Autofrettage in pressure sensors ensures zero-point stability

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 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 resulting in zero-point shift or similar effects.
In autofrettage, certain local regions of the sensor, where through 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 influence on the structural conditions by means of 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, should be determined individually for each sensor design through an elaborate FEM simulation and extensive test series.
Buffoon ? no experiments of your! However, it must not be figured every sensor will automatically reap the benefits of subjecting it to autofrettage. Autofrettage can only be utilized for ductile materials, but for no reason for brittle ones. Conditioning must 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 will not only damage the sensor permanently, but additionally result in dangerous preliminary damage and subsequently possibly in accidents due to fatigue and bursting of the sensor. In this manner, an improvement in instrumentation is only going to be achieved, if, by hit or miss.

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