Ultrasonic bolt stress meter

The MAX from Sonatest is an electronic stress meter designed to measure the actual clamp load produced by tightening a bolt or thread fastener. It uses ultrasonic energy and is designed for applications where the clamping force requires monitoring over the service life of a bolt or where the measurement of applied torque alone cannot obtain the required accuracy. The unit measures the resulting fastener elongation from 2.5mm to 6,000mm. The measurement is achieved by determining the change in the transit time of an ultrasonic shock wave along the length of the fastener as the fastener is tightened. The unit measures 19.7cm x 12.7cm x 27.9cm and weighs about 3kg. The screen and keypad have sealed membranes and the unit operates in ambient temperatures ranging from 0OC to 40OC. Automatic compensation for the temperature of the fastener is included. The meter automatically carries out verification of the fastener material calibration constants. It can also record and transmit data via an RS232 output port. A selectable tone burst pulser system allows a range of transducers to be used and low noise and automatic gain features allow signal detection and measurement to be carried out in difficult applications, says Sonatest. An automatic digital signal analysis system monitors the measurement processes and warns of potential problems.