Uncertainty in measurement for x-ray-computed tomography using calibrated work pieces – R. Smith and C. Niggermann

X Ray CT/6

Abstract

This paper presents the principles of industrial x-ray-computed tomography (XCT) and its enormous potentials for the non-destructive 3D measurement and quality assurance of technical parts. Due to many overall factors and many nonlinear factors having an influence on the tomographic imaging process, the reconstructed volume model and thus the measurement results, XCT is a complex technology. Until now for XCT the uncertainty in measurement in general cannot be quantified satisfyingly regarding the traceability to national standards and the comparability to other measurement devices, eg tactile coordinate measuring machines. In this work different procedures to determine the uncertainty in measurement are assessed considering their applicability for XCT. The procedure of using calibrated work pieces is regarded as the most promising. This procedure is evaluated for an aluminum test part. The effect of several system parameters, which can be influenced by the operator, on the uncertainty in measurement is analyzed. The possibility of partially minimizing the analysis effort by means of simulation is outlined. In detail, for bore holes the effect of random errors on the measurement result is simulated.