5-Axis Machining

Rolling Ball Method

The Rolling Ball Method (RBM) is a 5-axis method of positioning tools to machine curved surfaces. The RBM is a blend of the Principle Axis Method and the Multi-Point Machining method. It embodies the simplicity of PAM and multi-point machining with inbuilt gouge cecking of MPM. The basic premise behind RBM is to position an inflatable ball on the surface at the poi8nt to be machined. The ball will contact the surface at one point. Next start inflating the ball until it touches the die/mold surface at a second point. This ball is the largest ball that can be positioned at the point. This ball can be imagined to represent the die/mold locally and a tool position determined using MPM. Since the die/mold is modeled as a sphere the tool will contact it along a circular line of contact, but will never gouge it. The contact curve will pass through one point on the surface but will be very close to the die/mold at all other points on the curve. By connecting numerous such positions a RBM tool path can be generated.

Since RBM is a closed procedural technique, it is computationlly very fast and easy to implement. Further gains in speed can be made by using parallel algorithms.

Further work is ongoing on RBM as part of the Ph.D. program of P. Gray, and the research results can be found in:

Last updated on: September 19, 2014

P. Gray, S. Bedi, and S. Mann Rolling Ball Method for 5-axis Surface Machining Computer-Aided Design. Vol. 35, 2004, pg. 347-357
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