A comprehensive methodology for runout tolerance evaluation using discrete data

Abstract

Runout is a composite tolerance that is usually specified to ensure proper alignment and rotational accuracy for axially symmetric features. The procedure for evaluation of runout defined in American Society of Mechanical Engineers (ASME) Y14.5M-1994 [1] and International Organization for Standardization (ISO)/TR 5460-1985(E) [3] depicts the rotation of a part around its datum axis while a dial gauge measures the variations in the feature’s surface. These standards do not address the evaluation of runout using modern measurement technologies using discrete point clouds that dominate the metrology industry. This research presents a comprehensive methodology for evaluating runout tolerance using discrete data that closely replicates the requirements specified by the ASME and ISO standards. This work builds upon previous work by the authors, reported in Turek et al. [9] and presents a comprehensive methodology for evaluating circular and total runout for flat, tapered, and cylindrical features using discrete data. The methodology was tested using simulated datasets and the analysis reaffirmed the results reported in Turek et al. [9] regarding the choice of minimum circumscribing cylinder as the preferred datum axis evaluation technique. Subsequently, the approach presented in this paper was applied to discrete data acquired from two manufactured parts. The results obtained were compared with traditional runout measurements acquired with a dial gauge. This comparison required the filtering of the discrete data to compensate for the finite radius of the dial gauge tip, and led to the development of a novel filtering technique to appropriately compare results. The results using the filtered data closely match the results obtained from the dial gauge, confirming the accuracy of the presented runout assessment algorithms. This work presents a first step in assessing runout using discrete data and justifies the use of modern metrology techniques in runout evaluation.