Frequency Domain Measurements of Melt Pool Recoil Force Using Modal Analysis
Recoil pressure is a critical factor affecting the melt pool dynamics during Laser Powder Bed Fusion (LPBF) processes. Recoil pressure depresses the melt pool, providing layer-to-layer fusion without introducing porosity. If the recoil pressure is too low, the process operates in a conduction mode where layers will not properly fuse, while excessive recoil pressure leads to a keyhole mode, which results in gas porosity. Direct recoil pressure measurements are challenging because it is localized over an area proportionate to the laser spot size producing a force in the mN range. This paper reports a vibration-based approach to quantify the recoil force exerted on a part in a commercial LPBF machine. The measured recoil force is consistent with estimates from high speed synchrotron imaging of entrained particles, and the results show that the recoil force scales with applied laser power and is inversely related to the laser scan speed. These results facilitate further studies of melt pool dynamics and have the potential to aid process development for new materials.
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Due to technical limitations, full-text HTML conversion of this manuscript could not be completed. However, the manuscript can be downloaded and accessed as a PDF.
Posted 17 Dec, 2020
On 04 Jan, 2021
On 15 Dec, 2020
On 15 Dec, 2020
On 10 Dec, 2020
Frequency Domain Measurements of Melt Pool Recoil Force Using Modal Analysis
Posted 17 Dec, 2020
On 04 Jan, 2021
On 15 Dec, 2020
On 15 Dec, 2020
On 10 Dec, 2020
Recoil pressure is a critical factor affecting the melt pool dynamics during Laser Powder Bed Fusion (LPBF) processes. Recoil pressure depresses the melt pool, providing layer-to-layer fusion without introducing porosity. If the recoil pressure is too low, the process operates in a conduction mode where layers will not properly fuse, while excessive recoil pressure leads to a keyhole mode, which results in gas porosity. Direct recoil pressure measurements are challenging because it is localized over an area proportionate to the laser spot size producing a force in the mN range. This paper reports a vibration-based approach to quantify the recoil force exerted on a part in a commercial LPBF machine. The measured recoil force is consistent with estimates from high speed synchrotron imaging of entrained particles, and the results show that the recoil force scales with applied laser power and is inversely related to the laser scan speed. These results facilitate further studies of melt pool dynamics and have the potential to aid process development for new materials.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
Due to technical limitations, full-text HTML conversion of this manuscript could not be completed. However, the manuscript can be downloaded and accessed as a PDF.