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Automatic Five-Axis CNC Feedrate Selection via Discrete Mechanistic, Geometric, and Machine Model Integration

The purpose of this research is to determine feasibility and develop software tools for automatically generating adaptive feedrates for use in five-axis CNC end milling. The complicated part geometries often involved with five-axis milling, combined with the rotational degrees of freedom of the machines, make it difficult to manually estimate acceptable feedrates without being overly conservative. Our approach for automatic feedrate generation is to use a computer simulation of the milling process. This software estimates the feeds required to maintain a desired peak cutting force on a per-tool-move basis, and consists of three distinct portions: a discrete mechanistic model, a discrete geometric model, and a model of the specific CNC machine on which the part is to be cut. The mechanistic model estimates cutting forces as a function of cut geometry, cutter-to-stock relative velocity, and material constants. Used in an inverse manner, the mechanistic model may be used to estimate the feedrates necessary to maintain a constant peak cutting force. This force value may be selected to prevent cutter breakage, maintain a desired part tolerance, or to meet some other criteria (e.g. machine constraints). The results of this research have shown that it is possible to automatically generate adaptive feeds that maintain a desired force level using these combined models.

Recent Publication

J.G. Hemmett, B.K. Fussell, and R.B. Jerard, "Automatic 5-axis CNC feed-rate selection via discrete mechanistic, geometric and machine model integration," Machining Impossible Shapes IFIP TC5 WG5.3 International Conference on Sculptured Surface Machining (SSM98), Ed.. B. Choi, R. Jerard and G. Olling, Nov. 9-11, 1998, Chrysler Technology Center, Kluwer Academic Publishers, 1999, pp. 138 -146. (paper in pdf format)