STEP-NC in Support of Machining Process Optimization

Abstract

Machining process optimization is the selection of machining parameters for a given process to achieve the maximum material removal rates within the process and machine limitations. Since the majority of those limitations directly relate to the cutting forces generated during the machining process, accurately calculating these cutting forces is not only critical to the optimization effort but also to the preservation of the equipment used in process. Calculation of the cutting forces requires knowing the cross-sectional geometry of each tool path over the course of the machining process. Although this geometrical information is available when three-dimensional (3D) modelling is applied in modern CAM systems, there has been no direct means to extract this information for use in the cutting force calculation and process optimization, until the recent work on ISO 10303 AP 238 (STEP-NC). This application protocol provides a new data model to transfer product data from CAM systems to computerized numerical controllers (CNC). It also contains the necessary data structure to implement the tool path geometry information into the process optimization. This protocol offers an unprecedented opportunity to control and manage the machining process based on explicit in-process information contained in the model that was previously unavailable. In this chapter, the fundamentals of cutting force calculation are explained, the tool path cross-sectional geometry in machining operations and its parameterization in ISO 10303 AP 238 are illustrated, the basic principles of force based optimization are described, along with a depiction of the optimization implementation plans. All of this demonstrates the vital role ISO 10303 AP 238 plays in machining process optimization.