

3.1.1Sample and procedure

There is a customer complaint concerning theperformance quality of dry wall screws (shown in

Figure 2). Dry wall screws are a kind of thread-forming tapping screws which do not need a pre-

drilled hole before penetrating to join two sheet

metals with the thread extruding the material andthe female thread forming, but not cutting.In this study, a manufacturer makes approxi-

mately 30 billion pieces with a value of 80 million

dollars per year. The defect rate is approximately28% and causessubstantialmonetarylosses.Defects result in extra reworking as well asdamage to the reputation of the manufacturer.

The high defect rate results in extra labor costs

and customer dissatisfactionfor the screw

manufacturer.ADclientisthelargest customerofthestudied

company. The customer argued that the quality

of the product did not meet its requirements, suchas drive speed time, force, and dimensions; and

even though they extended the acceptable qualitylevel and specification criteria many times, still the

manufacturer failed to improve quality, and cus-tomers demanded refunds and/or lower prices and

the manufacturer lost market share. The customerrequested that all correction actions should be

recorded and the 8Ds reports should be submitteduntil the case was closed.

Therearesomerequirementsofdrywallscrews

that the customer requested which take them into

Kano’s distinct categories.They include thefollowing.

3.1.1.1Quality of product

(1) Functions:

The functions of mechanical properties includethe hardness, the torque strength, that rust resis-tancemustfittheminimumrequirements,andthat

the maximum drive speed time must be 0.6s.

(2) Easy to use:

When drilled into sheet metal, the productshould,innormalpractice,beeasytousewithlightforce.

(3) Dimension stabilization:

Alldimensionsshouldbeinaccordancewiththedrawings provided by the customer.

3.1.1.2Delivery.Products should be delivered ontime to the designated locations requested by thecustomer.

3.1.1.3Communication.A major sales representa-tive should be provided for good communicationand to deal with all the details.

3.1.1.4Documentation.All the documents shouldbe established in accordance with the documentcontrol procedures of the ISO 9001:2008 quality

system, which includes inspection reports, draw-ings, control plans, etc.

3.1.1.5Packing. The packaging and carton stylesneed to comply with customer indication andduring shipment must protect the product fromdamage.

3.1.1.6Price competitiveness.Price should bedetermined by both supplier and customer andcannot be changed by one side. However, the

supplierneedstoreducecostscontinuouslyinorderto help the customer enlarge its market share.

3.1.1.7Without return or get a refund(responsibilities).When products are delivered tothecustomerandflawsdiscoveredsothattheyfailto meet quality requirements, all products shouldbediscardedatthedeliverypointwithoutobjectionor asking for products to be returned. The proce-dure included four steps in this study (shown inFigure 3).

8Ds must be used to correct and improve

the quality attributes. The attractiveness and one-dimensional qualities, which based on fairness,Figure 2. Dry wall screws.





are not good, should be in the satisfaction inves-tigation form.

3.2 Apparatus

3.2.1Drive speed test machine

A drive speed test machine is shown in Figure 4.It is used to count the time in seconds taken toscrew into the sheet metal. The load force was setat four levels as follows: 10.2, 11, 12, and 14kgin order to make a comparison of performance.

3.2.2Particle image velocimetry

Aparticleimagevelocimetry(PIV)systemisshownin Figure 5. It provides two- or three-dimensionalvelocity maps in flows based on imaging by smallparticlesintheflow,illuminatedbyalaserlightand

via flow visualization and measurement to analyzesmall particle flow. A PIV was used in this studywithhigh-speedphotographytohelpusunderstandhowthethreadpenetratesintothesheetmetalandto assist with our analysis of defective dry wallscrews.

The specifications of the apparatus are asfollows:

(1) Laser type – infrared lasers(2) Wavelength – 808nm (red)(3) Charge-coupled device: full resolution –

512 512pixels

(4) Maximum frame rate – 5145fps.

