Sometimes it does not make sense to perform preventive maintenance (PM) from both a cost and time perspective. For instance, changing light bulbs every year is probably not a good use of time and parts. Receiving work requests for burnt bulbs might be a better alternative. In cases like this, preventive maintenance costs you more money than it saves. Also, it doesn’t have a high impact on the utility of the facility.
In other cases, preventive maintenance is necessary to avoid millions of dollars in unscheduled downtime. For instance, a piece of vital machinery in a manufacturing plant that produces thousands of dollars of product every hour needs a PM schedule. Taking a reactive maintenance approach here is not an option.
These are two examples of when you should not and should perform preventive maintenance. However, there are instances when the line is not as clear. Below, I’ll expand on these examples and offer a “gray line” case in an effort to help you decide where and where not to implement preventive maintenance.
The preventive maintenance model
There are three critical factors in preventative maintenance that you have to consider that I’ll list below in the form of questions. Your answers to these questions will help you understand whether you need a PM schedule in place.
- How bad is the worst case scenario?
- What is the likelihood of a breakdown?
- How much will it cost?
To help you answer these questions, let’s look at three examples.
Example 1: PM is not needed
Case: Replace light bulbs in the women’s bathroom every year.
The worst case scenario is that a bulb burns out. The bathroom has multiple lights, so worst case, not so bad. The likelihood of a bulb going out at some point is pretty high and the cost to do a PM on these lights every year is quite high given the relative impact it has. With that said, do you think it makes sense to do a PM on bathroom lights? Probably not. Let’s just wait until a bulb burns out and get a work request to replace it.
Example 2 : PM is needed
Case: Lube chains for critical equipment every seven days.
If there is a breakdown on a critical piece of equipment, that could stop production. This could mean a loss of thousands, maybe millions, of dollars. Also, the likelihood of a breakdown is probably very high because the equipment is constantly running. It’s probably a good idea to do a PM in this case.
Example 3: PM is questionable
Case: Change HVAC filter every six months.
The worst case is that our HVAC machine goes down. The likelihood of this is questionable. HVAC machines will still run with a clogged filter, but efficiency is reduced, causing increased costs. Do we PM this HVAC machine? Probably. But we have a few different levers to turn.
How often should we PM? Should we do it every four months, six months, or eight months? This is something that’s a bit controversial and needs to be looked at from a cost perspective. At the end of the day, PMs can be expensive if you are over PMing something. But they can help prevent critical failures. So we need to make sure we are PMing the right thing at the right frequency.
For instance, Scott Isackson, a maintenance manager and building advisor, has seen a lack of filter replacement damage motors that cost roughly 13 years of annual PM in an apartment complex for a single unit.
“Another example of when a PM is questionable is flushing and replacing the anode rod that can extend the life of a water tank,” says Isackson. “The process can be disruptive and requires the time of a plumber or someone of a higher skill level. The relatively low cost of a water heater makes it much better to replace at the end of it’s life. However, there can be some PM items performed such as hose replacements but it is dependent on the location of the water heater and the layout of the community.”
Use technology to optimize preventive maintenance
At the end of the day, we really want to move from reactive to predictive maintenance. As a maintenance manager, I want to know when the efficiency of a piece of equipment gets to a point where it makes financial sense to replace a specific part and create a work order. We can do this with new technology today like digitizing our maintenance with a CMMS.
Within the CMMS we can log meter readings. For instance, a factory maintenance manager can have machine operators periodically log the amount of cycles an injection molding machine runs through. Then they can analyze the data to see at which cycle counts reactive maintenance was needed. This can inform preventive maintenance schedules moving forward.
Maintenance managers can also add sensors to the assets. For instance, a vibrational sensor can be added to a machine to alert the manager when the machine’s vibrations reach a yellow or red line. This can then trigger a work order.
Technology like this can help you optimize your preventive maintenance schedules and determine whether a location or assets requires such a schedule.