Abstract

Recoil pressure is a critical factor affecting the melt pool dynamics during Laser Powder Bed Fusion (LPBF) processes. Recoil pressure depresses the melt pool. When the recoil pressure is low, thermal conduction and capillary forces may be inadequate to provide proper fusion between layers. However, excessive recoil pressure can produce a keyhole inside the melt pool, which is associated with 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.

Department(s)

Mechanical and Aerospace Engineering

Comments

U.S. Department of Energy, Grant DE-NA0002839

International Standard Serial Number (ISSN)

2045-2322

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2021 The Authors, All rights reserved.

Publication Date

01 Dec 2021

PubMed ID

34040081

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