Mining Equipment Reliability
Table of Contents:
Each year, a vast sum of money is spent to produce various types of equipment for use by the mining industry around the globe, and this expenditure is increasing quite rapidly. For example, in 2004, the United States mining equipment manufacturers shipped approximately $ 1.4 billion worth of goods, and a year later that figure jumped to around $2 billion . Nowadays, the world economy is forcing mining companies to modernize their operations through increased automation and mechanization.
Thus, as equipment used in mines is becoming more complex and sophisticated, its cost is increasing rapidly. This in turn makes it quite cost-ineffective for having standby units. To meet production targets, mining companies around the globe are increasingly demanding better equipment reliability. Reliability is a very good indicator of overall equipment condition and is expressed as the probability that a piece of equipment will perform its function satisfactorily for the desired period of time when used as per stated conditions. However, it is to be noted that in the industrial sector reliability is often expressed in terms of mean time between failures.
This chapter presents various important aspects of mining equipment reliability.
Reasons for Improving Mining Equipment Reliability and Factors Impacting Mining System Reliability
There are many reasons to improve reliability of mining equipment and some of these are as follows [2,3]: 
There are many factors that, directly or indirectly, impact mining equipment/system
reliability. Thirteen of these factors are as follows [2,3]:
Useful Reliability-Related Measures for Mining Equipment
There are many mining equipment, directly or indirectly, reliability-related measures.
Five of these measures considered quite useful are presented below [2,3].
Measure I: Mean Time Between Failures
This is defined by
MTBF is the mean time between failures.
F is the number of failures.
H, is the total hours.
Hd is the downtime expressed in hours.
Hs is the standby hours.
Measure II: Production Efficiency
This measure may simply be described as the ratio of actual output from a piece of equipment/machine (which satisfies the required quality standards) to its rated output during the period it is operational. Nonetheless, production efficiency is defined by
Ep is the production efficiency.
Pa is the actual production.
Cr is the rated capacity expressed in units per hour.
Measure III: Utilization
This is expressed by
UT is the utilization.
Measure IV: Overall Equipment Effectiveness
This is defined by
Eoe is the overall equipment effectiveness.
A Vme is the mining equipment/system availability.
Measure V: Availability
This is simply the proportion of time the equipment/system is able to be used for its intended purpose and is defined by