There are two types of laser additive manufacturing (LAM) equipment: powder beds and powder feeders: 1) laser fusion deposition, which is characterized by simultaneous powder feeding, and 2) selective laser melting, which is characterized by powder bed spreading. According to the classification definition of ASTM "ASTMF42 - Additive Manufacturing", SLA is classified as an optical polymerization process; SLS and SLM are classified as powder bed processes; and LENS is classified as a directed energy deposition process. These processes utilize different types of lasers and material deposition methods to achieve layer-by-layer manufacturing. The following highlights an overview of control valve flow monitoring in these two typical LAM technologies.
Currently, the most representative laser-based additive manufacturing processes include stereolithography (SLA), laser-selective sintering (SLS), laser-selective melting (SLM), and laser cladding (LENS). In particular, the mainstream technologies for additive manufacturing in industrial applications all use laser as the energy source to melt or bond the powder into shape, such as SLM, SLS, LSF and other technologies. During the process of powder melting, the laser can react with oxygen, nitrogen and other gases, resulting in substandard quality of molded parts. In order to prevent oxidation during the powder melting process, the processing area of general additive manufacturing laser forming equipment is protected by inert gas or vacuum environment.
In the existing technology, the atmosphere control is usually carried out first through the inlet and exhaust valves and hand-controlled flow meters to adjust the amount of inert gas entering each part of the equipment, and through the oxygen sensor to detect the oxygen content of the molding area, when the oxygen content is low, close the high-flow inert gas entry valve and open the low-flow inert gas entry valve, so as to maintain the atmosphere required for the entire molding process. The whole molding process is always fed with small flow rate gas, so that the oxygen content continues to decrease after reaching the requirement, thus causing unnecessary waste; secondly, if the oxygen content rises due to sudden accidents during the molding process, it will lead to switching back and forth between large flow rate gas and small flow rate gas, making the control procedure troublesome and the equipment stability poor;
This requires fluid control valves formed by monitoring additive manufacturing, which have properties that contribute to thermal management Handling flowing fluids at high pressures may require the use of control devices to achieve energy loss or high pressure drop. However, the extreme conditions of the fluid flowing through such control devices may cause corrosion of the control device due to cavitation (which can refer to the high rate of implosion of the fluid to the control device components). Corrosion of the control equipment may reduce the effectiveness of the control equipment to achieve the desired energy loss or high pressure drop ability. In addition to corrosion problems, the high pressure and high velocity flow of fluid may cause the flow characteristics within the valve to become unpredictable and unstable. To monitor the flow of fluids IST recommends the use of the Swiss IST Silicon Flow Sensor Thermal Mass Flow Sensor - SFS01.
The Swiss IST Silicon Flow Sensor Thermal Mass Flow Sensor-SFS01 is a silicon based calorimetric flow sensor with ultra fast response time for medical and industrial flow applications in the low flow and general temperature range.
