STUDY ON THE DEFECTS AND TO IMPROVE THE PROCESS CAPABILITY OF TREAD RUBBER USING DMAIC METHODOLOGY

International Research Journal of Engineering and Technology (IRJET) e ISSN: 2395 0056

Volume: 09 Issue: 07 | July 2022 www.irjet.net p ISSN: 2395 0072

STUDY ON THE DEFECTS AND TO IMPROVE THE PROCESS CAPABILITY OF TREAD RUBBER USING DMAIC METHODOLOGY

1PG Student, Department of Production Engineering, GEC Thrissur, Kerala, India 2Assistant Professor, Department of Production Engineering, GEC Thrissur, Kerala, India ***

Abstract - The customer satisfaction is one of the keys that lead to the success of every business organization. It is the extent of the products that meets the customer demands. This differentiates the organization from the competitors in the market and gives the competitive advantage. This paper aims to evaluate processes in a tread rubber manufacturing company and to find out the process capability using DMAIC (Define, Measure, Analyze, Improve and Control) methodology. This paper also investigates about various kinds of defects in the tread rubber manufacturing. The DMAIC methodology improves the process and enhances the quality of the product. The problems in tread rubber manufacturing are variation in the tread rubber dimension and some defects which appear in the extrusion process. Using this DMAIC methodology the process capability can be improved and other defects can be rectified by various modifications.

Key Words: Six Sigma, DMAIC, Defect Analysis, Process Capability, Tread rubber manufacturing.

1. INTRODUCTION

Todaythetechnologyisevolvingdaybyday.Manyproducts are invented and evolved by using these technologies in order to fulfil the need of the people. The needs of the customers are always changed over the time. An organizationwillonlysucceedbysatisfyingtheneedofthe customer.Inthecurrentpandemicscenario,everybusiness is build over the trust and relationship between the customer and manufacturer. The evolution of the tyres makesthelifeofthemaneasyandfaster.Theincreaseinthe number of vehicles increases the demand of the tyres rapidly.Thequality,performanceanddurabilityofthetyres areveryimportantinthesatisfactionofthecustomers.The qualitytyresmustconformtoitsspecificationsandfreefrom anykindofdefects.Therearemanymethodologiesandtools used by the companies for the continuous improvement. Among them, DMAIC methodology is a well known improvement cycle used by the companies. The DMAIC methodologyisanimprovementcyclewhichcanbeusedin every process. It is the acronym for Define, Measure, Analyze,ImproveandControl.

1.1 Tread rubber

Thetreadrubbercompoundistheintermediateformofthe actualtyre.Itistheportionthatprovidestheadequategrip andfrictionontheroad.Asithasmorecontactontheroads, thereisahighchanceforwearandtear.Sothequalityofthe treadisverysignificantindeterminingtheperformanceof eachtyre.Thetreadrubberismanufacturedbya seriesof processessuchasmixing,calendaring,extrusionetc.Theraw materials used for the tread rubber are natural rubber, syntheticrubber,carbon,chemicalsetc.Therawmaterials aremixedinanintermixerandthenitundergoaseriesof calendaring.Finallyitisextrudedthroughaparticulardie.

1.2 DMAIC methodology

DMAICisanimportantqualitymanagementtoolthatcanbe used as a method of quality improvement among many others. DMAIC is an abbreviation for Define Measure Analyze Improve Control. This method is based on the Deming cycle of process improvement. It is the process of improvingmanydifferentareasoftheenterprise.TheDMAIC cycleismadeupoffiveinterconnectedstages[3].

Fig 1: DMAICmethodology

International Research Journal of Engineering and Technology (IRJET) e ISSN: 2395 0056

Volume: 09 Issue: 07 | July 2022 www.irjet.net p ISSN: 2395 0072

1.2 Scope of the project

The improvement in every aspects of the production processincreasesthequalityofproductsandtherebyvalue of the company. The DMAIC methodology helps to understand the problems related to the process, its constraints etc. It will solve every issue regarding the process,wastage,andqualityinordertomaketheprocess more efficient and reliable. This methodology has a systematicway to rectifyanykindofproblems. There are many tools that are used under DMAIC for improving the process.InthisprojectDMAICmethodologywillimprovethe currentprocessbyrectifyingeachdefect.

2. RESEARCH METHODOLOGY

2.1 Define

ThisinitialstageoftheDMAICmethodologyiscriticaltothe project's success, and a thorough characterization of its componentsisrequired.Tothatpurpose,aprojectplanwas created, which defined the challenge and the goals to be achieved,aswellasthescopeandteamsparticipating.

defectssuchasbubbles,cracks,softregioninthecentreof theextrudateandsharpedgesonthetreadrubber.

2.2 Measure

In this phase, information gathered in order to assess processcapabilities.Analyzingtheprocessontheextrusion lines was part of a data collection inorder to identify the defects. The dimensions of 30 samples of T DURA tread rubber were measured and process capability index and process capability ratio are determined in order to check whether the process is capable or not. For width, process capability index (Cpk) is 0.64 and process capability ratio (Cp) is 0.65. For thickness, Cpk and Cp are 0.59 and 0.62 respectively Fromthisphase,itisclearthatprocessisnot capable.

2.3 Analyze

The goal of this phase was to identify the fundamental causes of defects and reasonsof variation in the process. Duringtheanalyzephase,theprocesswasstudiedtoidentify potentialapproachestobridgethegapsbetweenthecurrent quality performance of the process and the target established.Thex barandR chartarequalitycontrolcharts thatareusedtoevaluatethemeanandvariationofaprocess based on samples collected over a specific time period. In both charts,control limits are used to track the mean and variationoftheprocessasitprogresses.Fromthecontrol chartofwidthandthickness,thedeviationfromtargetvalue areidentified.Forexample, analysisofthicknessisshown below.

