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The Kistler Group’s new piezoresistive melt pressure sensor opens up new possibilities for measurement technology. The Type 4004A sensor, with a front diameter of just 3mm, can be operated inside injection nozzles and small extruders, measuring both pressure and temperature in direct contact with the plastic melt.
Key highlights:
- 3mm diameter sensor fits inside injection nozzles and extruders
- Ideal for both hot runner systems in injection moulding, as well as in additive manufacturing
- Operating range of up to +350°C
- Can be installed in small nozzles with no critical changes to injection behaviour
- Pressure range of up to 2,500 bar for hot runner injection moulding, 1,000 bar for additive manufacturing
This miniature sensor is useful both for injection moulding and additive manufacturing. Due to its small size, it can be installed inside small nozzles without critically changing the injection characteristics. It has a working temperature range of up to +350°C, which means it’s useful for a wide range of materials and processes to deliver precise measurements of pressure and temperature in injection nozzles and extruders.
The Type 4004A piezoresistive melt pressure sensor
There are different parameters for the different processes: for the hot runner in injection moulding, it delivers high accuracy measurements up to 2,500 bar of pressure, while for additive manufacturing the pressure goes up to 1,000 bar. “The measured melt pressure can be used to control the plant in order to optimise the flow behaviour of the plastic melt,” says Dr. Robert Vaculik, Head of BU Plastics at Kistler. “If the process parameters remain constant but there are changes in the pressure signal, that would suggest possible anomalies – deposits in small nozzles, for example, wear in the mechanics or melt backflow. Process monitoring with this degree of accuracy was never possible until now.”
Kistler’s Transducer Electronic Data Sheet (TEDS) allows easy access to the Type 4004A’s internal key parameters. The sensor features a diaphragm of hardened steel and is rated to IP65 degree of protection. It can be used for applications involving fibre-reinforced plastics and is also safe to use in medical technology and food packaging sectors, as no oil or mercury is used for the transmission of signals.
The temperature-compensated pressure signal can be accessed via the analogue output, or the sensor’s RS232 interface. This means it’s compatible with measuring equipment such as the ComoNeo process monitoring system by Kistler. “With this innovation, we’re offering our customers a digital measuring chain for hot runner and additive manufacturing applications – the key to smarter monitoring of the melt flow in hot runner systems as well as additive manufacturing systems,” says Dr. Vaculik.