3.3 Statistical analysis

Minitab 14.0 statistical software was selected asthe tool for data analyses. A histogram and Cpkwas used to compare and illustrate the pre- and

Quality does not

steadily meet the

specification and it

causes customer

complaints

Inspection

Process

Heat treatment

Tools

Too few samples

to judge

Rolling die is failured

Slight invisible

defects occurred

Without lubrication

Violate the SOP

Wrong core hardness

and

surface hardness

Timekeeper found inconsistencies

based on different decimal places

Carburized depth

is not enough

Quality does not

meet specifications

causing customer complaints

Figure 5. Cause and effect diagram.

Investigate customer satisfaction

requirements and classify them into Kano

model attributes.

8Ds must be used to correct and improve the quality attributes.

The attractiveness and one-dimensional qualities, which based onfairness, are not good, should be in the satisfaction investigation

form.

Search for root causes of the problems,

and verify by comparing the Cpk prior to

and after correction.

Announce preventative actions and trace

customer satisfaction.

Figure 3. Case study procedure.

Figure 4. Drive speed test machine.





post-correctiveactionresultsandverifywhetherthe

improvement had been achieved.Cpk is an index which measures how close a

process is running to its target without deviating

from the specification limitation relative to thenatural variability of the process.

4. Results

Thesatisfactioninvestigationwasdistributedtothecustomer and completed according to the cus-tomer’s perceptions when it was argued thatproduct quality was not good enough. All theevaluation items were evaluated using the cus-tomer’sopinionswithoutanyinterferenceandthen

sent back to the case company immediately. Thecustomer satisfaction investigation was classified

into Kano model categories (shown in Table 1).Accordingtotheresults(showninTable1),we

focusedontheevaluationitemsthatare‘‘must-be’’,‘‘attractive’’,‘‘one-dimensional’’,and ‘‘reversequality’’ categories, and on which evaluations

were ‘‘not good’’ or ‘‘very bad’’. The qualityinvestigation into the dry wall screws came from

the customer and causes for the complaints wereanalyzed and solved by the 8Ds solving method.

The 8Ds problem-solving method was devel-oped as follows.

4.1 Discipline 1

4.1.1 Team approach

Inthis stage, the casecompany established asmallgroup of people with appropriate knowledge,authority, and skill to solve the problem andimplement corrective actions. The group includedsome departments and the team leader was theR&D manager. The quality improvement projectwas called the ‘‘Kano quality study’’ and is shownin Table 2.

4.2 Discipline 2

4.2.1Describe the problem

The customer received some complaints fromtheirend users and they had voiced much discontentwith the product over the past 3 months. Thecustomerhaddoubtsconcerningpossibledefectsin

Table 1. Customer satisfaction investigation.

Evaluation item Excellent Good Fair Not good Very bad

1.Quality productsFunction (required)

a?

Easy to useb

?Dimension stabilization

c?

2.Delivery (on time)a

?3.Communication

b?

4.Documentationa

?5.Packing

a?

6.Price competitivenessb

?7.Without return or get a refund

d?

Notes: Must-be quality.a

bAttractive quality.cOne-dimensional quality.dReverse quality.

Table 2. Kano quality study.

D1 Team approach

The source of the Specificationproblem The product of M4.221mm dry wall screws from American

airlines (AA) customerProject title Kano quality study – customer complaints improvementLeader R&D managerDescription 1.Establish a cross-functional group

2. Integrate resources3.Highlight the objective

4.Solve customer complaints5.Study the preventive measures





the products, with causes such as the materialsources, thread die accuracy and thread formingshape, heat treatment processes, etc., harming thestructure’ssafetyandrequiringharderworkduringoperation.

This case company gathered the customer’s

feedback and user reports from the satisfactioninvestigationandwasaskedtoprovidenotonlyanimprovement report, but also to correct the prob-lem completely.

Thecompanyprovidedproductsandinspectionreports to the customer. Although the qualityreports showed all products fitting the specifica-tions,thecustomerconsideredthesamplingreportsto be not presenting the actual qualityperformance.

