1. A method for determining excessive tolerances in the generation of NC parts programs comprising the steps of: converting a predetermined CAD geometry into a first grid, said first grid defining a first grid surface; generating NC program data of an NC parts program based on the predetermined CAD geometry; generating a second grid from the NC program data, said second grid defining a second grid surface; determining distance values between the first and the second grid; and rendering a visualization of one of the determined distance values and the distance values that exceed a predetermined tolerance threshold.