Lifecycle Management

Influencing equipment performance through maintenance metrics

Successful sites use key measurements to improve availability

The primary deliverable for any mine maintenance organization is available hours that the operations department can use to meet its production goals. Performance in this area is reported in terms of availability. Virtually every mine measures and tracks some form of availability. It’s a key measurement by which mine management quantifies the performance of its equipment fleet, and it provides the basis for identifying equipment needs.

Three critical factors affect equipment availability: The design of the product, the application/operation in which it is used, and the maintenance it receives during its time in service. Of those three, maintenance offers the greatest opportunity for improvement.

“Maintenance is the factor that offers mining companies the best opportunity to influence and control the performance and availability of their equipment,” say Abelardo Flores and Jim McCaherty, co-authors of “Performance Metrics for Mobile Mining Equipment,” a Caterpillar guideline created to assist mining equipment users in the definition and use of uniform criteria for the evaluation of product and project performance. “The end-user has enormous ability to influence performance through maintenance practices.”


Maintenance and repair process implementation and resource selection—including facilities, tooling, support equipment, lubricants and contamination control practices—all have a direct bearing on the final results owners receive from the equipment they purchase.

The most successful mining equipment management operations realize that maintenance goes well beyond draining oil, changing filters and performing the basic routines recommended by the manufacturer. “In addition to preventive maintenance, successful mines also incorporate predictive and corrective procedures in order to be fully effective,” says Flores. “The term ‘equipment management’ implies a cohesive effort on the part of the entire organization—not just those routine activities performed by the maintenance department.”

Beyond having predictive, cohesive maintenance practices, the focus of the Caterpillar® document is on one key factor: Measurement. “It’s true that the availability of your equipment depends on the performance of proper maintenance and repair,” explains Patrick Mohrman, Caterpillar Global Mining site support manager. “In order to understand if the maintenance and repair are being performed correctly, you need to measure. We at Caterpillar want mine sites to know how important this is. If you’re not already measuring, you should be thinking about measuring.”

Machine maintenance is not an option. “In order to keep equipment working at peak performance, it must be taken out of service for maintenance and repairs,” Mohrman says. “However, when equipment is down for service or repairs, it’s not productive, so it’s not generating revenue. The successful equipment manager needs to manage this downtime effectively and efficiently in order to optimize the time the equipment is productive. The ultimate goal is to improve availability.”


In order to quantify equipment performance, performance criteria must be put in place. The following hold true for most activities, including the management of mining equipment:

  • You cannot manage what you cannot control
  • You cannot control what you cannot measure
  • You cannot (or at least should not) measure without a target
  • Without a target, you cannot improve

“Management without metrics is, in reality, management by intuition,” says McCaherty.

Caterpillar recommends benchmarking—a process to identify best practices—to gauge performance relative to the competition or to monitor progress toward a specific set of objectives. The benchmarking process aids in the identification of weak areas, poor practices and opportunities for improvement. It’s a systematic, ongoing, continuous improvement process that requires a long-term commitment.

The results that come out of the benchmarking process may be called standards, measurements, metrics or Key Performance Indicators (KPIs). They quantify best practices for an operation and could be:

  • Operational (payload management, delays in load times, truck exchange times, production, cost per ton, etc.)
  • Application-related (grade/grade variation, rolling resistance, haul road maintenance, traffic flow, etc.)
  • Maintenance-related (availability, utilization, etc.)

The benchmarks that Caterpillar has established for equipment management were designed to answer these questions:

  1. How are we? Where do we stand today?
  2. How much effort have we invested in getting where we are?
  3. Is our situation the result of planned work?
  4. What are the locations and frequency of our “pain”?
  5. Is our situation stable? Is it sustainable?
  6. Are we using “failures” as an information source?
  7. Can we forecast the future?

“No matter how good a piece of equipment is, how good the maintenance is, or how easy the application is, sooner or later there will be problems,” says McCaherty. “What distinguishes the successful site from the less successful one is the organization that is in place, and how it deals with problems when they arise. Rather than ask, ‘How long will it be down?’ the knowledgeable equipment manager asks, ‘Why did it go down and what can we do to prevent this from happening again?’”

Unscheduled shutdowns (downtime) are the enemy of equipment management. Unscheduled shutdowns may be due to an equipment failure that can be solved with a technical solution; however, they may also be the result of a failure of the equipment management organization, whose responsibility it is to avoid equipment problems and failures. Either situation can be improved through the use of performance metrics.



Although their calculation methods may vary, the majority of mines measure and report availability. While useful for providing a historical view of the past and present health of an equipment fleet, traditional availability measurements fail to give the user a clear insight into why things are the way they are, what needs to be done to ensure a healthy situation remains healthy, or how a problem situation can be resolved.

Mines also frequently monitor and report a number of other parameters that provide information—but little else that could be viewed as either predictive (allowing the mine to be proactive) or corrective (enhancing the mine’s ability to develop action plans).

