Meusburger Cavity pressure measurement increases process efficiency
Meusburger now offers two types of sensors, for direct and indirect cavity pressure measurement, which are compatible with all piezoelectric pressure sensors as well as their components.
The motto “everything from one source” from Meusburger extends now not only to standard parts for temperature, mould closing force and end position control but also sensors for cavity pressure measurement. The sensors are compatible with all piezoelectric pressure sensors as well as their components currently available on the market. Two types are available from stock, each for direct and indirect measurement, and the corresponding mounting accessories and connection cables.
Cavity pressure is an important parameter in process monitoring during plastic injection moulding, where pressure sensors are indispensable for comprehensive mould monitoring. The use of high-quality piezoelectric sensors thus allow for optimal process quality and also sustainably increases the quality of the part.
Functional principle and different applications
Cavity pressure sensors make it possible to convert the pressure in the cavity to a measurable charge, using the piezoelectric effect. The sensors have high-precision quartz crystals (SiO2 or α-quartz) that release a charge under the influence of pressure or force. This charge, which is then amplified by a charge amplifier, provides precise information about the pressure applied to the sensor to enable the monitoring of the exact cavity pressure during the injection moulding process. The ideal installation position in the mould depends on the application. For general monitoring and process optimisation, the sensor is placed as close as possible to the sprue or on a thicker section of the moulded part. Other typical applications are strength monitoring and the monitoring or controlling of viscosity, compression and shrinkage capabilities.
Direct and indirect sensors
Two types are available, depending on the application: direct and indirect sensors, which serve for direct or indirect pressure measurement.
The E 6740 cavity pressure sensor for direct measurement is inserted directly in the cavity to enable the cavity pressure to be measured directly in the respective area. When pressure is applied, the sensor delivers an electrical charge within the pC unit (Picocoulomb), which is then converted into a change of pressure (bar) through the specified sensor sensitivity (pC/bar).
The E 6750, on the other hand, is for indirect measurement, which is carried out by a force sensor that is located outside the cavity and is indirectly actuated by a force. Unlike the case of the direct sensors, the cavity pressure here is transmitted to the sensor as a force through an ejector pin. Response to this force, the sensor emits an electrical charge, which is then converted into a change of force (N) through the specified sensor sensitivity (pC/N). This change of force combined with the surface of the ejector is used to calculate the pressure change.