Computed tomography enabling virtual assembly

Computed tomography (CT) is the only dimensional measurement technology that captures holistic geometric information of the complete object. The availability of equally and densely distributed measurement data gathered by CT enables the consideration of local form deviations of the object's surface for the definition of a datum system. A datum system describes a coordinate system that is used for referencing geometrical tolerances. Therefore, the datum definition by an approximation of datum features is replaced by a fitting method called virtual assembly (VA), where the datum surfaces are registered in order to simulate the real, physical workpiece contact. Besides describing the theory, in this paper the method is evaluated using a linear guide assembly as an example that is compared to the real assembly of the object.