In order to perform an accurate tolerance analysis at the product level the true assembly behavior must be modeled correctly. The typical assembly constraints found in most CAD systems have been optimized for efficiently constraining parts in the idealized design configuration. They are not meant to account for the small kinematic shifts that occur in the assembly due to manufacturing variation. Additionally, traditional kinematic modeling is done in the nominal state using idealized representations of the relative motion. Since tolerance analysis must understand how the assembly will respond to variation, both of these traditional approaches have their limitations. In this webinar we will dig into some the technical aspects of the assembly constraint modeling used by CETOL and why it is important for proper tolerance analysis.