This paper discussed the relationship between design for modularity and maintenance in order to extend product life

Abdullah, Ahmad Baharuddin

Hasim, M.H

Mohd Ripin, Zaidi

Shuib, S

English

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Proceedings of the International conference on Recent Advances in Mechanicat & M"t r,"bt$lly"Eil;30-31 May 2005, Kuala Lumpur, MalaysiaPaper No. 3EFFECT OF DESIGN FOR MODULARITY ON PRODUCT MAINTAINABILITY - APRELIMINARY STUDYA. B. Abdullah*, M. H. Hasim, Z. M. Ripin and S. Shu,bSchool Of Mechanical Engineering, Universiti Sains Malaysia Engineering Campus14300 Nibong Tebal, Pulau Pinang, Malaysiae-mail: mebaha@eng.usm.my*ABSTRACTThis paper discussed the relationship betweendesign for modularity and maintenance in order toextend product life. Modularization can beI l described as an engineering approach to simplify\ -, component or product configuration as functionalindependence it creates. This loose interactioncharacteristic makes the maintenance processeasier. In this preliminary study, experiment isconducted to measure the maintainability in term ofmaintenance time. A case study of drum brake iscarried out to clarify this work. At this stage, asurvey and time study have been conducted andthe result is presented.Keywords: Maintainability, modularity, assemblydigraph, timeINTRODUCTIONProper maintenances can extend product life-cycle.ln maintenance time to repair (TTR) is very crucialand it depends mainly on the producUsystemconflgurations. By simplifying the product. .. configuration, repair and maintenance can bef-! accomplish in shorter time Modularity is believed'- - capable to makes maintenance simpler due tofunctional independence created in the productconfiguration [1].This study is split into three phases. Phase1 involve determination of maintainability indexbased existing quantitative measure such as time,accessibility and assemblability. Phase 2 consist ofconstruction of new index of maintainability bytaking into consideration every aspect andparameter that could affect the maintenanceincluding frequency of maintenance and repair. lnPhase 3, the modularity effect to the maintainabilityindex is measured by conducting several casestudies. This paper is part of phase 1.The paper is organized as the followingsteps. lt begins with introduction and then the resultof the customer survey result is tabulated.Furthermore the methodology used is presented. Atime study is also conducted. Result is thendiscussed and the paper ends with conclusion.RELATED WORKSThere are several quantitative measure used indetermining maintenance efficiency. Maintainabilitycan be measured based on time consume incompleting the task or mean time to repair (MTTR)and maintenance activity time as claimed by Utez[2]. ln maintainability analysis, disassembly andreassembly is the most critical factor l3l.Balanchard et al. [4] and Cunningham and Cox [5]include time taken in disassembly, assembly,localization and isolation of least replacement ofcomponents. Ehud et al. [6] measure disassemblyusing difficulty rating, where accessibility, position,force, additional time and special problems isinterpreted based on difficulty of disassembly task.Cost of assembly/disassembly is critical only inselection of appropriate tools [7]. Meanwhile Tsai etal. t8l introduce modularity operations andconsidering reliability and maintenance cost as ameasure. They also list five problems that shouldbe considered in maintainability analysis, which aredisassembly sequence, selection of tools, timerequired for disassembly and human factor issuessuch as accessibility and visibility. Clark and Parsch[9] and Parsch and Ruff [10] taken diagnosabilityaspect as main consideration in determiningmaintainability, while Wani and Gandhi [11]consider tribology aspect. Maintainability alsoshould consider optimal resources such aspersonnel and support equipment [12].CUSTOMER SURVEYA survey has been conducted to identify the mostfrequent part that requires routine maintenance orrepair. There are two types of customer have beenshortlisted, i.e. the customer who directly used theelproduct and the mechanic who dealing with repair,replace or maintain the product. Note that tires andtube are not taken into consideration. As a resultmost of the customer claimed that the mostfrequent (every 4-6 months) is the brake shoewhich is about 71.5% as shown in Table 1. Thiscomponent is used to stop drum brake rotation byproviding restraint to the inner brake drum surface.From mechanic point of view, 72o/o of the brakeshoe needs to be change and only 14o/o eachrequires cleaning or adding oil as shown in Figure1, As shown in Figure 2 most of the user claimedthat assembly method and component locationplays an important role in disassembly process.Table 1Fig. 1 The most frequent maintenance works for drumbrake.Effect of Assembly Method andGomponent Location to MaintainabllityE60fso8. aoE*3zooEro2oI Assembly MethodI ComponentLocationFig. 2 Customer responds on effect of assembly methodand component location to maintenance.From the survey, the customer recommended thatfor future design of the drum brake, theconfiguration need to be simplified and should behandled by a skillful and experience mechanic.Gustomer RecommendationsOperatorskill43loFig. 3 Customer reoommendationMETHODOLOGYFor this work, the maintainability is studied basedon maintenance time. Experiment will be conductedby involving operator with different background frombeginner with no experience to expert whomdealing with the job daily. The overall methodologyused in this project is as shown in Figure 4.Maintenance WorksCleaning Add Oil14% 14Yo-Changing72YoFig. 