In the manufacturing operation of pressure sensors, autofrettage denotes the process 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, in order to achieve maximum stability, in particular of the zero point, in later operation. Assuming Graceful of the sensor, autofrettage enables a long time of trouble-free operation of the sensors even at high load cycles reaching the specified overload range, without resulting in zero-point shift or similar effects.
In Charming , certain local areas of the sensor, in which during the selective overload the yield point of the sensor material is locally exceeded, become plasticised, resulting in a permanent change of the instrumentation characteristics. This selective influence on the structural conditions by means of autofrettage is an integral part of the development of the sensor and of the associated manufacturing process. Which pressure the sensor is subjected to and how often, should be determined individually for each sensor design through 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. Autofrettage can only be utilized for ductile materials, but under no circumstances for brittle ones. Conditioning must be scheduled and completed very selectively and with great care through the production stages. Ill-considered ?overpressurising? of pressure sensors by laymen who like experimenting will not only damage the sensor permanently, but also bring about dangerous preliminary damage and subsequently possibly in accidents caused by fatigue and bursting of the sensor. In this way, a noticable difference in instrumentation is only going to be achieved, if, by hit or miss.