Maintenance triggers are how you know there's work to be done. They're like the trigger in a starting pistol: once they're pulled, it's time to get moving. But how do you know which ones are right for your facility?
Not all maintenance triggers are created equal. Generally, we separate them into five categories according to best use and benefits.
Breakdown maintenance triggers
Here you're waiting until something stops working before you fix or replace it. Although on the surface this looks like the run-to-failure model an effective CMMS-back preventive maintenance program is designed to avoid, there's more to it. In some cases, it's best to let something run until it breaks.
Breakdown triggers work for anything:
with low criticality
whose failure is immediately noticeable
and that can be repaired or replaced quickly
with inventory that is cheap to carry
Take, for example, the batteries in a wireless keyboard. When's the best time to replace them? Right after they stop working. That way you're getting every last drop of power you paid for. And as long as you always keep fresh ones on hand, downtime is minimal. But not all batteries can be on a breakdown maintenance trigger. The ones in smoke detectors should be replaced on a set schedule. Remember, breakdown triggers only work for things with immediately noticeable failures, and you won't notice dead batteries in a detector until it's too late.
Time maintenance triggers
Time triggers are for tasks that need to get done regardless of how much you've used an asset. Come November it's time to switch to winter tires and fluids even on vehicles that have mostly sat idle. Other typical seasonal time triggers include checking on the air conditioning units before summer and the heaters before winter. The big advantage of time-based triggers is how far ahead you can plan, which gives you plenty of time to make sure you have the right parts, materials, and technicians when you need them.
You have to be a bit careful with using time-based triggers, though, because they can lead to both under and over maintenance, risking expensive repairs and downtime or wasting precious time and resources. Going back to the fleet example, it doesn't make sense to rotate the tires on every vehicle every six months when some are being driven hundreds of miles a day while others spend most of their time parked. In this situation, you're better off with usage triggers.
Usage maintenance triggers
Just like the name suggests, these triggers are based on how much something gets used. Unlike time triggers, where you measure the time between maintenance tasks, here you have to pick a specific unit of measurement for each asset. So, for example, you might replace a belt after so many hours of operation but a pump might be scheduled for maintenance after a specific number of cycles. Tires would be after so many miles. It's important to define usage carefully. You might be checking or replacing parts in a plane's engine based on the number of hours in the air, but usage triggers for the landing gear should be according to a specific number of takeoffs and landings, regardless of overall flight time.
Once you've decided what type of usage to measure, you need to establish the right amount between maintenance tasks. For the airplane engine, you're using hours in the air, so you need to decide how many hours. For the landing gear, you need to find the right number of takeoffs and landings. For highly regulated industries, deciding is easy. You follow government regulations. In unregulated industries, you can look at current best practices and manufacturers' recommendations. A great way to decide, and it really helps to have a user-friendly, feature-packed CMMS backing your maintenance department when you're doing this, is to look at an asset's work order history. If you know the pumps break roughly every 20,000 cycles, you can set your trigger for 19,000. A good CMMS software with autogenerated reports makes working with asset historical work order data a breeze. Without one, you have to track down and shuffle piles of paper or work out complex formulas for spreadsheets.
Event maintenance triggers
You can think of these as "if A then B" triggers. They're only done after specific events.
Let's say your facility just got a new roof, and the expectation is it'll last about 20 years. You can set up time-based triggers, and go up to check for problems once a year. But you're going to need some event triggers, too. You might want to go up to check for pooling after particularly strong summer storms. In the winter, you might need to send someone up to clear the roof after you get more than a foot or so of snow. The key point is that until it rains or snows, you don't do anything.
Event maintenance also covers what to do after an emergency. After a fire in the paint booth, you have a list of things that need to be checked. For example, any electrical wiring near the booth. If a tornado knocked out power in the area for a day, event maintenance triggers could automatically generate work orders for resetting the electrical system and getting assets back up and running. In a lot of these cases, third-party vendors are required because, for example, most maintenance department technicians can reset fire suppression systems. Here again, a good CMMS software is going to make your life a lot easier. From inside the CMMS, data-rich work orders are sent directly to vendors, with all the information they need to close out efficiently, including:
Customizable, step-by-step instructions
Associated parts and materials lists
Digital versions of O&M manuals
Complete asset work order history
A good CMMS will even have interactive floor plans.
Condition maintenance triggers
These triggers can be as low-tech as having a technician walk around assets to as high-tech as installing and monitoring sensitive vibration sensors. The basic idea is the same: anything out of the ordinary triggers maintenance. Your tech might notice a small puddle of oil under an asset. Your vibration sensor might detect a slight increase in movement. In both cases, you're going to investigate.
Condition maintenance triggers can be tricky. If you're asking a technician to walk through the facility looking for problems, they need to know what the assets look and sound like when they're running smoothly. Does the press always make that sound at the end of a cycle? Should that red light over the gear hobbing machine be on like that? A less-experienced tech might not know. Going the high-tech route, sensors have steep upfront costs, and interpreting the data requires additional training.
Choosing the right trigger for you
Efficient Plant has a great two-part (one , two) series on how facility managers choose and incorporate maintenance triggers. According to their panel of experts, the best choice is a combination of triggers that you actively fine-tune. It's also important to consider not only your assets but also your technicians.
"I think any of these methods can be very good, depending on the individual that uses them. PdM tools, in my opinion, are the best trigger available, provided they are in the hands of a trained person with the desire to learn and continue to improve their skills. Daily walks are also great if done by the right personnel."
Another key insight: How you set triggers changes over time, as you learn more about your assets.
"OEM 'recommendations' are just that -- and should be used with the backdrop of experience your company has with similar machines... I find OEM recommendations are very helpful with our new equipment, with which our experience is very limited."
"We basically begin with OEM recommendations and add to them as we learn more about the equipment. I believe that, over time, knowledge is gained that must be implemented into the scheduling. Each user has different issues with the equipment and the OEM specs are just a jumping-off point. How critical [certain] equipment is to your operation also comes into play."
The series is definitely worth your time. It's a quick read with lots of good information.
Implementing maintenance triggers is much easier with a user-friendly, feature-packed CMMS software. If the software you have now is underperforming or you're still trapped under a paper-and-pen or spreadsheet system, now's the time to start looking to upgrade to computerized maintenance management software. When talking with CMMS providers, make sure to ask them about their preventive maintenance module, what information can be added to work orders, and how easily third-party vendors can be managed through the software.