Multi-faceted monitoring of powder flow rate variability in directed energy deposition

Freeman, Felicity; Thomas, Bethan; Chechik, Lova; Todd, Iain

doi:10.1016/j.addlet.2021.100024

Cited by 13 publications

(12 citation statements)

References 17 publications

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“…With regard to a process control to ensure the layer height in a LMD-w process, a coaxial OCT (optical coherence tomography) system was used in [158]. In [159], laser measurements were used for optical powder flow analysis as well as coaxial molten pool detection to identify powder feed irregularities in the LMD-p process. A special in-situ microscope for observing selective laser sintering was presented in [160].…”

Section: Measuring Methodsmentioning

confidence: 99%

The Additive-Subtractive Process Chain - a Review

Möhring¹,

Maucher²,

Becker³

et al. 2023

Journal of Machine Engineering

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In recent years, metal additive manufacturing developed intensively and became a relevant technology in industrial production of highly complex and function integrated parts. However, almost all additively manufactured parts must be post-processed in order to fulfil geometric tolerances, surface quality demands and the desired functional properties. Thus, additive manufacturing actually means the implementation of additive-subtractive process chains. Starting with the most relevant additive processes (powder-based PBF-LB, LMD-p and wire-based WAAM and LMD-w/WLAM), considering intermediate process steps (heat treatment and shot peening) and ending up with post-processing material removal processes (with defined and undefined cutting edges), this paper gives an overview of recent research findings with respect to a comprehensive scientific investigation of influences and interactions within the additive-subtractive process chain. This includes both the macroscopic geometric scale and the microscopic scale of the material structure. Finally, conclusions and future perspectives are derived and discussed.

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Section: Measuring Methodsmentioning

confidence: 99%

The Additive-Subtractive Process Chain - a Review

Möhring¹,

Maucher²,

Becker³

et al. 2023

Journal of Machine Engineering

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“…The powder used was gas atomised 316 L steel powder from Sandvik (referred to here as GA316), at a flow rate of 7.2 ± 1.3 g/min (Freeman et al, 2021). The powder had a nominal size range of 45-90 µm.…”

Section: Methodsmentioning

confidence: 99%

Calibrated Closed-Loop Control to Reduce the Effect of Geometry on Mechanical Behaviour in Directed Energy Deposition

et al. 2022

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“…The resultant 12bit images (500 x 500 px, where 1 px = 5.4 µm) were analysed in MATLAB R2021b (Mathworks Inc). For each image, all the pixels were summed to give an overall thermal intensity as previously reported 21,35 ; this is a sum of pixel digital levels, so is unitless. This was compared to both the maximum intensity in a single image and to the melt pool area, both showing strong correlation below a thermal intensity of 0.2x10 7 34 , below which, the laser power was ramping at the ends of each hatch.…”

Section: Manufacturing and Monitoringmentioning

confidence: 99%

Controlling grain structure in metallic additive manufacturing using a simple, inexpensive process control system

Chechik

Goodall

Christofidou

et al. 2023

Preprint

Self Cite

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Additive manufacturing (AM), commonly termed 3D printing, is a revolutionary manufacturing technology with great industrial relevance in the aerospace, medical and automotive sectors. Metallic AM allows creation of complex intricate parts and repair of large components; however, certification is currently a concern due to lack of process consistency. A simple, inexpensive process control system was developed and integrated, reducing variability in melt pool fluctuation and improving microstructural homogeneity of components. Remnant microstructural variation can be explained by the change in heat flow mechanism with geometry. The grain area variability was reduced by up to 94% at a fraction of the cost of a typical thermal camera, with control software written in-house and made publically available. This decreases the barrier to implementation for process feedback control, which can be implemented in many manufacturing processes, from polymer AM to injection moulding to inert-gas heat treatment.

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Multi-faceted monitoring of powder flow rate variability in directed energy deposition

Cited by 13 publications

References 17 publications

The Additive-Subtractive Process Chain - a Review

The Additive-Subtractive Process Chain - a Review

Calibrated Closed-Loop Control to Reduce the Effect of Geometry on Mechanical Behaviour in Directed Energy Deposition

Controlling grain structure in metallic additive manufacturing using a simple, inexpensive process control system

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