“Mines typically collect mountains of data and compile reports,” says Flores. “But oftentimes they don’t take advantage of that data to improve the operation—turning the data into information for use as ‘management tools’ to determine why a condition exists, what can be done to reverse a bad trend, or how to sustain a good situation.”

What do mining companies really want and need? “Reports that identify equipment problems—both current and future—document equipment health, and eliminate surprises,” answers McCaherty. “Reports should also help set priorities for problem management and continuous improvement activities that help mine sites focus their efforts and resources on the most significant issues affecting performance.”

Reports should be informational and also possess analytical, interpretive, predictive and corrective characteristics—stimulating thought instead of simply reporting results, says Flores. They also should be:

  • Regular — typically monthly
  • Timely — so management isn’t using old information
  • Visual — so they are easy to understand at a glance
  • Concise — because bigger is not always better
  • Action-oriented — driven by functional objectives
  • Easily understood — to encourage application and maintenance

“One very good rule of thumb is ‘Don’t generate more questions than you can answer,’” says McCaherty. “If you think of reporting as ‘applying what you know to what you want to know,’ the task becomes much simpler.”


Caterpillar’s experts developed a collection of “top tier” performance metrics called Key Performance Indicators (KPIs) that give mine managers a “cockpit view” of what they need to assess their situation.

“In the same sense that an airline pilot needs only a handful of the hundred or so sources of information he has at his disposal to safely land a plane, these KPIs are a small fraction of the performance metrics available,” says Flores. “Of course, there must be sufficient secondary information to permit the mine manager to proactively take necessary action if a problem is detected.”

Caterpillar has invested a great deal of time, energy and resources in developing these key metrics. “First we worked to determine the data available at most sites that could be developed into information and metrics that represent and correlate to fleet performance. At that point we were able to interpret what these metrics mean relative to site performance and to understand how they interact with each other. Finally, we devised a presentation format that enables the equipment manager to quickly and easily recognize critical issues,” says McCaherty. “We’re very comfortable with using these KPIs to quantify and trend equipment health.”

The top tier metrics identified as KPIs are:

  • Mean Time Between Shutdowns. Mean Time Between Shutdowns (MTBS) quantifies the average frequency of machine stoppages. It combines the effects of inherent machine reliability and the effectiveness of the equipment management organization in its ability to influence that reliability through problem avoidance. MTBS is the single most important measure of equipment maintenance management performance.
  • Mean Time to Repair. Mean Time to Repair (MTTR) quantifies the average duration of machine stoppages (repair turnaround time), i.e., how quickly or slowly a machine is returned to service once a downtime incident occurs. MTTR combines the effects of machine maintainability/serviceability and the efficiency of the equipment management organization in delivering rapid remedial action in the execution of needed repairs.
  • Availability Index. The ratio of MTBS (average shutdown frequency) to the sum of MTBS and MTTR (average shutdown duration), expressed as a percentage, is defined as the Availability Index. Unlike most traditional availability measures, the Availability Index allows the equipment manager to break down availability into its elements, i.e., frequency and duration of downtime events, and take appropriate remedial action.
  • Percent Scheduled Downtime. The percentage of total downtime hours performed in a given period that have been planned and scheduled. By monitoring the percentage of downtime that has been planned and subsequently scheduled, the organization can assess its effectiveness and efficiency in defect detection and repair planning, scheduling and execution. A high percentage of scheduled downtime is indicative of a proactive organization.
  • Maintenance Ratio. The dimensionless ratio of maintenance and repair man-hours to machine operating hours. It indicates the amount of effort required to keep equipment in service as well as the efficiency with which labor is deployed and the effectiveness of the workforce.
  • Asset Utilization. The proportion of time that a machine is operating (operating hours) divided by the total calendar time in the period, expressed as a percentage. Asset Utilization can be used in conjunction with Maintenance Ratio to forecast manpower and resource requirements. Many mines schedule their equipment for use 24 hours a day, seven days a week. Maintenance must work with Operations to find windows of opportunity for maintenance and repairs.
  • Top Problems. The distribution of problems affecting a fleet of equipment ranked in terms of MTBS, MTTR, impact on Availability and Costs. All mining companies have limited resources; the most successful operations use a Pareto analysis to identify top problems to obtain a clear understanding of the key issues they face, and establish priorities in order to focus their efforts and allocate resources.


Performance Metric. A term used to describe the outcome of any process used to collect, analyze, interpret and present quantitative data. It enables performance against a pre-defined target or benchmark to be monitored.

Key Performance Indicator (KPI). A top-level performance metric. KPIs may vary from site to site, by product, application or perspective. All KPIs are performance metrics—but performance metrics are not always KPIs.

Target. A desired goal; a standard by which a performance metric can be measured or judged. May vary by product, application or specific site.

Benchmark. A world-class performance standard relative to a specific performance metric; represents and quantifies best practice of an operation or of specific functions within that operation according to a specific performance metric.

Shutdown/stoppage. A event that takes a machine out of service. May be scheduled or unscheduled and includes all types of maintenance and repair activities except daily lubes, refueling and inspections executed during lube or refueling activities.



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