IMPACT OF DOWNTIME PATTERN ON MINING MACHINERY EFFICIENCY

In this paper, problem of mining machinery efficiency is considered through impact of different types of downtimes. New methodology is suggested based on comparison impact of mechanical and technological mining machinery time in fault (M-t, T-t) and mechanical and technological mining machinery downtime frequencies (M-f, T-f) on machine work done (W). Benchmarking analysis is conducted by pairing variables M-t-W, T-t-W, M-f-W and T-f-W, and determining relationships between observed variables. By comparing the increment of the cumulative downtime curve with the cumulative curve of the machine's operating volume, it can be assessed whether the observed downtime develops a concave or convex character of the operating volume cumulative curve, in respect to significant losses. Results indicate that the relationship between cumulative downtime curve and cumulative work done curve can successfully serve as a parameter for evaluating the impact of specific downtime on the efficiency of the machine. A multi-criteria analysis, namely, an analysis of the criteria - frequency and time spent in downtime for each of the observed causes of downtime, clearly determines the critical pattern of downtime on the efficiency of the observed machine.