Autofrettage in pressure sensors ensures zero-point stability

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 technique is applied, to experience maximum stability, specifically of the zero point, in later operation. Assuming a suitable design 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 leading to zero-point shift or similar effects.
In autofrettage, certain local regions 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 put through and how often, must be determined individually for each sensor design through an elaborate FEM simulation and extensive test series.
Caution ? no experiments of your! However, Savagery should not be concluded that every sensor will automatically benefit from subjecting it to autofrettage. Master can only be utilized for ductile materials, but for no reason 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 additionally result in dangerous preliminary damage and subsequently possibly in accidents caused by fatigue and bursting of the sensor. In this way, a noticable difference in instrumentation will only be achieved, if, by hit or miss.

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