For any commercial fleet, vehicle and equipment availability and productivity is essential. Consequently, a carefully managed asset maintenance program is a must to ensure uptime and operational efficiency, and to help control costs. The maintenance strategy a fleet chooses can have significant financial consequences.
There are five basic types of maintenance strategies, each of which is differentiated by the nature of the tasks.
- Preventive (aka Planned) Maintenance (PM)
This is maintenance activity that takes place before something breaks so a fleet doesn’t incur vehicle/equipment downtime. It is almost always cheaper to do this than to wait for failure.
- Reactive Maintenance (RM)
This maintenance activity, as the name implies, is a reaction to asset failure after it occurs. Sometimes, however, waiting for a vehicle or piece of equipment to fail is the best thing to do. This will be explained later.
- Predictive Maintenance (PdM)
This maintenance strategy is based on specific information about the asset that is a reliable predictor of imminent failure, allowing maintenance to be planned before the failure occurs. Monitoring for future failure can include, among other things, oil analysis, vibration analysis and thermal analysis.
Condition Based Maintenance (CBM)
This is often used synonymously with predictive maintenance, however, there is a distinction. CBM is driven from real-time data gathered from sensors and other devices that measure specific conditions against known parameters of failure so that action can be taken in advance.
Reliability Centered Maintenance (RCM)
This maintenance strategy has a much broader scope, often incorporating all of the other strategies. RCM has been referred to as a process to establish the safe minimum levels of maintenance.
RCM begins with answering seven questions about the asset:
1. What are the functions and associated performance standards of the asset in its present operating context?
2. In what ways does it fail to fulfill its functions?
3. What causes each functional failure?
4. What happens when each failure occurs?
5. In what way does each failure matter?
6. What can be done to prevent each failure?
7. What should be done if a suitable preventive task cannot be found?
RCM is a complete engineering approach designed to do whatever it takes to promote the greatest level of vehicle/equipment reliability with the least investment of maintenance cost.
Decision Guidelines
Here are some general guidelines for choosing a particular maintenance strategy.
PM – Detailed job plans will need to be developed that spell out the maintenance tasks and the time intervals for each to keep the asset up and running. There should also be a means to capture the conditions found at each inspection. This is usually done with a PM work order and captured by the computerized maintenance management system (CMMS) for later analysis.
RM – This only works if the vehicle/equipment cannot be easily and or cheaply repaired. If it is cheaper to replace than to repair, use reactive maintenance.
PdM – This requires an investment either in analytical equipment and user training or contractors to do the analysis. The decision depends on the specific situation.
CBM – This is considered a good strategy overall, depending on the type of equipment, but it is also good way to minimize energy expense. CBM usually requires an investment in a remote data gathering system and user training.
RCM – This is a great maintenance strategy and considered the most cost effective overall. As was previously mentioned, RCM may encompass all of the other strategies, depending on the asset and the available resources.
Carefully weighing the pros and cons of each of these maintenance strategies can help a fleet determine which is most appropriate for its operation. Each strategy will incur different costs with regard to labor, wrench time, asset downtime, replacement parts, expedited parts, maintenance materials and supplies, etc.
Keep in mind that the time and expense of repairing a breakdown – which is reactive and unplanned – is always greater than the cost of the proactive maintenance, planned and completed in advance, that would have prevented the breakdown in the first place.
The overall objective is to invest money into the appropriate maintenance strategy that will result in higher asset reliability and availability. Doing so will help reduce unplanned expenses, decrease operating costs and increase operational efficiencies.
Steve Mueller is director of operations for Daniel Penn Associates (www.danielpenn.com), a management consulting firm with a proven track record of helping clients improve operating and management performance, and drive down the costs of the supply chain. He has more than 20 years of hands-on business management consulting experience, covering a wide range of industries, addressing virtually all business processes from service to manufacturing, involving all levels of management from CEOs to supervisors.