Metrological study of CFRP drilled holes with x-ray computed tomography

The popularity of composite materials is continuously growing with new varieties being developed and tested with different machining processes to establish their suitability. Destructive as well as non-destructive methods, such as ultrasonics, X-ray radiography and eddy-current, have previously been used to ensure that the combination of particular machining methods and composites provide the required quality that can allow the required lifespan of the final product. X-ray computed tomography (CT) is applied as a novel method in this paper to obtain quantitative data about the inner and outer structures of carbon fibre reinforced polymer (CFRP) drilled holes providing more information than any other non-contact and non-destructive evaluation. This is combined with precise measurements from optical CMM and image processing for a full analysis for the entire part. This method can provide accurate measurements for all the layers of the CFRP and very little interaction from the operator minimising the human error. The method complies with VDI/VDE 2630 standard and the quality of the acquired measurements is assured. The results can assist in establishing the best machining process, provide accurate measurements of diameter, circularity and positioning of the hole and information about delaminated areas.