A tool path error estimate in computer numerical control for five-axis machining

Material removal simulation for five-axis machining using a solid-based method shows animations of Numerical Controller (NC) milling as motions of a cutter. Due to the three-dimensional boolean operations between solids the simulation should run on a platform based on Graphic Processing Unit (GPU). We propose a new method of a tool path error estimate for five-axis machining using machining zones. The method can be integrated in Computer Numerical Controller (CNC) which usually has a low-level hardware. The main idea is actual motion control data (MCD) acquired from the interpolation processor of CNC make up a tool path, an original design is represented by a STL model and a estimate is performed by comparing the tool path and the STL model via machining zones. First, by building three machining zones of an original STL model using the extended octree clipping algorithm, a set of machining tolerance distance filed related with surfaces of the original model are determined. Second, MCDs can be converted to a tool path in the workpiece coordinate system using transformation matrices. Third, errors can be calculated which judge situations of machining, such as overcutting, undercutting and cutting. Finally, an experiment example will be given and shows the effectiveness.