This paper presents a brief review of a leading commercial computer-aided tolerance (CAT) analysis system, VisVSA, which is available from EDS/Unigraphics. VisVSA facilitates statistical analysis of dimensional variations in parts and assemblies, based on Monte Carlo simulation. Tolerance specific entities and attributes are interactively extracted from CAD models. Feature attributes are varied within the specified tolerance range, and user-defined statistical distributions are used in simulation runs to determine the contributors, the extent of contributions, sensitivities, and statistical distribution of the analyzed part dimension or assembly clearance/interference. VisVSA represents the state-of-the-art in tolerance analysis, but the technology itself needs further advancement.

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