Applying the Coordinate Tolerance System to Tolerance Stack Analysis Involving Position Tolerance

Geometric dimensioning and tolerancing (GDT) has been playing an important role in specifying the geometry of part features during the product design stage. Tolerance stack analysis is then used to study the conformity of the parts to the tolerance zone. Performing stack analysis is time consuming because geometric tolerances are complex to compute. This paper presents a technique to formulate the bonus and shift tolerances (due to positional callout) and convert them to equal bilateral expressions as in a coordinate tolerance system. An example is used to demonstrate the effectiveness of the expressions. The usage of the expressions is less conceptual and this makes the application simple and direct. Most importantly, the results are shown to be accurate and reliable.