Reliability-centered maintenance: An extensive system that lacks real world applicability.
Manufacturer-suggested schedule: Ignores the benefits of experience within the actual operating context.
Purely estimated PM schedule: Enacting in response to breakdown/incentive, based on OEM schedule or approximations.
3 Elements of Preventative Maintenance
What tasks are necessary for PM?
Scheduling PMs to fit in with parts/tools availability and a production schedule
How frequently should you perform these tasks to optimize maintenance of that asset?
The necessary tasks can be determined by experienced maintenance personnel, or from following OEM guidelines. Likewise, collaborating with production schedules and parts/tools availability is simply a matter of good planning. The only thing left is to determine the frequency of these actions.
Asset Healthcare Model vs. RCM
Less cumbersome than RCM – designed to be used without detailed equipment knowledge
Covers entire equipment spectrum
Minimizes data re-entry
Can be implemented by hourly workforce with minimal guidance beyond initial training
RCM, in it’s many forms, is generally too unwieldy for real world application. Its use should be reserved for complex pieces of machinery with very involved maintenance requirements.
Stages to Implementing a PM Program
Develop your asset hierarchyCreating asset hierarchies has a twofold effect.
It allows for easy reference to and builds relationships between all maintainable assets
The process of going through assets and categorising them down to each maintainable component gives the operators a more thorough understanding of the individual machinery, right down to the component level. You might hear comments like, “I didn’t even know this thing HAD a washer – we never change it!”
Determine CriticalityThe importance of the component itself is ranked separately in the next phase. A rudimentary ranking system is shown below.
An alternative scale can be used, provided it ranks along similar lines.
Then rank the individual component as how it supports the process it is tied to.
The next step is to combine the two rankings for a table that looks like this:
Now that we have discussed the pros and cons of the various popular maintenance strategies and have started to define what is essentially a quickly deployed hybrid between complex strategies like RCM and simple PM schedules, we rank the assets on criticality of failure and the importance of the process they support. These tables can be combined into a quick reference for overall asset importance.
Determine Current Operating Condition of EquipmentThis goes hand-in-hand with the relative importance ranking principle established in Step 2. Old machinery that also has high criticality will need much more attention or possible replacement. Newer, less critical machinery can be given little attention.
Develop a Maintenance Strategy for each EquipmentThere are a wide variety of available maintenance strategies. A few are listed below. Assets with low criticality (eg. C5) can be maintained with a run-to-failure strategy. High criticality assets however, (eg. A2) should have either intensive PM schedules and inspections, or an investment into some kind of condition monitoring technology. Available strategies include:
Run to failure
Finalize Specific Maintenance ActivitiesAfter all the groundwork has been laid, the specific activities need to be decided on. What needs to be done for each weekly PM? For each monthly PM? Each strategy implies a different level of asset care, and its corresponding activities. PM’s will include largely inspections and possible repair. RCM and continuous monitoring involve a much more intensive set of activities like different tests and calibrations. Build out a plan for every asset including as many details as possible for each maintenance activity. This plan should be re-examined and changed at different intervals.