SPC4^TM Load Indicating Fastener Technical

How Does it work?

A fastener is modified by machining a small hole into the head. Minimal modifications to the bolt assure basic bolt design integrity. A gage pin is inserted into the hole and secured at the bottom. A datum disk is fitted on the top of the bolt head and forms a flat surface with the top of the gage pin when the bolt is unloaded. When the bolt is tightened, it elongates and the gauge pin is drawn into the bolt away from the datum disk surface. A portable electronic displacement transducer measures the distance between the datum disk surface and the tip of the gage pin. The elongation of the bolt is then correlated to joint clamp load via an electronic hand held monitor.