The need for nondestructive evaluation on large quantity production components is becoming more achievable with CT technology due to the advances in machine hardware and processing techniques over the past few years. Computed tomography, once a slow, tedious process, has grown into a nearly instant method of data acquisition. The cone beam CT approach paired with ever increasing data communication rates can allow for substantial (and reliable) data sets to be produced much faster; in some cases it can be 15 minutes or less. This article will discuss the use of a calibrated test artifact to demonstrate how scan time affects the ability to perform automated measurement techniques for large quantity screening applications. A series of scan times ranging from five minutes to three hours will have an automated measurement template applied and repeated for five instances. The variation between each of the five measurement outputs will be used to decide the optimal scan time for this object. This type of benchmarking can be used to evaluate the optimal scan times for any component that may require a large inspection quantity. By investing time in the setup, the overall goal is to reduce unnecessary time and cost associated with each of the subsequent scans while still maintaining quality and precision.
A calibrated ruby sphere assembly was utilized for this benchmark study. A total of five scans were performed at the same magnification: five minute scan, 15 minute scan, 30 minute scan, one hour scan and three hour scan. The software was used to define and fit spheres onto the scanned assembly where the measurements were then saved as a template in the established coordinate system. This measurement template can be thought of as virtual CMM probing that can be imported and applied to a registered data set. The distance between each sphere was the reported measurement that was studied.