The effects of x-ray computed tomography filament degradation on extracted areal surface texture data

The addition of x-ray computed tomography (XCT) to the arsenal of available surface metrology methods has proved particularly advantageous due to its ability to perform areal surface analysis of surfaces with no line-of-sight (optical or contact stylus). This technique has particular application for parts manufactured by additive manufacturing techniques (AM). The combination of the use of XCT for dimensional checks and extraction of surface topography has led to significant interest in XCT as a metrology tool. Recent research has led to the development of validation of the methods by which useable areal surface texture data can be extracted from XCT scans. Various factors effecting the values obtained from this process were highlighted previously. The paper highlighted a significant change to data following a filament change, this may be attributed to the filaments not being dimensionally identical, not being seated in the same position or possibly degrading during their useful life. Filament changes are a regular maintenance procedure carried out when using XCT machines this is due to the consumable filaments reaching the end of life. At the point where a filament has reached end of life its diameter will have decreased by approximately 5-6% [1]. This paper reports on a research program which has investigated the statistically significant changes to the measured surface texture data from a known surface, throughout the lifetime of an XCT filament. The results are presented in terms of changes to extracted areal texture parameters per ISO 25178-2 and show that during the filament lifetime the effects of filament degradation needs to be taken into account and a maintenance/validation checks need to be regularly carried out.