Introduction
This article is a highly simplified overview of Equipment Maintenance Strategies. Its objective is to categorize the types of maintenance approaches for the lay person. Sometimes, explaining the basics using simple terminologies, initiates dialogues with others that are outside of our field of expertise. And as such improve collaboration between teams. How about making this accountant who somewhat controls the maintenance budget, understand what maintenance is really about? On the other hand, that same accountant can educate us on their work practices.
Definition of Maintenance
Equipment maintenance refers to the scheduled and routine actions conducted by certified equipment support professional to keep machinery and assets in good working condition. This includes inspections, repairs, part replacements, and even cleaning. Regular maintenance helps prevent unexpected breakdowns, prolongs equipment lifespan, and ensures efficient and safe operation across various industries.
Most of us have worked for profit-oriented companies and we tend to look at the material benefits of maintenance. Or rather the lack of thereof. No harm in that as profits generate prosperity and livelihoods. However, one of the primary objectives of maintenance should be the safety of workers and communities. As without safety, prosperity does not really matter.
Typically, equipment maintenance tasks fall under two main categories. Planned and Unplanned Maintenance. In total the 4 types of equipment maintenance strategies are covered in this article. This is illustrated in Diagram 1 below. Examples used in this article are on automobiles deemed a commodity that most of us own. And subsequently apply maintenance tasks on.
Zero Maintenance
This implies that no maintenance strategy is developed to manage equipment or assets. It is also called the “run to failure” approach. In essence, when an asset fails, we replace the entire asset with another similar one. A good example would be a kitchen appliance like a kettle. When it fails, it is often cheaper to replace it than to repair it. In this case, one is also subject to minor inconvenience as water can be boiled on a stove or barbecue.
Using the automobile as an example would mean that as soon as the automobile does not perform its primary function of driving, we replace it with another automobile. Expensive option except when the automobile is a rental or long-term lease. So, in essence, a zero-maintenance approach is more suited for cheaper commodities or low risk events.
Unplanned Corrective Maintenance
Corrective maintenance is applied to components that make up assets. An automobile for example, is made up of components such as the gearbox, drive train, engine, or even tires just to name of few. These components are themselves made up of sub-components and we can go deeper still. Corrective maintenance is applied when a component fails. We do not discard the automobile but chose rather to repair it. It is deemed the cheapest option. However, corrective maintenance is often related to unplanned failures. In other words, and as an example, your automobile alternator failed unexpectedly and left you stranded. Corrective maintenance is typically more expensive. In the same alternator example, you are now in the middle of nowhere and might need the assistance of a two truck and a taxi to get home.
Planned Preventive Maintenance
Moving into the planned side of maintenance. Now we put a little bit more thought in the maintenance strategy and try to be in control of failures rather than the other way round. Planned Preventive maintenance involves performing inspections or adjustments at specific intervals on the equipment. If an imminent failure is discovered, then a corrective maintenance task is initiated. The failure is addressed before it unexpectedly occurs and interrupts production down the road. It is also a very opportune time to work on the asset as it is already down for maintenance.
Bringing it to our automobile, this is the same as the required service every 6,000 km on the average automobile. The automobile will be sent to a repair shop and routine tasks will be performed. If an impending failure is discovered by the mechanic, it will be addressed during the service. Avoiding any unplanned failures between service intervals.
Planned Predictive Maintenance
Predictive Maintenance is somewhat a more sophisticated approach to equipment maintenance. It usually involves “non invasive” techniques that assess the condition of the asset. This is why it is also called Condition Monitoring. In the previously mentioned Preventive Maintenance strategy, one would take apart the equipment to inspect it. Sometimes, this physical intervention can cause more problems than solve any. It is also known as “failure induced maintenance”. Ever been a “wanna-be” mechanic on your own automobile only to find out that you caused more problems than if you had sent it to a certified mechanic?
Condition Monitoring will therefore involve tasks that do not take the equipment apart to evaluate its condition. These tasks measure specific physical or chemical parameters on the equipment. They include oil analysis, vibration analysis or infrared inspection just to name a few. They are very precise and can be done whilst the equipment is in operation. Hence with minimal impact to the production output. If an anomaly or impending failure is detected, a corrective maintenance task can be performed later. And in a planned and controlled manner again minimizing impact to production output.
Regarding our automobile, this can be related to diagnostics checks that are done continuously on the vehicle. One of the examples of automobile diagnostics that I found very useful, was a viscometer placed within the engine block. Continuous viscosity monitoring informs the driver exactly when an oil change is required. This feature doubled my service intervals. Rather than going to the mechanic indiscriminately every 6,000 kms, I could drive for up to 12,000 kms. Without any adverse effect on the engine’s integrity. In essence Predictive Maintenance is precise and reduces the amount of maintenance required. Hence reducing costs whilst increasing production output due to less interruptions.
Maintenance comes at a cost. Do it too frequently and more money than required is spent. Conversely, do it too infrequently and you are running a higher risk of failure. With the correct diagnostics, the maintenance task will be performed at the most economical time. Saving the company on spares costs, resource mobilization and impact to operations.
Conclusion
Equipment maintenance is somewhat an inevitable expense. However, the objective is to make the savings obtained from maintenance higher than that of the cost of maintenance. This should be like music to the ears of an accountant. Maintenance can be more or less sophisticated depending on the type chosen. However, sophistication does not equate to more costs. It all depends on the methodology used. More science applied to maintenance helps find the best strategies. This is where Reliability Engineering comes into the picture.
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