Complementary Use of Optical Metrology and X-Ray Computed Tomography for Surface Finish and Defect Detection in Laser Powder Bed Fusion Additive Manufacturing

Published

July 25, 2018

Author(s)

Jason C. Fox, Felix H. Kim, Zachary C. Reese, Christopher Evans

Abstract

The development of additive manufacturing (AM) has allowed for production of high-value and complex parts that reduce time-to-market and cost to manufacture. A key benefit to the AM process is the capability to create lattice structures and highly complex, topology optimized parts that reduce weight. Despite this advantage, however, a limiting factor affecting widespread adoption of AM is the as-built surface topography of finished parts. Traditional surface metrology equipment often requires line of sight or adequate clearance to contact the surface with a stylus, which can be difficult to achieve given the highly complex AM geometries. The purpose of this research is to investigate the complimentary use of optical metrology and x-ray computed tomography (XCT) for inspection of parts built through laser powder bed fusion (L-PBF) AM with the primary focus being the benefit that the volumetric XCT data can provide when aligned with the data from conventional surface metrology equipment. Samples made from 17-4 stainless steel (17-4SS) and nickel super alloy 625 (IN625) are measured using a laser confocal (LC) microscope and XCT system. Defects, which include reentrant features on the surface and near surface pores, are identified and located from the XCT data. The data from the XCT and laser confocal (LC) systems is then aligned using an iterative closest point (ICP) algorithm. This alignment allows for identification of locations in the LC data close to near surface defects and provides more context on numerical analysis.

Proceedings Title

Proceedings of the 2018 ASPE and euspen Summer Topical Meeting - Advancing Precision in Additive
Manufacturing

Volume

69

Conference Dates

July 22-25, 2018

Conference Location

Berkeley, CA

Conference Title

2018 ASPE and euspen Summer Topical Meeting - Advancing Precision in Additive Manufacturing

Pub Type

Conferences

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Keywords

additive manufacturing, surface texture, x-ray computed tomography

Citation

Fox, J. , Kim, F. , Reese, Z. and Evans, C. (2018), Complementary Use of Optical Metrology and X-Ray Computed Tomography for Surface Finish and Defect Detection in Laser Powder Bed Fusion Additive Manufacturing, Proceedings of the 2018 ASPE and euspen Summer Topical Meeting - Advancing Precision in Additive Manufacturing, Berkeley, CA, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=926223 (Accessed October 27, 2025)