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In-situ powder bed surface topography for laser-based metal additive manufacturing process monitoring

Xiong, Yubo (2021) In-situ powder bed surface topography for laser-based metal additive manufacturing process monitoring. Master's Thesis, University of Pittsburgh. (Unpublished)

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Despite the rapid evolution of laser powder bed fusion (LPBF) based additive manufacturing (AM), the current LPBF systems lack the capabilities of monitoring the powder bed status such as surface topography, which could indicate the printed layer roughness and defects as well as the powder spreading uniformness. Therefore, an in-situ powder bed surface metrology method is desired to ensure built part fidelity and enhance process efficiency. In this work, we present an in-situ powder bed surface monitoring and measurement method using fringe projection profilometry (FPP). The FPP method uses a multi-phase shifting approach to obtain height profile of each layer during the LPBF process by projecting a sequence of sinusoidal varying intensity fringe patterns onto the powder bed and evaluating the fringe distortions. Measurement calibration is conducted specifically for applying FPP to LPBF process. In-situ sensor data analytics is performed with in-house codes that feature improved algorithms to estimate height profile. Experimental results with a commercial LPBF AM machine (EOS M290 DMLS) demonstrate that the developed in-situ FPP is capable of measuring the three-dimensional (3D) profile of each newly printed part layer as well as monitoring the powder bed characteristics such as surface roughness, actual powder layer thickness, and powder bed anomalies. Sample with a step surface are printed and the accompanied FPP sensor data is analyzed and validated by ex-situ Coordinate Measuring Machine (CMM). Height measurement uncertainties are explored quantitatively in this thesis.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Xiong, YuboYux38@pitt.eduyux38
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairZhao,
Committee MemberTo,
Committee MemberJacobs,
Date: 13 June 2021
Date Type: Publication
Defense Date: 7 December 2020
Approval Date: 13 June 2021
Submission Date: 22 January 2021
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 88
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Mechanical Engineering
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: Additive Manufacturing; In-situ Metrology; Fringe Projection Profilometry
Date Deposited: 13 Jun 2021 18:53
Last Modified: 13 Jun 2021 18:53


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