# 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)