In-situ surface roughness evaluation of laser powder bed fusion surfaces using optical tomography

Abstract

Laser powder bed fusion (LPBF) is an additive manufacturing technique that enables significant design freedom and high-complexity part production. However, the process requires unconventional analysis methods for surface characterization due to process-induced variations. One possible technique is to use in-situ optical tomography (OT) technique for quality control of LPBF surfaces during fabrication. In-situ characterization approach would enable better first time yield and inspection possibility of inner channels without the need of destructive testing. In this study, samples with varied angles and process parameters are produced by LPBF. Camera images are collected during the production per every process layer using the optical-tomography system. These OT images are interpreted to obtain roughness estimates of sample overhanging surfaces. OT roughness outputs are analyzed and correlated with optical coherence scanning interferometry (CSI) measurements. The relationship between OT surface roughness estimates and optical measurements for different process parameters are presented. The possibility of using an in-situ surface analysis method for the characterization of LPBF surfaces is discussed.