# New Method to Study the Effectiveness of Mining Equipment: A Case Study of Surface Drilling Rigs
## 3 Results
### Availability Rate  
The influence of scheduled maintenance programs on mining equipment effectiveness and availability has been widely proven. Appropriate maintenance policies should be developed to improve safe conditions, reliability, availability and effectiveness, avoiding unexpected failures and breakdowns. For this reason, the study divides the analysis of the availability rate into two elements, technical and mechanical availability rate. This approach allows us to assess the availability rate in a complementary and interrelating way, examining the breakdown hours' evolution over time and the influence of scheduled maintenance programs on breakdown hours. It allows for potential modification to maintenance policies in case of an increase in breakdown hours. As previously outlined, the technical and mechanical availability rates have been calculated using the method OMEE. Table 8 shows the results of the technical and mechanical availability rates for both drilling rig fleets used in the two different open-pit mines. Additionally, Figures 3 and 4 show how the technical and mechanical availability rates evolved over 10 years. These graphs present a comparison between the technical and mechanical availability rates of the two drilling rig fleets performing in both mines. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Year** & **Ht** & **Ho** & **Hb** & **Hm** & **Hi** & **Hmv** & **Hot** \\ \hline
4 & 5470.0 & 3367.0 & 260.5 & 871.0 & 507.5 & 459.0 & 5.0 \\
5 & 8125.0 & 4555.0 & 434.0 & 1367.0 & 1330.0 & 444.0 & 0.0 \\
6 & 12,479.0 & 6531.0 & 404.5 & 2089.0 & 2992.5 & 462.0 & 0.0 \\
7 & 13,395.0 & 6870.0 & 407.0 & 2019.5 & 3771.5 & 327.0 & 0.0 \\
8 & 20,367.0 & 9923.0 & 789.0 & 2003.0 & 7095.0 & 557.0 & 0.0 \\
9 & 19,071.0 & 9927.5 & 196.0 & 1805.0 & 6280.5 & 552.0 & 310.0 \\
10 & 20,259.0 & 9737.0 & 96.0 & 1803.0 & 7772.0 & 676.0 & 175.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Mine 2. Drilling rig performance, temporal KPIs (h). \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Year** & **Production (m)** & **Fuel (L)** & **m/Ho** & **L/m** \\ \hline
4 & 114,309.0 & 133,550.0 & 33.95 & 1.17 \\
5 & 154,811.0 & 187,961.0 & 33.99 & 1.21 \\
6 & 220,922.0 & 241,913.0 & 33.83 & 1.10 \\
7 & 220,186.0 & 235,648.0 & 32.05 & 1.07 \\
8 & 296,665.0 & 303,908.0 & 29.90 & 1.02 \\
9 & 280,981.0 & 309,533.0 & 28.30 & 1.10 \\
10 & 286,633.0 & 282,746.0 & 29.44 & 0.99 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Mine 2. Drilling rig performance. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Year** & **Production (m)** & **Fuel (L)** & **m/Ho** & **L/m** \\ \hline
1 & 437,552.0 & 351,323.0 & 38.23 & 0.80 \\
2 & 487,677.0 & 402,765.0 & 38.43 & 0.83 \\
3 & 561,192.0 & 419,260.0 & 38.94 & 0.75 \\
4 & 531,515.0 & 470,832.0 & 36.05 & 0.89 \\
5 & 512,875.0 & 473,423.0 & 37.27 & 0.92 \\
6 & 510,783.0 & 446,725.0 & 38.27 & 0.87 \\
7 & 364,763.0 & 372,264.0 & 36.50 & 1.02 \\
8 & 493,998.0 & 496,871.0 & 37.68 & 1.01 \\
9 & 587,560.0 & 559,002.0 & 36.53 & 0.95 \\
10 & 707,969.0 & 723,389.0 & 36.61 & 1.02 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Mine 1. Drilling rig performance. As can be seen in Figure 3, the scheduled maintenance strategy accounts for approximately 15% of the total hours. Thus, this strategy improves mechanical availability by roughly 95%, as shown in Figure 4, which implies that breakdowns are around 5% of the total performance hours. Therefore, the evolution of mechanical availability remains at a similar range, without a remarkable decrease, and it can be stated that the scheduled maintenance strategy is adequate.