How do you choose the right maintenance strategy for your organization? Someone from the outside looking in might think the notion of choosing a maintenance strategy is as simple as choosing between ‘repair it’ or ‘replace it’, and that’s not entirely inaccurate. Beyond the surface, though, there are a number of different considerations that can have a long-term impact on a company’s bottom line and ultimate viability. Particularly when working with numerous or expensive essential assets that are subject to the continual wear-and-tear and eventual breakdown that plagues all machines, maintenance costs can take enormous bites out of revenue.
Fortunately, numerous maintenance strategies have evolved over the years, and technology allows us to apply new techniques using new models that were previously unheard of. Let’s review some of the more popular maintenance strategies:
This is the simplest strategy, sometimes referred to as ‘breakdown maintenance’. The premise is simple: Use something until it can no longer be used. Then, do what needs to be to repair it and get it back in action. If it can’t be repaired, replace it. There are some benefits when compared to other strategies, such as lower initial costs and reduced staff, as well as eliminating the need to plan. Of course, these benefits are usually negated in the long term by unplanned downtime, shortened life expectancy of assets, and a complete inability to predict breakdowns and maintenance needs. The only real viable reason for employing this strategy is an inability to afford the initial costs of any other strategy.
Preventative maintenance is performed while an asset is still operational in order to decrease the likelihood of failure. In this strategy, maintenance is performed according to a particular time or usage schedule. For instance, regular maintenance will be performed when this particular machine reaches 5,000 hours of uptime since the last maintenance. Predictive maintenance will typically keep equipment operating with greater efficiency and extend the lifetime of the asset compared to reactive maintenance, while also preventing unnecessary downtime. It does, however, require greater planning and man-power. Preventative maintenance is not a good choice for assets like circuit boards that can fail randomly regardless of maintenance. It is also not ideal for assets that do not serve a critical function and will not cause downtime in the event of a failure.
The purpose of predictive maintenance is to predict an imminent failure and perform maintenance before it occurs. This strategy requires some specific condition monitoring and will typically have a higher upfront cost due to the need to add sensors or other hardware, and will also require skilled personnel capable of anticipating failures based on the data points being monitored. Benefits include: the ability to prevent unnecessary downtime, and minimal time spent performing maintenance as it is only done when failure is imminent. Predictive maintenance is usually not a good option for assets that do not serve a critical function, or assets that do not have a predictable failure mode.
Condition-based maintenance is similar to predictive maintenance in that it involves continually monitoring specific conditions to determine when maintenance should be performed. Typically, however, condition-based maintenance is not just performed to prevent failure, but also to ensure optimum efficiency, which can not only improve productivity but extend the life of the asset as well. Because condition monitoring equipment and expertise can be expensive, initial costs can be quite high – prohibitive in some cases. In the long term, however, condition-based maintenance may be the most cost-effective strategy for ensuring optimal productivity and extended asset lifecycles. Condition-based maintenance is usually not a good choice for non-critical assets or older assets that may be difficult to retrofit with sensors.
When choosing a maintenance strategy, think about your goals: both long-term and short-term. Determine which of your assets are critical and which are not. Calculate the cost of downtime (per minute, per hour, etc.). Take into account whatever data may already be available for you to monitor. Determine the cost and viability of adding sensors to monitor things like temperature, vibration, electric currents, subsurface defects (ultrasonic sensing), or vacuum leaks (acoustic sensing). Estimate the costs of maintenance personnel in different scenarios. Estimate the difference in costs between each of the different strategies.
You may determine that a condition-based maintenance program would provide the greatest value, but you lack the resources to implement it right away. Can you deploy a simple predictive maintenance program in the meantime, while positioning yourself to make the leap to CBM in the future?
There is not going to be any one-size-fits-all “best” strategy, and not much drains a bank account faster than over-maintaining your equipment (yes, there is such a thing). Consider your circumstances and your goals, and choose wisely. It’s one of the most important business decisions you will make.
*B-Scada software provides data analysis, task automation, and real-time visualization for enterprises looking to implement a CBM program. Learn more at www.scada.com.