# New Method to Study the Effectiveness of Mining Equipment: A Case Study of Surface Drilling Rigs
## 4 Discussion  
The development of the OMEE method to study the effectiveness of drilling rig is based on four steps: (i) acting, collecting information and data, (ii) observing, analyzing and reporting data, (iii) evaluating, evaluating and reviewing the process, and (iv) planning, identifying issues and suggesting solutions. This approach aligns with the methodology proposed in previous research [48]. The list of selected KPIs should assist in measuring the drilling rig performance behavior [49] and, subsequently, develop an appropriate method to analyze the mining process, identify poor performance and estimate improvement potential. To this end, the selected KPIs adhere to known recommendations [50], i.e., they are (1) correlated with the strategic aims, (2) significant and effective in representing and explaining the process, and (3) reliable, comprehensive, consistent and comparable. In this regard, the KPIs implemented allow us to determine the real-time performance of the equipment with a high degree of conformity. The availability rate emerges as a critical parameter for analyzing the effectiveness of the maintenance policy. Results show that the mechanical availability rate, in both mines, ranges from 94.4% to 99.5% of the total hours, which means that the breakdown hours are from 5.6% to 0.5% of the total hours. On the other hand, the technical availability rate is from 83.2% to 91.8% of the total hours. These results determine that the maintenance strategy developed is reliable and works optimally, in accordance with some previous research that emphasizes how an accurate maintenance program can improve availability [42; 44; 45]. While other authors mention that the drilling rig equipment suffers due to its hard-working conditions, accelerating degradation [33], this study has determined that an appropriate scheduled maintenance strategy, accounting for approximately 15% of the total hours, plays a vital role in minimizing the breakdowns hours, around 5% of the total hours, minimizing the continuous degradation of the drilling rig equipment throughout its operating life. This underscores the importance of a preventive and predictive culture to anticipate failures and improve availability [38; 39]. The utilization rate stands as a crucial parameter to determine how the management strategy is working. Results determine that the utilization rate is different in both mines. Mine 1 has a utilization rate with a minimum value of 88.5% and a maximum value of 94.1% of the available hours, except for year 7 when the availability rate was 65.8% due to market conditions, power station did not purchase coal. On the other hand, the utilization rate in Mine 2 ranges between 77.6% and 53% of the available hours, with a trend of continuously descending throughout its operating life, which implies important deviations in comparison with Mine 1. After analyzing the results, it has been found that the management strategy developed in Mine 2 was inadequate. The idle hours were continuously increasing throughout its operating life, which means that the management strategy, the operating management, and the short-term planning were inaccurate. As noted by [PERSON] et al. [51], equipment selection is one of the most challenging elements in the mining industry, especially in matching the correct number of mining equipment required to perform. In this case, the short-term management strategy of Mine 2 was inappropriate, with an incorrect number of drilling rig equipment to develop their functions, which led to a negative impact on the mining operation's effectiveness. On the other hand, results obtained from Mine 1 can be considered appropriate from the management strategy, the operating management, and the short-term planning point of view. Most of the rock drilled and blasted is sandstone, obtaining a drilling capacity between 32 and 42 m/Ho with the top hammer HL1000. The average production rate calculated is 37.12 m/Ho, which means that the drilling rig equipment is usually performing properly.