Smart Bearings are in Control--But Full Potential Remains Untapped

To be clear, “smart” bearings—i.e., bearings and sensors integrated into a component to monitor bearing performance—are not new. They’ve been around for decades, dating back to military applications circa World War II. Since then, they have played a vital role, according to the Bearing Specialists Association (BSA), in the automotive, motion control, robotic control, paper and printing, web processing, wood processing, chemical, textile, agricultural and food processing industries. (Ed.’s Note: Please see accompanying BSA sidebar on smart bearings.)

Victoria Wikstr?m, manager of SKF’s industry applications segment group, provides some additional historical perspective.

“(Smart bearings were developed) for applications where personal damage and safety are key, and the consequences of a bearing failure can lead to serious injury and even fatality, as opposed to ‘merely’ fi nancial issues. Therefore, bearings in jet engines were fi rst to be monitored by sensors (in fl ight), and by inspections and oil analyses on the ground. The automotive industry’s adaptation of antilock brake systems (ABS) is probably the fi rst large-volume sensorized bearings (position sensoring). Railway locomotives and cars have been using temperature warning sensors for some 20 years, even if these were not mounted as an integral part of the bearing but as an add-on through the housing.

“For industrial applications, use of sensorized bearings has not been as widely adopted as the opportunities and available benefi ts that are out there. But with higher demands on uptime and reducing maintenance costs, it is defi nitely increasing—load sensing (using strain gages) for paper machines, vibrationand temperature-condition monitoring for many industries, oil quality sensors for gearboxes. Today, for car applications, SKF has working prototypes of load sensing via sensor technology integrated into the wheel bearings.”

Darin Davenport, product business manager for Dodge Roller Bearings, adds that in addition to the military applications, “Sensor technology was also likely improved through R&D dedicated to aerospace. We don’t have proof of this though. Dodge only started offering smart products in 1995, when we leveraged Rockwell (Automation’s) experience.” He adds, “Sensor and monitoring capabilities are the primary value added features, but the bearing housings are modifi ed to provide accurate sensor reading and proper sensor mounting.”

Given that bearings are often one of the most important components in a machine, system, etc.—and are often one of the fi rst to fail—having a reasonable expectation of their longevity is essential to maintaining peak performance cost. Smart bearings do just that in sensing vibration, temperature, speed, load and debris levels, to name just a few. Taken a step farther, they also are commonly used in industrial applications, in that the sensed data is extrapolated into condition monitoring systems for the monitoring of the aforementioned vibration and temperature issues. (Ed.’s Note: For more on condition monitoring, please refer to our feature story on page 20.)

According to the BSA, smart bearings have long played a big role in the automotive industry—in hub units, for example. That anti-lock braking system and traction control in your automobile are made possible by smart bearings.