A sensor is a sensing element (or Transducer) which qualitatively or quantitatively determines certain physical properties (temperature, pressure, length, speed, acceleration...) of the surroundings and turns them into electrical signals to elaborate them further. In measuring engineering, the term transducer is used according to DIN 1319-1 which is defined as a part of the measuring equipment immediately reacting to a measuring value. For this reason, the transducer and the sensor accordingly are the first measuring chain element.
In foundry, sensors have an increasingly important role in automated casting processes as signal transdurcers (especially for continuous mold casting and die casting). Determined values or states are electrically-electronically amplified, elaborated in the relevant control and further steps are initiated. For a couple of years, the subsequent signal processing has been performed in the sensor. Such sensor contain microprocessors or a microsystem and dispose of what might be called “intelligence”.
The term cavity sensor system comprises all sensors which determine and elaborate precess-relevant parameeters during the casting process from the cavity, i.e. immediately from a permanent mold and especially from a die casting mold (Fig. 1).
New measures on the filling behavior of die casting molds by using real-time sensors showed that slight process changes can result in extensive filling behavior changes. Theses process changes partially result from mold or melt temperature oscillations, on the other hand, the mold ventilation behavior is authoritative and/or totally new conditions can arise during the mold filling due to deviations from the casting speed and the filling amount. For complying with quality requirements it is necessary to obtain as many direct information as possible from the die casting mold during the casting process by using cavity sensors.
With die casting, today the following cavity sensors are used:
In addition to cavity sensors, several other measuring systems can be used for process data collection during die casting (see die casting process data collection) which can also contain sensors (Digital position measuring system, column bending measuring...)