Investigation of the smoothing effect of focal spot size and voxel size on the XCT measurement of AM surface texture using surface amplitude transfer function

  • Xiao Chen (Speaker)
  • Jiang, J. (Contributor to Paper or Presentation)
  • Wenjuan Sun (Contributor to Paper or Presentation)
  • Lou, S. (Contributor to Paper or Presentation)
  • Scott, P. (Contributor to Paper or Presentation)
  • Zeng, W. (Contributor to Paper or Presentation)

Activity: Talk or presentation typesOral presentation


X-ray computed tomography (XCT) is a promising surface metrology tool for additively manufactured (AM) parts. But the metrology capability is influenced by the image unsharpness, which is significantly affected by the limited focal spot size and voxel size and results in a smoothing effect on the measured surface texture. To investigate the smoothing effect of the two factors, physical and simulation experiments were conducted using NPL’s 3DRS prototype sample. The smoothing effect was evaluated by the surface amplitude transfer function (SATF), where the surface smoothing size was characterised by the frequency corresponding to 50% SATF value. The simulation results show a linear relationship between the focal spot size and the surface smoothing size when the focal spot size is larger than the voxel size. The physical experiments show a non-linear relationship, which is considered due to other significant energy-dependent influencing factors in the physical experiments. Both simulation and physical experiments show an apparent linear relationship between the voxel size and the surface smoothing size. But the smoothing effect due to voxel size has a greater impact on surfaces with lower Sa, and the variance of surface smoothing size on surfaces with different roughness decreases as the voxel size decreases. The dependence of the voxel smoothing effect on surface roughness is considered due to the non-convolutional nature of the voxel smoothing process.
Period16 Jun 2022
Event title6th Dimensional X-ray Computed Tomography Conference
Event typeConference
Conference number6
LocationManchester, United Kingdom
Degree of RecognitionInternational