As mentioned, the strain sensors mostly use strain gauge technology. BoltSafe sensors are specially designed to measure bolt load, but are also capable of measuring other types of load. Our sensors use magnetoelastic technology and therefore measure changes in the magnetic field. Because of this technology, BoltSafe sensors are more compact and less expensive than strain sensors. Knowing the bolt load in a bolted construction enhances safety, gives better control and makes joints more dependable.
When they are used for measuring bolt load, they are used as washers which are placed on the non-driven side of a bolted connection, preferably under a nut. Tightening the bolt results in minor deformations of the stainless steel washer. This gives a change in the electrical resistance, which the sensor measures. We use this data to determine the bolt load at any given moment, as well during assembly as over time. This is a different method than measuring the elongation of the bolt to determine the force that was applied to it, but results in the same knowledge: knowing the bolt load.