The Reliability and Maintainability Analysis of Pneumatic System of Rotary Drilling Machines

Abstract

In any blasthole drilling the bottom of the blasthole must be kept clean by evacuating drill cuttings or it flushing as soon as they appear to ensure efficient drilling. If it is not done well, a large quantity of energy will be consumed in regrinding with the consequent wear on drill bit and decrease penetration, apart from the risk of jamming. Therefore, research on reliability and probability of safe operation of pneumatic system of drilling machines is of prime importance to ensure safe drilling operations. In this paper, reliability of this system was modeled and analyzed. To doing this research, drilling machines in Sarcheshmeh Copper Mine in Iran have been selected for data collection and analysis. After reliability modeling of pneumatic system, maintenance scheduling has been presented based on different reliability levels. There were four rotary drilling machines in this mine (named A, B, C and D). Results showed that after about 7 h drilling of machines A and B, and after 103 and 44 h drilling of machines C and D respectively, noticeably the reliability of pneumatic system reached to 80 %. As a result, machines C and D have more reliable pneumatic systems in comparison to machines A and B and checking and servicing of pneumatic system before these time was essential. Also, maintainability analysis showed that more failures of pneumatic system of machines A, B, C and D will be noticeably repaired at about 28, 34, 6 and 9 h.