PREDICTION OF REPAIR & MAINTENANCE COSTS OF DIESEL ENGINE D.R.Dolas 1, M.D. Jaybhaye 2, Sudhir. D. Deshmukh 3 1, 3 Department of Mechanical Engineering, MGM s Jawaharlal Nehru Engineering College, Aurangabad, Maharashtra 431003, India. 2 Department of Production Engineering, College of Engineering Pune, Pune, Maharashtra - 411005, India. ABSTRACT Diesel engine is widely use for different applications, the failure frequency of diesel engine is more increase to increase the age & use of engine in order to take decision to replacement of engine on the basis of Repair & Maintenance cost (R&M) & predication of future Repair & Maintenance costs of diesel engine used in Borewell compressor. Present case study discusses prediction of accumulated R&M costs (Y) of Diesel engine against usage in hours (X). Recorded data from the company service station is used to determine regression models for predicting total R&M costs based on total usage hours. The statistical results of the study indicates that in order to predict total R&M costs is more useful for replacement decisions than annual charge. KEYWORDS Diesel Engine, R & M Cost, Maintenance, Regression Model, Age replacement model. 1. INTRODUCTION Diesel engine is one of the most important power sources in different applications. Effect of diesel engine power on Borewell compressor is considerable. The use of Borewell compressor for making tube wells during latter decades resulted in rapid growth of farm & requirement drinking water. Costs of owning and operating including the preventive & corrective maintenance cost of diesel engine is very important for deciding the appropriate time to replace the diesel engine on basis of repair & maintenance cost. The new engine failure are occurring rarely therefore less maintenance cost, but age increase the maintenance cost is increase. G.M. Khoub et al. [1] presented the repair & maintenance cost model on the basis of mean working hours & mean accumulated cost of MF285 tractor. To predicate repair & maintenance cost the power model most suitable. Development of model for predication Repair & maintenance cost for two wheel drive tractor & suggested strongly the polynomial model by Ranjba et al. [2]. Khodabakhshian R. & Shakeri M carried out the statistical analysis of different farm tractors on the basis of repair & maintenance cost & total working hour using Preventive Maintenance [3]. Donca Gh. [4] mean accumulated maintenance cost of U683dt tractor analysis using different model & recommended power model best model for predication the maintenance cost. The study was conducted by Shahram et.al. [5] For JD-4955 tractors showed that the polynomial regression model strongly recommended in order to predict accumulated R&M costs. R. Ahmad [6] proposed a maintenance management decision model for preventive maintenance application & determines the revised PM interval for machine. Fereydoun proposed model provides for the 63
Prediction of repair and maintenance costs of Massey Ferguson 285 (MF-650) tractors & suggested polynomial regression model [7]. Artificial neural network technique is used for predication of repair & maintenance cost & recommended this is best tool. [8]. Isaac & et al. [9] presented the cubic polynomial least square regression cost prediction. Sebo et al. [10] determine optimum replacement model for replacement machine using least squares method. Y. H. Chien & J. A. Chen [11] uses of age replacement model determine the average cost per unit time. K. Yao & D. A. Ralescu [12] provide the age replacement policy involving random age has been proposed & assumed the age of the unit is an uncertain. Shey Huei Sheu1 & Chin-Chih Chang [13] using the age replacement models determine optimal age for preventive replacement cost can be minimized. The aim of this study is to provide a statistical analysis for the repair and maintenance costs of diesel engine of application for Borewell compressor in order to present an appropriate mathematical model implementation of appropriate models for the repair and maintenance costs of diesel engine provide planner and policy makers and also owner an opportunity to evaluate performance of diesel engine economic. 