# Fault Analysis of Shearer-Cutting Units Driven by Integrated Importance Measure
## 3 A Case Study of Cutting Units for MG400/930-WD Shearer
### Analysis of Key Failure Causes Based on IIM  
According to Table 4, the IIM of each bottom event can be evaluated by Equation (1). The IIM results of 20 bottom events are listed in Table 5 and Figure 5. IIM ranking results from the largest to the smallest: C19 > C17 > C18 > C12 > C1 > C5 > C10 > C4 > C3 > C8 > C20 > C9 > C11 > C14 > C15 > C16 > C7 > C6 > C13. Under the limited maintenance resources, the bottom events C19 (bearing wear), C17 (nonconformity of oil varieties or improper oil quantity), and C18 (cooling spray function failure) should be repaired as priorities.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Subsystem** & **Bottom Events** & **Failure Rate** & **Failure Times** & **Conditional Failure** & **Subsystem Failure Probability** & **Failure Probability** \\ \hline \multirow{6}{*}{Rocker arm} & C1 & \(1.10\times 10^{-6}\) & 39 & 0.475610 & 0.029804 & 0.014175 \\  & C2 & \(3.70\times 10^{-7}\) & 5 & 0.060976 & 0.029804 & 0.001817 \\  & C3 & \(6.00\times 10^{-7}\) & 3 & 0.036585 & 0.029804 & 0.001090 \\  & C4 & \(6.00\times 10^{-7}\) & 2 & 0.024390 & 0.029804 & 0.000727 \\  & C5 & \(8.00\times 10^{-7}\) & 33 & 0.402439 & 0.029804 & 0.011994 \\ \hline \multirow{6}{*}{Cutting motor} & C6 & \(1.20\times 10^{-6}\) & 14 & 0.170732 & 0.218441 & 0.037295 \\  & C7 & \(1.20\times 10^{-6}\) & 7 & 0.085366 & 0.218441 & 0.018647 \\  & C8 & \(5.80\times 10^{-7}\) & 50 & 0.609756 & 0.218441 & 0.133196 \\  & C9 & \(3.00\times 10^{-7}\) & 11 & 0.134146 & 0.218441 & 0.029303 \\ \hline \multirow{6}{*}{Cutting drum} & C10 & \(7.00\times 10^{-7}\) & 78 & 0.523490 & 0.112070 & 0.058667 \\  & C11 & \(1.75\times 10^{-7}\) & 1 & 0.00671 & 0.112070 & 0.000752 \\  & C12 & \(2.20\times 10^{-6}\) & 69 & 0.463087 & 0.112070 & 0.051898 \\  & C13 & \(1.50\times 10^{-8}\) & 1 & 0.006711 & 0.112070 & 0.000752 \\ \hline \multirow{6}{*}{Transmission} & C14 & \(1.20\times 10^{-7}\) & 21 & 0.115385 & 0.639686 & 0.073810 \\  & C15 & \(1.20\times 10^{-7}\) & 15 & 0.082418 & 0.639686 & 0.052721 \\ \cline{1-1}  & C16 & \(8.00\times 10^{-8}\) & 14 & 0.076923 & 0.639686 & 0.049207 \\ \cline{1-1}  & C17 & \(3.50\times 10^{-6}\) & 21 & 0.115385 & 0.639686 & 0.073810 \\ \cline{1-1}  & C18 & \(2.70\times 10^{-6}\) & 40 & 0.219780 & 0.639686 & 0.140590 \\ \cline{1-1}  & C19 & \(3.53\times 10^{-6}\) & 68 & 0.373626 & 0.639686 & 0.239004 \\ \cline{1-1}  & C20 & \(5.00\times 10^{-7}\) & 3 & 0.016484 & 0.639686 & 0.010544 \\ \hline \hline \end{tabular}
\end{table}
Table 4: The probability of failure of each fault event in the interception department.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Bottom Events** & **IIM** & **Bottom Events** & **IIM** \\ \hline C1 & \(3.99911\times 10^{-7}\) & C11 & \(6.36222\times 10^{-8}\) \\ C2 & \(1.34516\times 10^{-7}\) & C12 & \(7.99822\times 10^{-7}\) \\ C3 & \(2.18133\times 10^{-7}\) & C13 & \(5.45333\times 10^{-9}\) \\ C4 & \(2.18133\times 10^{-7}\) & C14 & \(4.36267\times 10^{-8}\) \\ C5 & \(2.90844\times 10^{-7}\) & C15 & \(4.36266\times 10^{-8}\) \\ C6 & \(7.83712\times 10^{-9}\) & C16 & \(2.90845\times 10^{-8}\) \\ C7 & \(1.59783\times 10^{-8}\) & C17 & \(1.27244\times 10^{-6}\) \\ C8 & \(2.10862\times 10^{-7}\) & C18 & \(9.81600\times 10^{-7}\) \\ C9 & \(1.09067\times 10^{-7}\) & C19 & \(1.28335\times 10^{-6}\) \\ C10 & \(2.54489\times 10^{-7}\) & C20 & \(1.81778\times 10^{-7}\) \\ \hline \hline \end{tabular}
\end{table}
Table 5: Integrated importance measure values of the bottom events.