The four-axis numerical control (NC) configuration is suitable for the manufacture of a part family (called rotationally free-surface or RFS) requiring concurrent motions for the tool movement and part rotation. The authors develop algorithms for handling tool interference in four-axis machining in which three types of interferences exist: interferences due to step-size, tool-size, and tool-axis. The first two types are also present in three-axis machining, but the third type is unique and critical in four-axis machining. The performance of the algorithms was tested via graphic simulation and actual cutting. The results showed that the algorithms can be readily incorporated into existing CAD/CAM systems as a module for interference-free four-axis NC machining of a RFS.>

A prototype four-axis CAM module for the machining of industrial parts with rotational-free surfaces has been developed. The CAM module consists of geometric modeling of the rotational-free surface, CL-data generation, graphic simulation and verification, and postprocessing and communication. To test the validity and effectiveness of the developed module, several test cuts were made with an additional-four-axis CNC milling machine and compared with the graphic simulation.>