2. DATA COLLECTION This study is carried out at authorized service station. Failure & maintenance cost data is collected & sorted from forty same make & model diesel engine. Corrective & preventive maintenance cost estimated using age replacement model. 3. DETERMINATION OF COST PER HOUR USING AGE REPLACEMENT MODEL To determine the repair & maintenance cost per hour using Age replacement model Cf Ft+ Cp Rt CT= 1 Age replacement model is more useful in practical application for the determine of Repair & maintenance cost (preventive & corrective ) & estimate maintenance cost per hour. To determine the cost function C (T). Using Weibull distribution model [6] is shown in equation. (2) Cf 1 + Cp CT= 2 Where: C f - Failure cost C p - Preventive replacement cost C s cost of spare parts F (t) = Cumulative distribution function R (t) = Reliability function FT=1 RT= e η β FT+RT=1 η Scale parameters (characteristic life), β- Shape parameters (variation of the failure rate) Failure cost & preventive replacement costs can be determine using following equations C =C +C & Cp=C +C Where: C f - Failure cost C p - Preventive replacement cost C r - Cost of replacement system & components C d - Cost of down time C i - Cost preventive servicing Cost of down time = one hour cost = 90 (ft) 60 (Rs) = 5400 Failure / hour 64
Estimation of reliability of diesel engine using Weibull distribution using failure data & maintenance cost per hour. The system probability of failure function = FT=1 3 The system reliability function = RT= e η β 4 FT+RT=1 5 t = 3000 hours, β = 2.198 & η = 1929.46 F(t) =1 -.. = 1 -.. = 1 -. = 1-0.14= 0.86 R(t) = 1-F(t) = 1-0.86 = 0.14 Table 1. Estimation of average cost per hour 65
4. PREDICATION MODEL DEVELOPMENT: To estimate the appropriate repair & maintenance cost model for diesel engine using different regression models, as per different researchers presented & suggested the regression model for farm tractors are [2], [3], [4]. Y=a+bx Y=a+bx+cx Y=a+lnbx Y=ae Y=ax Linear Polynomial Logarithmic Exponential Power Fig. 1 Regression models of maintenance cost of diesel engine 66
Development of appropriate mathematical model for predicting repair and maintenance costs for diesel engine, using repair & maintenance cost of forty diesel engines Table 1. The presented data in this Table 1 is used to analysis and determine the predicated repair and maintenance cost per hour as shown in Table 2. Table.2 Repair & Maintenance Cost per Hour Cost/ Hours 400 300 200 100 0-100 C(T) y = 0.004x + 71.78 R² = 0.635 y = 61.81e 4E-05x R² = 0.472 y = 32.15ln(x) - 145.4 R² = 0.678 y = -1E-07x 2 + 0.008x + 61.88 R² = 0.676 y = 5.551x 0.348 R² = 0.693 0 10000 20000 30000 40000 50000 Time Linear Expon. Log. Poly. Power Fig. 2 Maintenance cost Predication Regressions model of diesel engine 67
Table.3 Regression models Regression Models R 2 Linear Y=a+bx 0.635 Polynomial Y=a+bx+cx 0.676 Exponential Y=ae 0.472 Logarithmic Y=a+lnbx 0.678 Power Y=ax 0.693 5. RESULT & DISCUSSION Table 3 presents regression models for predication the repair and maintenance cost per hour of diesel engines. The Power model correlation coefficient is highest value(0.693) compared to other models. Therefore recommended that the Power model best model for Borewell compressor diesel engine In the most of researchers published studies in this field of Farm equipment, machinery & tractors suggested the Power model gave better cost prediction with higher confidence and less variation than that of Exponential and logarithmic models. Because of, easiness in calculations, the small difference between the correlation coefficients of Polynomial and Power models and using of Power model by other researchers, As per Table3 other models are less significant. 6. CONCLUSION The Repair & Maintenance costs prediction of Borewell compressor diesel engine & deciding the time to replacement. The repair coefficients values are generally dependent on factors such as research method performance and time spans, number and type of samples. Results of this study indicated that the Repair & Maintenance costs per hour increased with engine age. This resulted in a marginally increased total repair cost curve. These results also confirmed that there are considerable variations in Repair & Maintenance costs among engine models as well as individual ones. For circumstances similar to this study, estimates suggest that annual R&M costs increase with age of engine. This method is more useful for replacement decisions than annual charge. ACKNOWLEDGEMENT The authors are deeply grateful for help and guidance rendered by General Manager Mr. Yuvraj Lavhale and employees of Trinity Mahalasa Durga sales & services, Aurangabad during field studies. 68