Fig 2: Treadrubbermanufacturingprocesses

In the first phase, the processes of tread rubber manufacturingareevaluatedandstudied.Thetreadrubber is manufactured by a series of processes such as mixing, calendaring,extrusion etc.Theraw materialsusedfor the treadrubberarenaturalrubber,syntheticrubber,carbon, chemicalsetc.Theproblemsareidentifiedandtheproject goals and objectives are defined to improve the current process. The problems identified in the tread rubber manufacturing are fluctuation in the extrudate geometry,

Chart 1: Deviationofthickness

International Research Journal of Engineering and Technology (IRJET) e ISSN: 2395 0056

Volume: 09 Issue: 07 | July 2022 www.irjet.net p ISSN: 2395 0072

Chart 2: x barandR chartofthickness

Fromthex barandR chart,itisclearthatthevariationsof thicknessareundercontrol.Buttheprocessisnotcapableto conform the product to the required specification limit. A processisconsideredtobecompetentifalmost100percent of its output meets the standards. Here process is in command while still failing to meet specification requirements.Thisresultissameasforwidth.

Followingdataanalysis,anIshikawadiagramwascreatedto establishcause and effectrelationships.

The common failure or flaws in the rubber is same as of everyextrusionprocess.Thethreemaincausesaremould design, material selection, and processing. Failures occur duringprocessinginmanycircumstances,andthesefailures produce defects in extruded components such as rough surface,extrudersurging,thicknessvariation,unevenwall thickness, diameter variation, and centering difficulty. Processing flaws in extrusion goods include a lack of understanding of the processing procedure, the use of insufficientorobsoletemachines,alackofskilledpersonnel, machine breakdown, and inappropriate working surroundings.

2.4 Improve

During the improvement phase, various approaches to accomplish things better and faster at a lower cost were examined.Theremediesforthedefectsareidentified.The percentageoflosswouldbereducediftheabovesolutions wereused.

Table 2: Remediesforthedefects

S.No Defect Remedies

Ishikawadiagram

Theimplementationisnotsoeasy.Personnelareresistantto change.Theyarecontentwiththewaythingsare.Itrequires moresupport from the management. Theimplementation mayrequirecapitalinvestment.Themeasurementprocessis repeatedafterimplementation.Thenewprocesscapability indexandprocesscapabilityratioaredetermined Forwidth, processcapabilityindex(Cpk)is0.69andprocesscapability ratio(Cp)is0.7.Forthickness,CpkandCpare0.75and0.65 respectively.Analysisafterimplementationisshownbelow.

International Research Journal of Engineering and Technology (IRJET) e ISSN: 2395 0056

Volume: 09 Issue: 07 | July 2022 www.irjet.net p ISSN: 2395 0072

3. RESULT

AftertheimplementationwecanseetheProcesscapability indexCpkandProcesscapabilityratioCpareincreased.The variations of both width and thickness are under control. Theprocessismuchcapabletoconformtheproducttothe requiredspecificationlimit.Theprocessisconsideredtobe competent if almost 100 percent of its output meets the standards. Here process is not 100 percent perfect but it meetsspecificationrequirementsprecisely.

Table 3: Beforeimplementation PROCESS CAPABILITY INDICES BEFORE AFTER

Chart 3: Deviationofthickness

Chart 4:

x barandR chartofthickness

From the control chart of thickness, we can see the deviations from target value are reduced. Here the dimensions are more conform to the target value. The process capability is increased. This result is same as for width.

2.5 Control

Thecontrolstageverifiesthequalityofthemodifiedprocess to determine whether the changes introduced during the enhancestagearesufficientandongoing.Italsomanagesthe process'sfuturestateinordertolimitdeparturefromthe objectivesandassurethatthecorrectionismadebeforeit has a negative impact on the process's outcome. The progressmadeinpreviousstepsmustbemaintainedfora long time in order for the organization to continue to succeed. We use the control phase to keep these process improvementsgoing

Processcapabilityindex Cpk 0.64 0.69 Processcapabilityratio Cp 0.65 0.7

Table 4: Afterimplementation PROCESS CAPABILITY INDICES BEFORE AFTER

Processcapabilityindex Cpk 0.64 0.69 Processcapabilityratio Cp 0.65 0.7

4. CONCLUSION

Inthefirstphase,problemisidentifiedandtheprojectgoals andobjectivesaredefinedtoimprovethecurrentprocess.In the second phase, process capability index and process capabilityratioaredetermined inordertocheck whether the process is capable or not. From the findings it is clear thattheprocessneedsimprovement.Inthethirdphasethe remediesforthedefectsidentified.Somemodificationsare doneandnewprocesscapabilityisdeterminedinthefourth phase.Actuallytechnologyupgradationisrequired.Inthe fifth phase control is to be achieved for continuous improvement.

4.1 Suggestions

1. Modernization

Thetechnologyupgradationisneeded.Anextruderhaving automatictemperatureandpressurecontrolisrequired.

2.

Propertraining

Proper training is needed in each operations for the employersisnecessary

3.

Predictivemaintenance

Themaintenanceistobedoneinaplannedmanner

International Research Journal of Engineering and Technology (IRJET) e ISSN: 2395 0056 Volume: 09 Issue: 07 | July 2022 www.irjet.net p ISSN: 2395 0072

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