Quality engineering tools in analysis of failure of longwall mining complex

Downtimes caused by machine failures translate into a loss of effectiveness in the mining process. The main task of maintenance teams in hard coal mines is to ensure the uninterrupted work of the machines used. A measurable effect of these activities should be reducing machine maintenance and, as a consequence, reducing the costs of coal mining; i.e., a mine’s operating costs. In the present article, two longwall mining machines have been analyzed: a cutter-loader and a plow. The analysis was based on one of the quality engineering tools – the Pareto–Lorenz diagram. This tool allows for grouping the causes of breakdowns and establishing which of them are the most important and should be removed first. The analysis has demonstrated the significance of machine selection and its adjustment to the existing geological-mining conditions. Improper selection results in increased energy consumption in the mining process, premature wear, or prolonged downtimes caused by breakdowns.