4.3 Discipline 34.3.1Develop an interim containment action

In this stage, the team proposed interim contain-ment actions (shown in Table 3).

4.4 Discipline 4

4.4.1Define and verify root causes

Some items that might influence the quality per-formance were proposed (see the cause and effectdiagram in Figure 5) and the real causes were

checked and marked. The major root causes are as follows:

(1) About the tool

After a long period of working, the rolling diedeveloped someslightinvisibledefects,resultinginthe shape of the thread not being satiated andhollowed (Figures 6 and 7).

Thetimekeepersusedbythecasecompanyand

thecustomer measuredtimeinconsistently because

differentnumbers ofdecimalplaceswereused,e.g.0.1and 0.01s.

(2) About inspections

The sample size was not large enough todetermine whether the performance of the product

lots was qualified and steady or not. The case companyoverexpandedthe test

specificationconditions,which decreasedthe

Table 3. Interim containment actions.

Interim containment action Measurements Responsibility/Date

1. Breakoffmanufacturingandcheckdiesandtools. No problem was found Manufacture departmentXX-XX-20082. Check the process and parameters, if they

aremissedthenputthemrighttothewaywhere they were set.

No problem was found R&D DepartmentXX-XX-2008

3. Increaseinspectionfromonetothreetimes.After increasing the samplingfrequency some inspectingresults deviate the specifica-tion.Warning!

Quality assurance departmentXX-XX-2008Suggestions:Needtocheckthe

causes and improve4. Record the quality performance Present the inspection data

visualize and save it intoMinitab worksheet.

R&D departmentXX-XX-2008

5. Distinguish certificated and un-certificatedproducts

Setupdifferentstorageregionsandmarkthemindividually.

Plant management departmentXX-XX-2008

6. Develop an analysis and correction planCompile all the information of

products and take them toanalyze.

Team

XX-XX-2008

Figure 6. Two different tiny defects appeared on thesurface of the thread.

Figure 7. Abnormal discontinuous shatter.





supplier’s returned goods rate but neglected thecustomer’s real expectations.

4.5 Discipline 5

4.5.1Choose/verify permanent corrective action

Therearefourrootcausestobedefined;eachcause

for the problem needs to have a correspondingcorrective action taken and the action should beverified. The result of corrective actions andverifications are illustrated in Table 4.

Because of the different decimal timekeepersused, two different drive speedtime resultsappeared(showninTable5).Whenthetimekeepermeasured the times and rounded them to twodecimal places, the average speed time was 0.447sand there were two samples that exceeded thespecifications. When the timekeeper counted thetimesandroundedtoonedecimalplace,theaverage

speed time was 0.396s and all samples qualified. These different results will cause either acceptanceor rejection of the product.

In this study, 25 dry wall screw pieces withworse threads and 25 pieces with betterthreads were sampled randomly again to compareusing different load forces. The comparisonsof Cpk are shown in Table 6, which showsthat the Cpk of the better thread of dry wallscrewsishigherthan1.67withdifferentloads.Theresults show that the better thread can workin practice with labor-saving and engineeringreliability.

The histogramof skewnessand kurtosismeasurement of the drive speed test is shown in

Figure 8 and shows that the better threads of drywall screws have the superior performance.

In this article, the pairedt test showed thatdifferentloadsandworseandbetterthreadsallaresignificant (Table 7).

4.6 Discipline 6

4.6.1Implement and validate corrective actions

We followed D5 and implementedcorrective

actions, which had been validated, and continuedchecking the performance of the following lot of

production. Every action needed to be recorded

andthedocumentshadtoberevisedresponsiblybycertain people and by certain dates.

Table 4. Choose/verify permanent corrective action.

Root causes Corrective action Verification of action

1. The rolling die shows someslight invisible defects.

Setupthelifeexpectancyandsorttherolling die after producing certainquantities. Lookover andconfirm

the shapes of threads are alwaysfine with optical electronmicroscope.

The inspection report shows thedimensions are qualified.