4 The overall methodology of the study\V(i -tarai.l * i P-''r' Wf-" *,A,bMotorcycle braking system consists of severalcomponents such as drum brake, brake lining,paddle and brake shoe. As a result form survey,brake shoe is the most frequent. In order to accessthis part, the operator requires disassemblingseveral other parts such as motor cycle wheel,shaft, brake cam lever and etc. Figure 5 show thebrake system of the motorcycle and its componentlabel. This will prolong in time to repair (TTR) ormaintain $fM) of the desired parts. Moreover themulti-type of assembly methods used alsocontributing to the complexity of the process. Forthat reason, an experiment regarding to the motorcycle brake system maintenance need to bestudied.ieal 11 1lear Backino Plate Bolt 12 1/Vasher 2 13 1lhain Adiuster Nut 14 1lear Bactino Plate Nut 15 1iide Stand Bolt 16 1/Vasher 3 17 1ffasher 4 18 1lplit Pin 19 1ilrake Lever Nut 20 1)addle 2'l 1Stand 22 1Sorino. Stoo Switch 23 1iorinq. Paddle 24 1jprino, Stand 25'took zor,lut 27 1)in 28 1Sorino 29 1tod 30 1tin M2x16 31 1tin M2x16 32 1yVasher. M17Y22 33 1Alasher. 5mm 34 1lubber Cushion 35 1Fig. 5 An exploded view and component listing ofmotorcycle drum brake assemblyEXPERIMENTAL SETUPThe objective of the experiment is to investigate thedisassembly time for the brake shoe for repairing orreplacement. Figure 6 demonstrate the rear brakingsystem to represent the rear braking system of themotorcycle.Fig. 6 Rear brake assembly for experimentationEach steps involve in disassembly processrecorded. Figure 7 show the disassembly steps.fItt'rhtart Name # Part Quantity)hain Adiuster 1 1Lear Axle Bolt 2lear Wheel Spacer 3 1lear Backino Plate 4 1lrake Shoe c 2]rake Shafl 6 1lear Brake Indicator 7 1Srake Shoe Sprino I 2Srake Cam Lever Rear I 1A/asher 1 10 1()Fig. 7 Brake shoes disassembly processAfter that, the disassembly digraph is constructed todemonstrate the disassembly process. Figure 8depicts the disassembly digraph. The disassemblyprocess start by unscrewing the nut from the shaft(Part no. 2)Fig. I Disassembly digraph of the rear brake systemassemblyThe numbers represent the components as listed inFigure 5 and the arrows demonstrate the sequenceof disassembly process till the targeted parts isachieved. Time is taken after the brake shoes aredisassembled.SIMULATION RESULTAs a result from the simulation, the average time isabout 2 to 5 minutes for disassembling the parts tillaccessing the brake shoe as simplified in Table 2.2. ResultOperator Level Average Time, t"uoBeqinner 5 min 6 sec.Intermediate 2min22sec.Expert 1 min 15 sec.CONCLUSION AND FUTURE WORKSThe study indicated that maintainability can bemeasured on time basis and it depends on thecomponent accessibility, location of the targetedcomponents and the skill of the operator. The lesserworkload requires in accessing the component, thebetter maintainability. Moreover the higher level ofskill of the operator, the faster maintenance can bedone.For the future work, other aspect such asfrequency of component to be maintained andeffect of assembly type for maintainability will bestudied.AcknowledgementThe authors would like to thank the School ofMechanical Engineering and Universiti SainsMalaysia for their cooperation and fund provided(A/C 6035101).REFERENCESJ.K. Gershenson and G.J. Prasad, ProductModularity and its effect on Service andMaintenance, Proc. of the 1997 Maintenanceand Reliability Conference, Knoxville, May1997, Tennessee.H. Utez, Maintainability of Production System,Maintenance Management lnternational, pp.455-68, (1983).C.E. Cunningham and W. Cox, AppliedMaintainability Engineering, Wiley and Sons,New York, (1972).R.Vujesovic, R.Raskar, N.V. Yeturkuri, M.C.Jothishankar and S-H. Juang.. Simulation,Animation and Analysis of Design Disassemblyfor Maintainability Analysis, lnt. J. ProductionResearch, vol. 33, no. 1, pp. 2999-3022,(1ees).B.S.Balanchard, D. Verma and E.L Peterson,Maintainability, John Wiley and Sons, NewYork, (1995).1.4.5.++6.7.8.LK.Ehud, B. Brent and P.Antony, Methodology toEvaluate Ease of Disassembly for ProductRecycling, llE Transacfions, vol. 28, no. 28, pp,837-845, (1996).R. Vujosevic, Maintainability Analysis inConcurrent Engineering of Mechanical System,CERA, vol.3, no. 1, pp.61-73, (1995).Y.T. Tsai, K.S. Wang and S.P. Lo.. A Study ofModularity Operation of Systems Based onMaintenance Consideration. J. Eng. Design,vol. 14, no. 1, pp.41-56, (2003).G.E. Clark and R.K. Paasch, DiagnosticModeling and Diagnosability Evaluation ofMechanical Systems, J. Mech. Design, vol. 118,no. 1, pp. 425-431, (1996).10. R.K. Paasch and D.N. Ruff, Evaluation ofFailure Diagnosis in Conceptual Design ofMechanical System, J. Mech. Design, vol. 119,no. 1, pp. 57-67, (1997).1 1. M.F. Wani and O.P. Gandhi, MaintainabilityDesign and Evaluation of Mechanical SystemsBased on Tribology, Reliability Eng. andSystem Safety, vol. 77, pp. 1 81 -1 88, (2002).12. M.F. Wani and O.P. Gandhi, Development ofMaintainability Index for Mechanical Systems,Reliability Eng. and Sysfem Safety, vol. 65, pp.25e-270, (1gee).

Effect Of Design For Modularity Maintainability-A Premilary Study.

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Effect Of Design For Modularity Maintainability-A Premilary Study.

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