Study on the Evaluation Method of Angularity and Position Errors for Plane Features

The plane features of part drawings may have such indications as angularity tolerance and/or position tolerance and additional symbols. In this paper, twelve kinds of angularity tolerance drawing indications and twenty-eight kinds of position tolerance drawing indications were given, and the evaluation models of angularity error and position error were established. Based on the models above, the program for evaluating angularity errors and position errors of plane features was developed. The simulated profiles of plane features for two samples were taken as an example, and twelve cases of angularity errors and twenty-eight cases of position errors were evaluated and analyzed. The analysis of the evaluation results showed that the evaluation results of partial angularity errors and position errors are quite different under the same datum plane and the same measured object, and both datum plane and toleranced object have obvious influences on the evaluation results of angularity errors and position errors. This research may help designers understand the meanings of angularity tolerance zones, position tolerance zones and their additional symbols and indicate drawings reasonably.