A novel approach to determine the undercut free parting direction of a given mold part, in B-rep format, by using the accessibility of each of its surface is presented. The proposed system is designed to classify planar, ruled and freeform part surfaces based upon the criteria of their accessibility relative to the specified directions. The orientation of each surface with respect to the considered direction is used as an input for the accessibility analysis module. To analyze the accessibility, the surfaces are swept in the different directions, based on their orientation, to form solid bodies. A number of regularized Boolean operations are performed on the swept bodies. Then, volume and geometry-based constraints are applied to classify the part surfaces based on the accessibility. Using the results of accessibility analysis in a given set of directions, feasible mold parting directions are determined. The method has been successfully implemented and tested on benchmark parts.