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Improved Melt Pool Monitoring Systems for Direct energy Deposition Processes / Robert J. Sampson

DOI (Published version): 10.23889/Suthesis.52474

Abstract

Additive Manufacturing (AM) processes have previously benefited from the introduction of parameter monitoring systems, with melt pool monitoring majorly contributing to this field of research. Current melt pool monitoring systems are typically emissivity-based image processing techniques. Melt pool mo...

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Published: 2019
URI: https://cronfa.swan.ac.uk/Record/cronfa52474
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Abstract: Additive Manufacturing (AM) processes have previously benefited from the introduction of parameter monitoring systems, with melt pool monitoring majorly contributing to this field of research. Current melt pool monitoring systems are typically emissivity-based image processing techniques. Melt pool monitoring systems have successfully been used to grant advanced process understanding, develop control systems and improve deposition quality. By improving the optical acquisition techniques in melt pool monitoring systems, a more enhanced and clearer image of the melt pool has been created, which contains features that indicate the true edges. These new features have been used to compare the conventional emissivity-based image processing techniques with a newly developed image process-ing technique. Comparing both techniques with extracted frames has highlighted potential flaws in conventional image processing algorithms and improved the understanding of melt pool radiation me-chanics and dynamics throughout direct energy deposition processes. The newly developed algorithm provided more accurate melt pool width calculations when compared with the emissivity-based edge detection technique and has been used to study changes in melt pool width with varying laser power settings. The new algorithm was used for subsequent parametric studies to understand the relationship between powder mass flow rate, path velocity and melt pool width. It was discovered that the rela-tionship between these parameters and melt pool width was complex and further parametric studies using the optimised melt pool algorithm should be conducted. The new algorithm was successfully used to calculate melt pool widths for multiple materials without the need for emissivity values. Melt pool width calculations were performed on multiple materials after minor calibration procedures.
Item Description: A selection of third party content is redacted or is partially redacted from this thesis.
Keywords: Additive Manufacturing, Direct energy deposition, Melt pool monitoring, Near-infrared imaging, Melt pool, process monitoring
College: College of Engineering