Multiple Sensor Detection of Process Phenomena in Laser Powder Bed Fusion

Published

May 20, 2016

Author(s)

Brandon M. Lane, Eric P. Whitenton, Shawn P. Moylan

Abstract

Laser powder bed fusion (LPBF) is an additive manufacturing (AM) process in which a high power laser melts metal powder layers into complex, three-dimensional shapes. LPBF parts are known to exhibit relatively high residual stresses, anisotropic microstructure, and a variety of defects. To mitigate these issues, in-situ measurements of the melt-pool phenomena may illustrate relationships between part quality and process signatures. However, phenomena such as spatter, plume formation, laser modulation, and melt-pool oscillations may require data acquisition rates exceeding 10 kHz. This hinders use of relatively data-intensive, streaming imaging sensors in a real-time monitoring and feedback control system. Single-point sensors such as photodiodes provide the temporal bandwidth to capture process signatures, while providing little spatial information. This paper presents results from experiments conducted on a commercial LPBF machine which incorporated synchronized, in-situ acquisition of a thermal camera, high-speed visible camera, photodiode, and laser modulation signal during fabrication of a nickel alloy 625 AM part with an overhang geometry. Data from the thermal camera provides temperature information, visible camera provides observation of spatter, and photodiode signal provides high temporal bandwidth relative brightness stemming from the melt pool region. In addition, joint-time frequency analysis (JTFA) was performed on the photodiode signal. JTFA results indicate what digital filtering and signal processing is required to highlight particular signatures. Image fusion of the synchronized data obtained over multiple build layers allow visual comparison between the photodiode signal and relating phenomena observed in the imaging detectors.

Proceedings Title

Proceedings of the SPIE Defense, Security, and Sensing

Volume

9861

Conference Dates

April 18-21, 2016

Conference Location

Baltimore, MD

Conference Title

Thermosense: Thermal Infrared Applications XXXVIII

Pub Type

Conferences

Download Paper

https://doi.org/10.1117/12.2224390

Keywords

Laser powder bed fusion, Additive manufacturing, thermography, photodetector

Citation

Lane, B. , Whitenton, E. and Moylan, S. (2016), Multiple Sensor Detection of Process Phenomena in Laser Powder Bed Fusion, Proceedings of the SPIE Defense, Security, and Sensing, Baltimore, MD, [online], https://doi.org/10.1117/12.2224390 (Accessed November 21, 2024)