Effect of Manufacturing Tolerances and Assembly Errors on the Characteristics of Small Scale Slider Crank Mechanisms

Small scale slider crank mechanisms are used in many sophisticated applications, where the accuracy and precision of the mechanisms function are their main performance criteria. The input-output of the mechanism are the main criteria to define its characteristics and hence its capabilities to achieve specific application requirements. The tolerance analysis for the mechanism components are a key element for studying and improving mechanism characteristics and its transmission quality. In this paper kinematics contact approach models for small scale slider crank mechanism are presented. The models consider the mechanism characteristic range, sensitivity and input-output relations. The effect of mechanism manufacturing and assembly errors such as; components tolerances, revolute joints clearances and assembly deviations were investigated. The investigations are applied for the inline and offset types mechanisms. The study elaborates the effect of these errors on the mechanism characteristic, position errors and uncertainty. The effect of revolute joints clearances and offset on the mechanism hysteresis errors, position uncertainty, and dead zones are presented. The results of the proposed contact models are compared with those applying Ting rotatability method. The study is further condensed to define the most appropriate design parameters and manufacturing tolerance according to the permissible system errors.