The modeling of mechanical systems with manufacturing errors is a necessary task for engineers in order to predict the realistic functioning of a product during the design stage. Several tolerancing methods are proposed considering several defects such as dimensional and geometrical deviations. However, form defects are not considered or modeled using complex theoretical and mathematical models. In this paper, CAD-based methods are proposed for the modeling of planar parts with flatness defect. The Gaussian Perturbation Method is used to deter-mine random positions of points of a toleranced face considering the flatness tolerance zone value. Two CAD methods based on the use of the Scan To3D tool capabilities and the B-spline interpolation are presented for the final reconstruction of realistic faces with defect. Several algorithms are presented to update the initial coincident mates between planar parts with form tolerance.
