Electronics & Connectivity - September 5, 2012 - 11

Many uses of bearing diagnostic data
Bearings are everywhere. They’re at the heart of any machine that rotates. On excavators or wheel loaders, roller bearings are usually somewhere in the shaft. Bearing diagnostics are great for detecting problems about the machines, not just the bearings themselves. Instead of performing maintenance on a fixed schedule, a company could better plan maintenance and perform it only when needed. Bearing monitoring sensors can send a signal saying: “there is a small damage here.” One type of bearing diagnostics measures machine condition and attempts to determine whether a system has problems and where they are. These diagnostics involve at least three types of measurements: bearing speed, temperature, and vibrations. Victoria VanCamp, Head of Business Intelligence and Engineering for SKF Industrial MarketStrategic Industries Off Highway, says that vibrations can come from within the bearing itself, if there’s damage or a crack in the material under the surface or in a gear tooth, or even in a differential gear far away from the bearing. Acoustic emission sensors detect high-frequency vibrations, and algorithms calculate where they came from. The technique is sensitive enough to locate the gear and even the specific gear tooth that caused a vibration. Another bearing diagnostic technology uses monitoring signals to control operation of the electric motor under evaluation. These sensors measure bearing speed, position, and rotation direction, and feed signals back to the motor through a control unit to improve efficiency. VanCamp says that these type of diagnostics provides “need-toknow” information about the shaft, but not so much from the bearings. They are commonly used in high-efficiency stationary industrial motors, in electric cars, railway traction motors, and on hybrid wheel loaders and electric loaders. “What’s more interesting is what’s coming,” said VanCamp. “It’s not yet common to use a bearing’s diagnostic history, but it is possible to download
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Bearing diagnostics comes in handy not just for the bearings themselves, but also for detecting problems about the equipment they inhabit. (SKF) data about its temperature, placement in the shaft as it moves back and forth, and vibrations over its entire life. Using smart algorithms, this data could be used to predict a reasonable maintenance interval based on the actual history of that specific machine. You no longer need to wait until there’s a failure to respond.” SKF manufactures its own bearings, specifies sensors, and processes the signals from those sensors. The company is moving in the direction of creating algorithms to evaluate the signals and predict the remaining life of a machine. “In the future, wireless technology will be more widely used with diagnostic data,” VanCamp said. “It’s possible now in the lab. The future is already here in experimental installations, measuring the same sensor parameters as with wired but sending signals to a central unit totally wirelessly.” “The main wireless business right now is from fleet owners and end users who retrofit their machinery with bearing monitors. Some prefer to maintain regularly instead of installing sensors,” she added. “That works, but they may spend a lot more money over the life of the product.” In 10 years, sensors will be all over machines, but not all of them will be on; depending on the machine options purchased, flexible monitoring options will be available. “End users will save money. They will make better use of their fleet by saving fuel [and] using their equipment more efficiently,” said VanCamp.
Debbie Sniderman
September 5, 2012

Electronics & Connectivity - September 5, 2012

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