Runout evaluation methods for cylindrical, tapered and flat surfaces

Modern metrology conducts measurements by recording discrete data on the manufactured part's surface. The ASME standard [1] for Geometric Dimensioning and Tolerancing (GD&T) however, defines tolerances for features of size rather than discrete data. Thus any kind of tolerance verification requires the development of computational techniques that can mathematically model the part's surface by interpreting discrete data clusters.;Runout is an important tolerance for axially symmetric parts. Traditionally, runout has been measured in the industry by means of a dial indicator, a labor intensive and time consuming process. The use of computational algorithms for runout evaluation has never been the main focus of any previous research.;This research presents novel methodologies for the evaluation of circular and total runout for two types of surfaces: surfaces constructed around the datum axis, and surfaces at right angles to the datum axis. In dealing with surfaces of the first type, the cases of both cylindrical and tapered surfaces have been considered, and separate algorithms for both have been presented. All algorithms have been implemented first on simulated parts, and then validated using a case study on real parts.;Runout is always specified with respect to a datum. Three cylindrical datum evaluation methods (DEM) have been studied in this research in terms of the runout results at various sample sizes. Three statistical metrics have been used as performance indicators. Trends obtained for simulated and real parts over a range of sample sizes have been examined, and recommendations have been made for the DEM to be used for runout evaluation based on accuracy, precision and true value estimates.