Evaluating different maintenance management strategies
Common maintenance management strategies
Outlined below are the more widely used maintenance management strategies, as well as their pros and cons and situations when they are best applied. Typically we see plants employing either run-to-failure (only fix after a breakdown) or preventive maintenance (on a predetermined schedule). However, depending on the value of the asset or its criticality in the plant’s operations, we may see this strategy escalated to predictive or even RCM-based maintenance.
Run-to-failure (breakdown maintenance)
What is run-to-failure maintenance?
In run-to-failure maintenance, assets are deliberately allowed to operate until they break down, at which point maintenance is performed. No maintenance is performed before then. A plan is in place ahead of failure, so the asset can be fixed without causing production issues.
Advantages of run-to-failure maintenance
Advantages of run-to-failure maintenance include:
- Minimal time spent planning and maintaining
- The simplicity of implementation
Disadvantages of run-to-failure maintenance
Disadvantages of run-to-failure maintenance include:
- Unpredictability and inconsistency of maintenance tasks and scheduling
- Higher maintenance and inventory costs
When to use run-to-failure maintenance
Use when the total cost of repairs after breakdown is less than the cost of performing maintenance beforehand. Use for redundant, non-critical assets that pose no safety risks. Equipment is fixed until it costs less to replace it.
Requires an understanding of how an asset might break and consequences. An example is the plan for a light bulb. The bulb operates until failure and is then fixed.
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Preventive (scheduled) maintenance (PM)
What is preventive maintenance?
Preventive maintenance is maintenance regularly performed on an asset to reduce the likelihood of it failing. It is performed while the asset is still working so that it doesn’t break unexpectedly. It is scheduled on a time or usage based trigger.
Advantages of preventive maintenance
Advantages of preventive maintenance include:
- Lower overhead costs, time commitments, production delays and accidents compared to unplanned maintenance
- Less expensive investments in technology, labour and data analysis compared to more complex systems
Disadvantages of preventive maintenance
Disadvantages of preventive maintenance include:
- Investing more time and resources in the planning stage compared to less complex systems
- The risk of conducting too much or too little maintenance and limiting efficiency across an operation
When to use preventive maintenance
Preventive maintenance should be used on assets that have a critical operational function, failure modes that can be prevented with regular maintenance and have a likelihood of failure that increases with time or use. An example of this strategy is scheduling maintenance for a conveyor belt on the first Monday of every month or after every 500 hours of operation.
Predictive maintenance (PdM)
What is predictive maintenance?
Predictive maintenance aims to predict when asset failure might occur and prevents the failure by scheduling maintenance. It keeps maintenance frequency low and reliability high. Possible failure is identified with monitoring equipment linked to software or through visual inspections.
Advantages of predictive maintenance
Advantages of predictive maintenance include:
- Cost savings on labour
- Higher production rates
- More insight into the performance and potential issues of assets
Disadvantages of predictive maintenance
Disadvantages of predictive maintenance include:
- A more costly upfront investment in technology, labour and skill
- Not all assets can be cost-effectively maintained using preventive maintenance
When to use predictive maintenance
Use predictive maintenance on assets that have a critical operational function and that have failure modes that can be cost-effectively predicted with regular monitoring. An example includes being able to monitor if a conveyor belt drops below a certain speed, which will trigger a work order.
Reliability centred maintenance (RCM)
What is reliability centred maintenance?
Reliability centred maintenance is an in-depth, highly involved process that seeks to analyze all the possible failure modes for each piece of equipment, and customize a maintenance strategy for each individual machine.
Advantages of reliability centred maintenance
The advantages of implementing reliability centred maintenance include:
- Increased equipment availability
- Reduction in costs for maintenance and resources
Disadvantages of reliability centred maintenance
Disadvantages of reliability centred maintenance include:
- It is often considered too complex and costly for many facilities to implement with the exception of large, experienced, enterprise-level organizations
When to use reliability centred maintenance
Reliability centred maintenance should be used on critical assets with identifiable failure modes that affect system function and can be controlled. It should be used after mastering other maintenance strategies and when facilities can invest required time, money and resources to implement.