Process behavior charts used to check the consistency of CT instruments

Abstract

Digital manufacturing is one of the enabling methodologies associated with the concept of flexible mass customization, which has been boosted by the recent advances in Additive Manufacturing (AM) technologies, from which complex freeform geometries, internal and reentrant features can be reproduced based on the CAD model. From the standpoint of coordinate metrology, AM calls for a measurement technology capable of acquiring high data density of these complex structures. Computed Tomography (CT) is the technology of choice to holistically measure them and respond to the needs of mass customization. However, due to the complexity of the CT measurement chain, the numerous influence factors, and their difficult quantification, the measurement uncertainty evaluation remains an issue yet to be resolved. In this regard, one topic that has received attention is the determination of the geometric errors of the CT instrument, which cause errors to dimensional measurements. Using an imaging method to quantify the geometric errors, process behavior charts are detailed and used to check the consistency of the CT measurement process with regard to the geometric errors. The utilization of process behavior charts is the major contribution of this work since they allow us to operate the measurement process up to its full potential, and to evaluate the actual effectiveness of the imaging method to quantify the errors.