Offline Force Control and Feedrate Scheduling for Complex Free Form Surfaces in 5-Axis Milling

An enhanced Force model based Feedrate Scheduling (FFS) technique for rough cutting of parts with complex free form surfaces in 5-axis machining is presented. In order to estimate the cutting forces in complex 5-axis machining an enhanced solid modeler kernel based model is developed to find the complicated engagement between cutter and workpiece for each cutter location. In this paper, cutter-workpiece engagement model is presented using the commercial Parasolid solid modeler kernel, and then cutting forces are estimated based on the developed model. In this approach, the resultant cutting forces are kept constant on a user defined threshold. The feedrate will be adjusted to keep the resultant cutting forces constant all along the tool path. Therefore, it is shown that this approach allows decreasing the cycling time drastically. The scheduled feedrate in each cutter location is carried out in NC blocks using an off-line postprocessor that can be used in commercial CAM software. Eventually, the proposed FFS technique is experimentally tested on rough machining of an impeller with free form surfaces and force validations are presented in this article.