Navigating the Tolerance Analysis Maze

This paper classifies and reviews geometric tolerance analysis methods and software. Two of the most popular methods, 1-D Min/Max Charts and Parametric Simulation, are reviewed in detail. The former is fully consistent with international tolerance standards but limited to decoupled analysis of variations in one direction at a time. It is also hard to automate. The latter can handle variations in all directions but is not fully compatible with the standards. The results are highly dependent on the expertise of the analyst. New methods are emerging to overcome these problems. One such method called T-maps is also reviewed. It maps geometric variations from physical space to 3, 4, or 5 dimensional virtual space and computes tolerance accumulations using Minkowski sums. The method so far has shown to be consistent with tolerance standards and can handle all tolerance classes applicable to planar and cylindrical features.