Topography of selectively laser melted surfaces: A comparison of different measurement methods

Abstract

Selective laser melting (SLM) of metals produces surface topographies that are challenging to measure. Multiple areal surface topography measurement technologies are available, which allow reconstruction of information rich, three-dimensional digital surface models. However, the capability of such technologies to capture intricate topographic details of SLM parts has not yet been investigated. This work explores the topography of a SLM Ti6Al4V part, as reconstructed from measurements by various optical and non-optical technologies. Discrepancies in the reconstruction of local topographic features are investigated through alignment and quantitative assessment of local differences. ISO 25178-2 areal texture parameters are computed as further comparison indicators.

Surface texture evaluation of additively manufactured metallic cellular scaffolds for acetabular implants using X-ray computed tomography

“…They also took surface determination and filament into consideration and found that Sa resulted from XCT before and after the filament change was 1.8% and 2.7% higher than that of focus variation. Thompson et al [25] illustrated a comparison study of using three optical systems and one XCT system to measure the internal surface texture of a direct metal laser sintering (DMLS) artefact and found that Sa and Sq generated by XCT measurement are similar to those of confocal microscopy and coherence scanning interferometry.…”

Similarity evaluation of topography measurement results by different optical metrology technologies for additive manufactured parts

“…However, such evaluation is based on cross-sectional lines which may not well represent the inherent differences among these systems. To address such issue, some researchers proposed to inspect the arithmetic mean height of the surface which takes all the surface data into consideration [13,14]. Although the entire surface data points are utilized, the surface roughness parameters are essentially aggregated features of the data, and the geometric distributions of data points may be neglected.…”

X-Ray Microcomputed Tomography in Additive Manufacturing: A Review of the Current Technology and Applications

“…81,82 It was shown previously that individual line profiles in CT images can be related to surface roughness, especially useful for complex parts such as struts in lattices. 83,84 Recent advances in image processing of high-quality mi-croCT scans have demonstrated that it is possible to measure surface topography of AM parts generally, 85 also for internal surfaces of complex parts. 49,72,86 The term topography is used since the resolution does not allow for roughness measurements near or below the resolution of the scan, and the method is therefore different from typical traditional surface roughness measurements.…”