REFERENCES [1] G.M. Khoub bakht, H. Ahmadi, A. Akram and M. Karimi,( 2008) Repair and Maintenance Cost Models for MF285 Tractor: A Case Study in Central Region of Iran, American-Eurasian J. Agric. & Environ. Sci., 4 (1): pp 76-80, [2] Iraj Ranjba, Majid rashidi, Borzoo Gharee I Khabba,( 2010), Prediction of repair and maintenance costs of two-wheel Drive tractors in iran, XVII th World Congress of the International Commission of Agricultural and Biosystems Engineering (CIGR) pp 1-10 [3] Khodabakhshian R.& Shakeri M.,( 2011), Prediction of repair and maintenance costs of farm tractors by using of preventive maintenance, International Journal of Agriculture Sciences, Vol. 3, Issue 1, pp-39-44 [4] Donca Gh.,( 2011 ) Maintenance cost model for U683DT Tractor, Analele Universita Nii din Oradea, Fascicula: Ecotoxicologie, Zootehnie i Tehnologii de Industrie Alimentara, pp 131-136 [5] Shahram Mohseni Niari, Raj Ranjbar and Majid Rashidi, (2012), Prediction of Repair and Maintenance Costs of John Deere 4955 Tractors in Ardabil Province, Iran, World Applied Sciences Journal 19 (10): 1412-1416 [6] R. Ahmad, S. Kamaruddin, I. Azid, I. Almanar,( 2011), Maintenance management decision model for preventive maintenance strategy on production equipment, J. Ind. Eng. Int., 7(13), pp 22-34 [7] Fereydoun Keshavarzpour, (2011), Prediction of Repair and Maintenance Costs of Massey Ferguson 285 Tractors, Agricultural Engineering Research Journal 1 (3), pp 63-67, [8] Abbas Rohani, Mohammad Hossein Abbaspour-Fard, Shamsolla Abdolahpour, (2011), Prediction of tractor repair and maintenance costs using Artificial Neural Network, Expert Systems with Applications(Elsevier Ltd ) vol 38 pp 8999 9007 [9] Isaac, O. Ajao,Adedeji, A. Abdullahi &Ismail, I. Raji,(2012) Polynomial Regression Model of Making Cost Prediction In Mixed Cost Analysis, Mathematical Theory and Modeling Vol.2, No.2, pp 14-23 [10] J. Sebo, J. Busa, P. Demec, J. Svetlík, (2013), Optimal replacement time estimation for Machines and equipment based on cost function, METALURGIJA 52, 1, pp 119-122 [11] Y. H. Chien & J. A. Chen, (2007), Optimal Age-Replacement Model with Minimal Repair Based on Cumulative Repair Cost Limit and Random Lead Time, Proceedings IEEE IEEM, pp 637-639 [12] K. Yao & D. A. Ralescu, (2013), Age replacement policy in uncertain Environment, Iranian Journal of Fuzzy Systems Vol. 10, No. 2, pp. 29-39 [13] Shey Huei Sheu1 & Chin-Chih Chang,(2008), Optimal age-replacement model with minimal repair based on a cumulative damage limit policy, International Journal of Pure and Applied Mathematics, Volume 48 No. 4, pp 569-584 Authors Shri. Dolas Dhananjay R, BE (Mech) & ME- Mechanical (Design Engineering) working as a Associate Professor in Mechanical engineering at MGM S Jawaharlal Nehru College of Engineering, Aurangabad. He has 6 publications in National/International conferences & Journals & Pursuing PhD Dr.Maheshwar D Jaybhaye, Ph.D (Mech.Prod.Engg.) Working as AssociateProfessoer, Production Engineering Department at College of Engineering, Pune. He has 16 publications in National/International conferences & Journals. He is life member of ISTE, Tribology Society India, Operation Research Society of India & Associate Member of Associate Member Institution of Engineers (India). He is recipient of K.F.Antia memorial Award (Gold Medal) from Institution of Engineers (India). Dr. Sudhir D Deshmukh, Ph.D (Mechanical Engg.) working as Principal MGM s Jawaharlal Nehru College of Engineering, College, Aurangabad. He has more than 25 publications in his credit in National/International conferences &Journals. He is life member of ISTE and Fellow Member of Institution of Engineers (India), Fellow of Institution of Production Engineers, Chartered Engineer & Chairman, Quality Circle Forum of India (QCFI), Aurangabad. 69