Metal Additive Manufacturing Conference - MAMC 2023

Integration of mass flow and pressure sensors in the gas supply system with the goal to control gas distribution and evaluate gas consumption is already common. A newly introduced FGF sensor module combines thermal mass flow, gas density and pressure in a single flow channel. The FGF module can identify gas type and compensate mass flow measurement accordingly. If, for example, inert gas supply switches from Argon to inexpensive Nitrogen for a less sensitive procedure, the module automatically takes notice, tracks the change and mass flow measurement maintains ≤±3%f.s. accuracy. As an additional safety function, gas flow in both directions can be measured. During idle periods, any gas flow in the wrong direction can be evaluated as leakage indication. This multiparametric module is designed and manufactured in close cooperation by Truedyne Sensors AG and IST AG, with both companies being part of Endress+Hauser and dedicated to compact sensor solutions for process control.
Eval-Kits | TrueDyne Sensors AG
Laser optics is sensitive to condensation, while metal powder raw materials are hygroscopic in nature and require dry storage and processing environment. Multiple measuring points, where reliable humidity measurement can enable fast process control and thereby optimal use of resources for high quality products, have been identified. In the processing chamber, a well-positioned humidity sensor can ensure that any residual humidity is purged, and no condensation is present on sensitive optical components. Purging based on the signal from a RH/T sensor can therefore shorten start-up time and directly translate into lower cost of process gases.
As additive manufacturing processes get more complex and processing times longer, maintaining low humidity and stable temperature conditions becomes just as important as instituting them. IST AG newest generation of RH/T sensors integrate a ceramic microheater, which is applied to condition the capacitive humidity sensor. A quick reconditioning procedure, which takes only a couple of minutes, significantly improves long-term accuracy. Since requirements for process connections are as individual as clothes, IST AG can dress RH/T modules in custom shaped housings to fit assembly needs. Even more important is the possibility to fit calibration to monitored thresholds. As an example, a common low humidity calibration allows to evaluate dew point at -40°C with +/-4°C Td.
Humidity module for dew point monitoring, assembled | IST AG (ist-ag.com)
Last sensor innovation to be addressed is temperature measurement of the build-in plates holding the manufactured product. Much effort is invested into creating an even temperature distribution with the printing bed temperature being one of the tightly controlled process parameters. Multiple temperature sensors are usually incorporated and need to be evaluated as an array. Such a multipoint measurement can benefit from a build-in reliable master sensor, against which all other temperature sensors can be checked or even reset in a remotely controlled recalibration procedure. For this purpose, IST AG has designed a new temperature module. It combines a resistive Pt1000 element with capacitive Curie point detection to create a unique temperature sensor with an automatic precision check every time the selected Curie point temperature is crossed. The sensor tip fits into all standard probe dimensions between 3 and 6 mm. A small signal evaluation board, which can be positioned remotely at up to 1.5m distance has a digital (I2C) interface and transmits the measured temperature along with information on the last precision check performed.