In the manufacturing operation of pressure sensors, autofrettage denotes the procedure of active ?overload? by subjecting the pressure sensor selectively once or many times to a pressure above the nominal pressure range. This process is applied, to experience maximum stability, specifically of the zero point, in later operation. Assuming a suitable design of the sensor, autofrettage enables many years of trouble-free operation of the sensors even at high load cycles reaching the specified overload range, without leading to zero-point shift or similar effects.
In autofrettage, certain local areas of the sensor, where during the selective overload the yield point of the sensor material is locally exceeded, become plasticised, producing a permanent change of the instrumentation characteristics. This selective effect on the structural conditions through autofrettage is an integral portion of the development of the sensor and of the associated manufacturing process. Which pressure the sensor is subjected to and how often, must be determined individually for every sensor design by means of an elaborate FEM simulation and extensive test series.
Caution ? no experiments of your! However, it should not be concluded that every sensor will automatically benefit from subjecting it to autofrettage. pressure gauge octa can only just be used for ductile materials, but under no circumstances for brittle ones. Conditioning should be scheduled and carried out very selectively sufficient reason for great care during the production stages. Ill-considered ?overpressurising? of pressure sensors by laymen who like experimenting can not only damage the sensor permanently, but additionally bring about dangerous preliminary damage and subsequently possibly in accidents due to fatigue and bursting of the sensor. In this manner, a noticable difference in instrumentation will only be achieved, if at all, by hit or miss.