Looking to source automation, power transmission and motion engineering equipment? www.drives-guide.com Drives& Controls Interactive Buyer’s Guide website Drives&Controls & BACK TO BASICS n SPONSORED BY Are you lubricating your motors properly? An estimated 51% of motor failures are a result of bearing problems. The most common issue is insufficient lubrication. ABB’s David Blissett explains where motor users are going wrong, and how to keep your motors well lubricated and running smoothly. Lubricating bearings is one of the most important jobs when it comes to motor care. Yet I’m increasingly seeing motors being sent back to us with bearing failures caused by insufficient lubrication, which suggests that too many users simply aren’t lubricating properly. Back in my day, plants would have what we’d call a “grease monkey”, who would go around once a month and lubricate every motor. As maintenance teams get stretched ever thinner, it seems that this job is in danger of being overlooked. Bearings that are approaching failure give off a distinctive rumble or high-pitched sound as the motor’s ball-bearings pass over the worn spot. In years gone by, an experienced engineer would stick a screwdriver on the motor frame and, just by listening to the vibrations, would be able to tell if the bearings were about to fail. In these times of leaner maintenance teams and remote monitoring, this is a skill that’s dying out. If a motor has regreasable bearings, then it should also have a lubrication plate or O&M manual. This shows how frequently you should lubricate the bearings in duty hours, depending on how and where the motor is operating. It also sets out how much grease to use, and of what grade. When regreasing, it’s important to follow these instructions closely. Just like the engine oil in your car, grease wears out over time. It’s therefore no good just pouring more in. You have to let the old grease out first. Overfilling will smother the bearings and cause them to overheat, so the top-up must be carefully measured out and performed with grease relief valves open. Using the wrong grade – one not specified on the lubrication plate – will invalidate the warranty and could damage the motor. Actual duty hours will vary from motor to motor, so the easiest way to ensure that you’re lubricating at appropriate intervals is to have an effective preventative maintenance program, or to use smart sensors to measure running hours and provide you with a reminder when it’s time for regreasing. Ideally you would have both. Sensors have the added bonus of being able to monitor vibrations and provide early warnings of bearing failures as well as other problems. A lot of motor users don’t realise that bearings are responsible for such a high proportion of motor failures. But remember, five minutes spent regreasing using 20 pence worth of grease, is much cheaper than letting the bearings fail and having to replace them, or spending thousands of pounds on a new motor. For more information, search for “ABB Motion Service”.
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