2. The timekeeper reckoned thetime between the casecompany and customer wasinconsistent because of different decimal places.

Set up timekeeper to two decimals(0.01sec scale) and correspondingwith customer drive speed testmachine.

After the modification we comparedthe drive speed test time, and wefound there were significantdifferences and shown in Table 5.

3. Sample size is too small todetermine the productperformance.

Besides batch sampling, use Cpk tomeasure how closer the process isrunning to its target.

Effectively. The Cpk ofbetter threadishigherthantheworsethreadandtheresultsareinshowninTable6.

4. Overexpanding the load from10.2to 14kgf levels butneglecting the customers’real expectations.

Compare the performance withdifferent loads and narrowedspecification width as a controllimit.

From the histogram in Figure 9, theload of 12kgf, it clearly shows theability and elasticity to deal withcustomers respect. Pairt test

between loads are all significantand shown in Table 7.

Table 5. Drive speed time at different numbers of decimal places.

14kg (rounded down to two decimal places, in 0.01s)

0.42 0.39 0.37 0.36 0.350.47 0.48 0.57 0.43 0.440.45 0.54 0.42 0.42 0.53

0.35 0.38 0.37 0.39 0.460.44 0.43 0.62 0.44 0.65

14kg (rounded down to two decimal place in 0.1s)0.4 0.3 0.3 0.3 0.30.4 0.4 0.5 0.4 0.40.4 0.5 0.4 0.4 0.50.3 0.3 0.3 0.3 0.40.4 0.4 0.6 0.4 0.6





When all the corrective actions were taken, the

questionnaire on customer satisfaction was sent toreconfirm whether the improvementsweresatisfactory.

First of all, the product quality requirementsinclude‘‘mechanicalfunctions,’’‘‘easytouse,’’and‘‘dimension stabilization’’. When the causes of

defects are realized and solved for the products,then the production line can robustly yield withconfidence.Second, the productionplan andschedulewillkeepupwiththedeliverytimewithoutusing air freight to ship to the customer and withless disagreement in communication. Due to theincrease in quality and absence of any need torework or scrap the product, the cost will reduce,which will reflect on the sales price and enhancecompetitiveness.

Mostoftheevaluationitems,afterthecustomerhad reviewed the samples and reports, showed

that the quality had greatly increased and nowthe product was listed in the good or excellentcategory (Table 8).

4.7 Discipline 7

4.7.1Prevent recurrence

In this step, any failures or defects should be

completely identified; corrections should bedescribedas a systematic group of activities

intendedto:(1)recognizeandevaluate;(2)identifyactionsthatcouldeliminateorreducethechanceof them reoccurring; and (3) document the entirestandard of the process into a drawing and stan-dards. It is important to not only emphasize theproduct and process, but also to understand that

education and more training are essential toprevent the problem from recurring again.

Figure 8. Results of histogram of different loads.

Table 7. Results of pairedt test.

Item N SD difference SE mean difference t-value p-value

14kg(w)–14kg(b) 25 0.051 0.010 8.17 0.000*12kg(w)–12kg(b) 25 0.050 0.010 9.44 0.000*11kg(w)–11kg(b) 25 0.081 0.016 5.81 0.000*10.2kg(w)–10.2kg(b) 25 0.088 0.018 6.26 0.000*

Note: *Significant.

Table 6. Cpk with different loads.

Screw The thread is worse The thread is better

Load (kg) 14 12 11 10.2 14 12 11 10.2Cpk 0.90 0.68 0.38 0.14 2.56 2.43 2.23 1.83





4.8 Discipline 8

4.8.1Recognizeteamandindividualcontributions

With total quality management development, all

members are needed to be involved in the entireorganization of quality control and be responsibleforthesocialdutiesoftheprocessand/orproduct.Although each company has its own individual

culture, the conscientious participation of teammembers will increase the quality continuously.

