This paper presented a methodology to determine a maintainability index based on assembly criteria.

Typically time is the major parameter or indicator being used measuring the maintainability, but less works are

focus on details components assembly and assembly criteria

Abdullah, Ahmad Baharuddin

Hasim, M.H

Shuib, S

Yusoff, M. S.

English

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A METHODOLOGY TO DETERMINE PRODUCT MAINTAINABILITYBASED ON ASSEMBLY CRITERIA - A CASE STUDY OF REARMOTORCYCLE BRAKE ASSEMBLYA. B. Abdullah, M. S. Yusoff, M. H. Hasim and S. ShuibSchool of Mechanical Engineering, Engineering CampusUniversiti Sains Malaysia14300 Nibong TebalPulau Pinange-mail: mebaha@eng.usm.myAbstractThis paper presented a methodology to determine a maintainability index based on assembly criteria.Typically time is the major parameter or indicator being used measuring the maintainability, but less works arefocus on details components assembly and assembly criteria. In the previous works, a customer survey and study oneffect of operator skills have been conducted. In this study, by using similar case study the maintainability index isdetermined. After the assembly type of each component is identified and represented in the form of assemblydigraph. Each of the assembly type is weighted based on their characteristics such as disassemblability, cost andassembly direction. Result from redesign shows an improvement in terms of design and maintenance efficiency.Keywords: Maintainability, assembly type, assembly digraph1 IntroductionTypically maintenance is taking care after or during product is being used hence it cost higher expense.Nowadays maintenance becomes one of the major criteria in the determining design performance. Design withmaintenance friendly features has more advantages in terms of time and cost compared to ordinary design. There arequantitative and qualitative measures used in indicating maintenance efficiency. Maintainability can be defmed asease of which the maintenance activity can be carried out on an item of product or system [7]. There are two aspectsof maintainability, serviceability and repairability. Commonly maintainability can be measured based on timeconsume in completing the task or mean time to repair (MTTR) and maintenance activity time as claimed by Utez[9]. In maintainability analysis, disassembly and reassembly is the most critical factor [3]. Balanchard et at [2] andCunningham and Cox [3] include time taken in disassembly, assembly, localization and isolation of leastreplacement of components. Ehud et at [5] measure disassembly using difficulty rating, where accessibility,position, force, additional time and special problems is interpreted based on difficulty of disassembly task. Cost ofassembly/disassembly is critical only in selection of appropriate tools [10-11]. Meanwhile Tsai et at [8] introducemodularity operations and considering reliability and maintenance cost as a measure. They also list five problemsthat should be considered in maintainability analysis, which are disassembly sequence, selection of tools, timerequired for disassembly and human factor issues such as accessibility and visibility. Clark and Parsch [4] andParsch and Ruff [6] consider a diagnosability aspect as a major factor in determining maintainability, while Waniand Gandhi [12] consider tribology aspect. Maintainability also should consider optimal resources such as personneland support equipment [7&13].The paper begins with introduction where a brief introduction and related works have been discussed.Followed by methodology of the research and then demonstrate by a case study. The result is then discussed and thepaper is end by conclusion and future works.2 MethodologyThe methodology begins with disassembly of the components in the product. During the disassemblyprocess, assembly type is identified and recorded. The methodology is summarized in the Figure 1. After thatdisassembly is constructed, where a circle with component number and an arrow to represent component anddirection of assembly. Maintainability is a function of product or system design and maintenance task design [7]. Sothat by relate it to the assembly criteria such as tools used, assembly direction, accessibility and maintenancefrequency, the maintainability index can be measured quantitatively. The relationships have been derived anddiscussed in [1].If the result of maintainability index is high or not acceptable, the designer can improve the design eitherredesign the component or by changing the assembly type. In determining maintainability index, the designer shouldchoose the most critical or the shortest path to access the targeted part.StartProduct DisassemblyAssembly TypeIdentificationAssembly DigraphConstructionNOFigure 1. Methodology used to determine maintainability index3 Case StudyIn this study, a motorcycle rear brake assembly has been used as a case study. After disassembly procedurehas been made (Figure 2), a list of components is identified as in Table 1. Note that components No. 11, 12 and 17are not in the list, while components 9, 10, 13 and 16 are not considered as component.Figure 2. Disassembly procedure of rear brake assemblyTable 1. List of components in rear brake assembly.JCom onentAxle Rear WheelRear Brake Panel Side CollarRear Brake Panel Com onentShoe Brake ComponentS rio Brake ShoeRear Brake CamDust Sheal Brake CamRear Brake Indicator#151618 Rubber Sto er Arm Wheel19 Bolt Brake Sto er20 Rear Brake Rod21 Nut Brake Road Adjustable22 Joint Brake Arms23 S rin Brake RodAfter assembly type for each of the components is identified, the disassembly digraph can be constructed.The disassembly digraph is shown in Figure 3.Figure 3. Disassembly digraph of the rear brake assemblyThe maintainability index can be more systematically determined by using stand chart. For that purpose aMaintainability Evaluation Chart (MEC) has been developed, where maintainability for each of the individualcomponent can also be identified, named maintainability degree. In the chart maintenance rate is used to represent ofhow frequent the component need to be maintained. After the calculation has been made, the result is as shown inTable 2.Table 2. The maintainability index for rear brake assemblyRear Brake Drum Assemblv# Maintenance Critical Assembly MaintenanceCompo Name Rate,Mr Path, Cp Score, Ar Deeree,Md1 Axle Rear Wheel 1 1 14 0.072 Rear Brake Panel Side Collar 1 2 18 0.063 Rear Brake Panel Component 1 3 22 0.054 Shoe Brake Component 4 4 26 0.155 Spring Brake Shoe 3 5 30 0.106 Rear Brake Cam 1 6 34 0.037 Dust Sheal Brake Cam 2 5 30 0.078 Rear Brake Indicator 1 3 22 0.0515 Rear Brake Arms 1 2 18 0.0618 Rubber Stopper Arm Wheel 2 3 18 0.1119 Bolt Brake Stopper 2 5 36 0.0620 Rear Brake Rod 1 4 26 0.0421 Nut Brake Road Adjustable 2 1 14 0.1422 Joint Brake Arms 1 2 18 0.0623 Spring Brake Rod 2 3 22 0.09Maintainability Index= 1.124 Conclusion and Future worksThe paper has presented the methodology to detennine maintainability index by using rear brake assemblyas a case study. The contribution of this work is that, the developed methodology can be used to measurecomponent, product and system maintainability. The approach used is very simple and can be used easily byutilizing the standard chart named Maintainability Evaluation Chart (MEC). This approach is more practical and theresult is consistence. For the future works, a Maintainability Index Template is to develop in order to automate thecalculation process and can be used as online.AcknowledgementThe authors would like to thank the School of Mechanical Engineering and Universiti Sains Malaysia for theircooperation and fund provided (AIC 6035101).References1. Abdullah, A. B. and Ripin,Z. M., (2005). Kaedah Pengukuran Indek Keboleh-selenggaraan Produk Atau SistemBerdasarkan Kriteria Pemasangan, Jurnal Teknologi (A), 42: 91-106.2. Balanchard, B. S Verma, D. and Peterson, E. L., (1995). Maintainability, New York: John Wiley and Sons.3. Cunningham, C.E. and Cox,W., (1972). Applied Maintainability Engineering, New York: Wiley and Sons.4. Clark, G.E. and Paasch, RK., (1996). Diagnostic Modeling and Diagnosability Evaluation of MechanicalSystems, J. Mech. Design, 118(1): 425-431.5. Ehud, K., Brent, B. and Antony, P., (1996). Methodology to Evaluate Ease of Disassembly for ProductRecycling, IIE Transactions, 28(28): 837-845.6. Paasch, R K. and Ruff, D.N., (1997). Evaluation of Failure Diagnosis in Conceptual Design of MechanicalSystem, J. Mech. Design, 119(1): 57-67.7. Rosenberg, 1., (2000). Can We Measure Maintainability. Citing internet sources URLhttp://members.aol.com/geshome/wess2000/jrwess.PDF8. Tsai, Y.T., Wang, K. S. and Lo, S.P., (2003). A Study of Modularity Operation of Systems Based onMaintenance Consideration. J. Eng. Design, 14(1): 41-56.9. Utez, R., (1983). Maintainability of Production System, Maintenance Management International, 455-468.10. Vujosevic, R. , (1995). Maintainability Analysis in Concurrent Engineering of Mechanical System, CERA, 3(1):61-7311. Vujesovic, R., Raskar, R., Yeturkuri, N.V., Jothishankar, M. C. and Juang.. S-R., (1995). Simulation,Animation and Analysis of Design Disassembly for Maintainability Analysis, Int. J. Production Research,33(1): 2999-3022.12. Wani, M.F. and Gandhi, O.P., (2002). Maintainability Design and Evaluation of Mechanical Systems Based onTribology, Reliability Eng. and System Safety, 77: 181-188.13. Wani, M. F. and Gandhi, O.P., (1999). Development of Maintainability Index for Mechanical Systems,Reliability Eng. and System Safety, 65: 259-270.J

A Methodology To Determine Product Maintainability Based On Assembly Criteria - A Case Study Of Rear Matorcycle Brake Assembly.

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A Methodology To Determine Product Maintainability Based On Assembly Criteria - A Case Study Of Rear Matorcycle Brake Assembly.

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