Preventative Maintenance – there are very few terms that have become as embedded in the restaurant facilities industry more than “Preventative” or “Preventive Maintenance.” Whether we’re speaking of HVACR equipment or parking lots, we all have resigned ourselves to the “fact” that it is needed, even though the evidence to support the need is seemingly anecdotal. This is not to say that our resignation is unfounded; up until a few years ago, however, it was scarcely documented.
When you think about the phrase “preventative maintenance” do you ever ask yourself, what exactly am I preventing? Am I truly preventing or reducing the chance of a catastrophic failure? Am I truly extending the useful life of my equipment or asset? Or am I just paying money for someone to tell me that I have to spend more money? Would I be better off just letting the darn thing run and not letting anybody touch it?
Does Preventative Maintenance Mitigate or “Prevent” Failures?
I wrote an article a few years back entitled “When Does a PM Program Make Sense?” In that article, I attempted to tackle the age-old question of how much does a PM program actually mitigate in regards to failures of electro-mechanical components and equipment. The results were not astounding, but many would consider the percentage of failures mitigated by a properly executed maintenance program to be at the least substantial enough to entertain the idea. We found that at least 14% of component failure patterns could be mitigated by a properly executed maintenance program. To recap that article briefly, there are 6 component failure patterns that contribute to the demise of electro-mechanical component failures as follows:
We found that there are 3 failure patterns that can be directly addressed by implementing a maintenance program:
Age Related - 2%: a maintenance program can help facilitate the identification of aging parts and allow us to have them replaced prior to total failure.
Fatigue-Related - 5%: components and equipment can demonstrate premature failures due to fatigue. An example would be a compressor for an HVAC or refrigeration system operating for abnormally longer periods due to an impacted condenser coil. Because heat rejection is impaired, the system is required to run longer and harder which could contribute to the early demise of the compressor and its internal components.
Condition-Related – 7%: the operational conditions and environment in which a structure, system or component is operating in could affect a percentage of failures within that system. Inclement weather patterns, neighboring manufacturing activities and coastal regions are all examples of things we may consider to be condition-related attributes that could promote premature failure.
We must also realize that most components demonstrate what’s called a Failure Development Period or FDP. For instance, motor bearings will usually make some sort of audible warning prior to their total failure such as squeaking, screeching or grinding. The motor may be operational; however, it is demonstrating a failure development. This is something a regularly scheduled maintenance program would be able to identify prior to total failure at the worst possible time.
So, when does a PM program make sense? Two conditions must be met:
The component/equipment in question has an increasing failure rate. In other words, the failure rate of the component increases with time, thus implying the component is subject to the failure patterns outlined previously.
The overall cost of a preventive maintenance action is usually less than the overall cost of a corrective action. (Note: In the overall cost of a corrective action, one should include ancillary tangible and/or intangible costs such as downtime costs, loss of production costs, lawsuits over the failure of safety-critical items and loss of goodwill.)
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