5. Conclusion and discussion

Overthepastyears,theapproachpresentedinthisarticle has been thoroughly applied on all tier

suppliers in the automotive industry and thefeedback received from the suppliers has beenvery positive. Again, these methods proved to beveryeffectiveinexplaininghow8DsandtheKano

modelwork,andhowtheycanbeusedandappliedontheshopfloorasapowerfultoolforimproving

quality and customer satisfaction. This study shows that there are three major

factors thataffectedqualityperformance.Thefirstis the different test loads: the heavy load gains the

better outcome in speed time, but it means thatmore force is needed in practice, which is inconve-nient for users. The second is that timekeeper

discrimination should be consistent and accurateaccording to customer requests. Finally, the screw

should have a full thread in the threading processand enable it to be used without extra resistance.

In this study, the Kano model was a good andsimplemethodincompliancewithcustomerrecog-

nition to help the company put emphasis on themost important thing.The 8Dscandistinguishthe

root causes and provide appropriate actions inproblem solving and prevention.

A case study in this article is based on the 8Dsmethod and Kano model, which provide a struc-tured and flexible framework for a customer-focused management system to drive the improve-ment of business performance. After completingthecorrectiveactions,andexcludingthevariationsin sheet metal hardness factor, the defect ratedecreased from 28% to 0.5%, and this improve-ment resulted in gains of at least New Taiwan 22million dollars.

Although the method applied has an excellentresult in this study, thereare some restrictions and

suggestions that need to be observed in futurestudies, which are as follows.

Time limitation: In industrial application, theresult should be achieved within 2 weeks, but itseems to be difficult, when faced with vague orextreme complaints, to achieve this target of finding out the root causes and improving them.

ThestudyintegratestheKanomodelandsimplestatistic methods to solve problems and increasesatisfaction. Other methods such as design of experiment (DOE), theory of inventive problemsolving(TRIZ),etc.,canbeappliedsimultaneously.

The 8Ds method is a problem-solving method.Always remember to revise some documents, suchas failure modes and effects analysis, control plan,processes, and any design records to be a forwardindicator when accomplished a problem.

Rather than trying to avoid mistakes, futurestudy that uses this method needs to encouragebreakthrough ideas regarding the true causes andto learn from the errors or experiences.

Ifaproblemoccurredandthesolutionneglectsthe attributes which must be fulfilled from thecustomer’s viewpoint or what level of goods andservices should be attained or improved to meet

customersatisfaction,the effects are merelypaperwork.

Table 8. Performance of quality and services evaluations after correction.

Evaluation item Excellent Good Fair Not good Very bad

1.Quality productsFunction (required)

a J ?

Easy to useb

J ?

Dimension stabilizationc

J ?2.Delivery (on time)

a J ?

3.Communicationb

J ?4.Documentation

a J ?

5.Packinga

J ?6.Price competitiveness

b J ?

7.Without return or get a refundd

J ?

Notes: Must-be quality.a

bAttractive quality.cOne-dimensional quality.dReverse quality.





Respecting the customer’s opinions is impor-tant.Manufacturersneednotonlyrealizewhatthecustomer’sdesiresandrequestsare,butalsoclarifytowhichcategorythoserequestsbelong.Customersatisfaction reflects the service or goods perfor-manceofacompany;ahearteningsatisfactionlevel

increases the confidence of customers in using theproduct or service and can heighten the business’scompetence.

Notes on contributors

Hsiang-Ru Chenis currently a PhD student in theDepartment of Industrial Engineering and Managementat National Yunlin University of Science and

Technology, Taiwan. He is responsible for the R&Ddepartment inJauYeouIndustry Co.,Ltd.Hisresearchinterests are in hospital management, quality manage-ment, and industrial management.

Bor-Wen Chengis a professor of Industrial EngineeringandManagementandformerDirectorofHealthServiceManagement at the National Yunlin University of ScienceandTechnologyinTaiwan.Hisresearchinterestsare in the areas of customer relationship management,service quality, and hospital management. He has a BSfrom Tunghai University in Taiwan, an MS, and PhDfrom Auburn University. He is a member of CSQC,CIIE, and CMST.

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8d in typical industries

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