OEMs often weld or press nuts onto relatively thin parts such as stampings and panels used in cars and truck. This lets manufacturers attach those parts to chassis, frames, and interiors using threaded fasteners. To ensure the proper nuts are welded in the correct positions, engineers at Norgren Automation Solutions (NAS), Littleton, Colo. (www.norgrenauto.com), have developed an eddy-current-based nut and thread sensor. The sensor induces eddy currents in part it is next to, then uses those currents to detects the presence of a nut, its threads, and the condition of those threads. The sensor usually mounts on a jig on an assembly or inspection line. The jig extends or rotates to insert the sensor into the nut.

Some companies, however, were using the sensor as a gaging or locating pin. This put considerably side stresses on the sensor. Other companies had jigs and arms that also put side stresses on the sensor. So NAS strengthened the sensor, letting it handle 150 lb of side loading and 75 lb of axial loading. This does not affect the device’s 25-msec response time or its 5 million cycle life. The device comes with power indicators, as well as short-circuit, overload, and reverse-polarity protection. The device is also modular, so parts can be individually replaced or upgraded as needed. Sensors are available for M4, M5, M6, M8, M10, and M12 sized nuts and threads.

Edited by Stephen J. Mraz

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