X-ray computed tomography surface topography measurement: industrial case studies

Abstract

X-ray computed tomography (XCT) can be used for the measurement of surfaces and is particularly applicable to the measurement of internal or otherwise difficult-to-access surfaces. Also, recent research has shown that the lateral resolution achievable using XCT is approaching that achieved by contact and optical surface measurement technologies. While XCT surface measurement has been examined in a research environment during the past few years, application of the technology to industrial cases has been less well explored. Additionally, XCT surface measurements have, thus far, only been applied to relatively rough surfaces (i.e. where the arithmetical mean height of the scale limited surface, Sa > 1 μm). Results comparable to those acquired using established surface measurement technology have been acquired by measurement of these rough surfaces using XCT systems, but little investigation has been performed on measurement of smoother surfaces. Recently, industrial collaborators have expressed an interest in measuring smooth surfaces as part of the European 'AdvanCT' project. Here, we present an investigation into XCT measurement of relatively smooth surfaces (Sa < 1 μm), applied directly to a number of industrial cases (see figure 1a and 1b) and compared to another case study presented in previous work (see figure 1c). XCT data are acquired at the Danish Technological Institute and the University of Nottingham, and compared to coherence scanning interferometry (CSI) data for the same surfaces. Characterisation is performed using established and recently developed methods (ISO 25178-2 parameters and direct statistical topography comparison, respectively). The results presented show the ability (or lack thereof) of XCT to measure relatively smooth surface topographies, through comparison to optical measurements made using CSI, given its lower lateral resolution of. The case studies presented here are designed to provide further information about the capability of XCT systems for measuring surface topography, particularly in an industrial context and for smooth surfaces. We would like to acknowledge Novo Nordisk and 3TRPD for supplying case studies, and the Danish Technological Institute for providing XCT data. a) b) c) Figure 1. Example industrial parts to be measured during this case study: a) animal mask; b) insulin needle, courtesy of Novo Nordisk; c) additively manufactured sample.

Full text

4th Dimensional X-ray Computed Tomography Conference
25th-26th June 2019
University of Huddersfield
X-ray computed tomography surface topography measurement:
industrial case studies
Adam Thompson1, Nicola Senin1,2, Richard Leach1
1 Manufacturing Metrology Team, University of Nottingham, NG8 1BB, UK
2 Department of Engineering, University of Perugia, 06125, Italy
Correspondence email: adam.thompson@nottingham.ac.uk
Abstract
X-ray computed tomography (XCT) can be used for the measurement of surfaces and is particularly
applicable to the measurement of internal or otherwise difficult-to-access surfaces. Also, recent
research has shown that the lateral resolution achievable using XCT is approaching that achieved by
contact and optical surface measurement technologies. While XCT surface measurement has been
examined in a research environment during the past few years, application of the technology to
industrial cases has been less well explored. Additionally, XCT surface measurements have, thus far,
only been applied to relatively rough surfaces (i.e. where the arithmetical mean height of the scale
limited surface, Sa > 1 μm). Results comparable to those acquired using established surface
measurement technology have been acquired by measurement of these rough surfaces using XCT
systems, but little investigation has been performed on measurement of smoother surfaces. Recently,
industrial collaborators have expressed an interest in measuring smooth surfaces as part of the
European ‘AdvanCT’ project. Here, we present an investigation into XCT measurement of relatively
smooth surfaces (Sa < 1 μm), applied directly to a number of industrial cases (see figure 1a and 1b)
and compared to another case study presented in previous work (see figure 1c). XCT data are acquired
at the Danish Technological Institute and the University of Nottingham, and compared to coherence
scanning interferometry (CSI) data for the same surfaces. Characterisation is performed using
established and recently developed methods (ISO 25178-2 parameters and direct statistical
topography comparison, respectively). The results presented show the ability (or lack thereof) of XCT
to measure relatively smooth surface topographies, through comparison to optical measurements
made using CSI, given its lower lateral resolution of. The case studies presented here are designed to
provide further information about the capability of XCT systems for measuring surface topography,
particularly in an industrial context and for smooth surfaces. We would like to acknowledge Novo
Nordisk and 3TRPD for supplying case studies, and the Danish Technological Institute for providing
XCT data.
a) b) c)
Figure 1. Example industrial parts to be measured during this case study: a) animal mask; b) insulin
needle, courtesy of Novo Nordisk; c) additively manufactured sample.