Reliability Modeling of Draglines for Availability Estimation and Maintenance Planning

Demirel, Nuray
Düzgün, Hafize Şebnem
Walking draglines are the dominant production equipment for overburden excavation in surface strip mining operations. Given that the average unit cost of production by dragline is US$ 3.5/m3 for coal, the one percent increase in the machine productivity can provide significant benefits to the industry. Effective use of draglines requires a thorough knowledge of machine productivity, efficiency, and reliability. Production engineers must be guided by appropriate strategies to preserve the structural and operating performance of draglines. Modelling dragline reliability is a valuable tool to estimate the dragline’s long-term preventive and corrective maintenance times and availabilities, to develop preventive maintenance plans, and to make future projections about the machine’s performance. This paper presents the development of reliability models for two walking dragline units of Marion 7820 (40 yd3 ) and Page 736 (20 yd3 ), which have been operating in the Tunçbilek open cast coal mine of Turkish Coal Enterprises (TKI) in Turkey. Research methodology encompasses four main stages: (i) obtaining the input data and analysis; (ii) fitting probability distribution to failures of draglines; (iii) estimating model parameters; (iv) making future projections and suggestions for developing modified preventive maintenance plans and availability predictions. Monthly maintenance records, operating hours and mechanical and electrical failure hours between 1998 and 2009 were acquired from the company. The number of mechanical and electrical failures is treated as a non-stationary Weibull process with intensity function of the failure rate. Then, the operating hours with 90 percent reliability for a given time period are evaluated in order to predict availability of the draglines. Also, maintenance hours per each breakdown are plotted and duration of breakdown throughout the years is analysed. Moreover, the expected number of failures for a given period of time is computed for planning the maintenance. The results indicated that Page 736 is more reliable than the Marion 7820 model.
Citation Formats
N. Demirel and H. Ş. Düzgün, “Reliability Modeling of Draglines for Availability Estimation and Maintenance Planning ,” presented at the 8th International Mineral Processing Seminar, Antofagasta, Şili, 4 - 09 Kasım 2009, 2009, Accessed: 00, 2021. [Online]. Available: