Effect of Datum Securing Method on Precision of Mechanical Alignment System

Abstract

In this research, the achievable precision level using mechanical datums for manufacturing has been studied. Specifically, the effect of how a datum is secured in a mechanical alignment system was studied with the aid of a high-resolution multidimensional optical position monitoring system developed for the purpose. The study shows that the way datum is secured can be a major factor affecting the alignment precision of a mechanical alignment system. For a datum prepared by randomly inserting dowel pins into precision bored holes, a common practice in industry, the precision level was found to be worse than 10 μm. The results also show that the precision level can be readily improved by addressing this major cause of inaccuracy. Different methods depending on manufacturing requirements and constraints have been proposed. Some of these simple procedures lead to more than an order of magnitude improvement in alignment precision. [S1087-1357(00)02001-3]