New Additive Manufacturing classification system to feature at TCT360 Conference
Ehsan Rahimi, a Senior Researcher at the Materials Processing Institute, will be at the TCT360 Additive Manufacturing Conference in June at the NEC, Birmingham, UK, where he will be presenting evaluating the impact of each parameter on flowability to optimise powder production for the laser powder bed fusion process. This supports the proposal that the Additive Manufacturing community agrees on a definition for classification groups.
A Versatile Approach to Interpret and Classify Powder Flowability in Laser Powder Bed Fusion Process and Powder Reuse
Date: Thursday, 08 June 2023
Time:12:00 - 12:30
Venue: TCT360 Additive Manufacturing Conference, NEC, Birmingham, UK.
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Powder flowability is a critical and complicated physical characteristic in the powder bed fusion process, which is influenced by particle size distribution, morphology, density, surface properties, electrostatic charge, and moisture. Evaluating the impact of each parameter on flowability to optimise powder production for the laser powder bed fusion process is of high importance. In the absence of a global standard for quantifying the distribution of morphological classifications, it is proposed that the Additive Manufacturing community agrees on a versatile definition for classification groups including circular and elongated particles, satellites, and agglomerates. The definitions are based on single or multiple standard shape descriptors for each classification group.
In a recent publication at WorldPM2022 congress, the Materials Processing Institute and Liberty Powder Metals Ltd presented some empirical definitions for morphological classifications. This approach was followed by proposing a new weighted index to interpret the impact of morphological distribution on flowability parameters. This work was conducted on 316L stainless steel. The Institute aims to continue this approach on other common alloys used in the powder bed fusion process including, IN718. In each set of experiments, an empirical equation for every alloy is introduced, and consequently, a universal parameter will be developed to interpret powder performance in the re-coating process.
For verification, the developed index was plotted against the flowability parameters, and a cut-off value below which a sample indicates an accepted flowability in the re-coating process was determined. The samples with an index above the cut-off value show that their flowability is driven by morphological distribution. For further verification, a certain number of tensile bars for each alloy were made, and the samples were tested against ASTM standards to validate the defined cut-off value.
The approach of generating a versatile parameter to correlate the morphological distribution and flowability can also be applied to the waste powder from the L-PBF runs, and hence, the powder capability for reuse can be quantified and assessed. The powder manufacturers can use this method to rank their products and evaluate their performance in the laser powder bed fusion process.
Ehsan Rahimi, Senior Researcher, Materials Processing Institute
Ehsan Rahimi is a Senior Researcher in the Advanced Materials Group at the Materials Processing Institute where he leads innovative projects in powder characterisation and additive manufacturing. He also conducts research in chemical analysis, materials characterisation at room and elevated temperatures utilising state-of-the-art equipment such as X-ray fluorescence (XRF), optical emission spectroscopy (OES), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal analysis (thermogravimetric analysis, TGA, dynamic scanning calorimetry, DSC) and high-temperature viscosity.
TCT360 brings together market-leading technology suppliers, service companies and research organisations at the largest Additive Manufacturing and 3D Printing conference in the UK. It provides an opportunity to learn from world-class conference speakers and find out about the latest applications, future trends and ways to reduce production costs and emissions.
18 April 2023