Research Shows Gains in Milling Productivity

February 1, 2010

Cutting tool and machine tool technologies have become more sophisticated over the years, but some experts believe full productivity gains have not been made because of the inherent shortcomings in the offline generation of tool paths.

Research at GateWay Community College, Phoenix, Ariz., involving tool path software provider Celeritive Technologies and tool manufacturer Helical Solutions shows that a cutting tool can increase metal removal rates as much as 10 times if it’s driven by innovative tool path programs.

“No matter how sophisticated a machine tool is, it can’t do anything without a tool and a tool path,” said Glenn Coleman, chief product officer and co-founder of Celeritive Technologies, designer of the VoluMill tool path software used in the GateWay testing. “The tool path has always been the weak link in the chain, typically forcing the use of cutting parameters that err on the side of caution rather than productivity.”

When numerical control (NC) came along more than 50 years ago, programmers tried to replicate what a skilled machinist could do turning crank handles. Problems become obvious every time there’s a sharp corner in the tool path, where the load on the tool increases because the tool is bearing into more material.

“There have been many attempts over the years to improve upon the traditional tool path,” Coleman said. “Most of those, however, are still based on the fundamental pick-geometry-and-offset-it method. There are detect-and-adjust approaches out there that try to help along a path that has flaws, but the VoluMill approach is to generate the tool path so that the flaws are never there in the first place.”

Four problem areas limit machining throughput when using traditional tool paths:

1. The initial full cut
2. Stepping over between cuts
3. Feeding into new areas of the part
4. Overloading in corners

The new software utilizes existing CAD/CAM functionality for geometry and input/output functions, allowing customers to continue using their CAM system of choice. It manages cutting strategies, feed rate, and depth of cut and minimizes force and heat buildup in both the part and the tool by maintaining the programmed material removal rate.

“What we have done with VoluMill is devise a different way of driving the tool through the material,” said Coleman. “We’ve developed a path that will ensure a consistent load on the cutting tool. We’ve embedded ways to address all instances of the problem areas indigenous to traditional tool path technology. As necessary, VoluMill makes dynamic adjustments to the depth of the cut and/or the feed rate so as to never exceed the preset volume of material being removed at any given time.”

For more information, visit www.1helical.com and www.celeritive.com.