According to Wikipedia, OEE stands for Overall Equipment Effectiveness, and it refers to a metric that represents the efficiency of using machinery in comparison with the maximum possible efficiency, where the latter is calculated during the planned hours; OEE is expressed in percent: OEE = Availability x Performance x Quality.
Availability indicates the ratio of operating time to the time intended for operation (planned time – downtime divided by planned time) and in mining equipment, it means the loss of time because of failures, changeover, or waiting periods (for instance, for refuelling, for materials, or because of congestion).
The performance (or speed or throughput) is the comparison of output achieved in relation to the maximum output possible in that period of operation – in haul trucks, the performance ratio is expressed as the actual tonnage moved per hour divided by the maximum tonnage per hour considering the cycle time and payload capacity. Quality is measured in terms of the percentage of output that meets specifications (good units divided by total units produced); in mining operations, this means good tonnes loaded/dumped, proper sizes of materials, or re-handled materials.
In terms of mathematics, OEE can be determined from the following formula based on the number of productions: OEE = (Good Count × Ideal Cycle Time) / Planned Production Time, which simplifies to Availability × Performance × Quality multiplication, where each sub-element can be represented in its standard formula. With regard to the fleet application, the definition of each sub-factor can be modified, such as Availability defined for shifts or days, Performance using ideal speed calculation using the cycle time method or engine hours to tonnes conversion, or Quality using load accuracy, fragmentation, and rehandling percentage.
OEE serves as both a diagnosis and a priority setting instrument for managers since, due to its segmentation of total efficiency into three distinct types, it highlights areas where the key reasons for inefficiency exist (e.g., if Availability score is low, then work needs to be done on improving reliability and maintenance; if the Performance score is low, then issues regarding cycle time, routing, or operator efficiency need attention; and finally, if the Quality score is low, the issue lies either in loading or the quality of primary crusher feed).
OEE findings must be systematically analysed and acted upon to ensure progress: measure current OEE levels, establish specific goals for weak OEE factors, implement changes (such as proactive maintenance schedules, cycle time training, better dispatch policies, or load weighing automation), assess the effect of the change on OEE sub-factors and OEE itself, and apply proven techniques enterprise-wide. Cutting-edge usage of OEE in mining involves using OEE in conjunction with other methods (e.g., AHP-weighted OEE or fleet management modeling) to prioritize initiatives based on their economic benefits and modifying OEE formulas to consider differences within the mining fleet.
In the context of OEE use within mining fleets, care should be taken to maintain consistent definitions, collect reliable data (through telemetry, weight on loads, maintenance records, and shift work reports), and have appropriate governance to mitigate gaming of the measure; when done properly, OEE will become both an indicator of performance and a source of high impact areas for improvement.
