And taking equipment off-line for more extensive testing is not always an option. For an alternative, engineers at CCI Pope Ltd. in Australia developed ShafTest, a portable PC-based system that relies on ultrasonics to find cracks buried deep in the shaft. The device is designed to work on shafts in place on large machinery, as long as one end is exposed. The PC, a Dolch NotePAC Plus, is housed in an all-metal case, giving it NEMA-12 and IP52 ratings. It will also survive a 15-g shock. Software lets the computer detect flaws and collect and analyze data. For example, the software lets users plot cross sections at any depth in the shaft and highlight cracks. An IR LED on the ultrasonic transmitter/receiver attaches to the shaft, letting a camera record its position. Ultrasound readings are then correlated to that position. The detection system is distributed by Uni-Tech Engineering, Pelham, Ala. (unitechsales.com).
Testing shafts and axles with ultrasound
Finding small cracks in shafts or axles can be difficult.