No matter how easy to operate, few would argue that five axis machining centres are more prone to tool and fixture interference than those limited to three axis work.
Gene Granata, Vericut product manager for software provider CGTech Inc., says accurate toolpath simulation driven by the same NC code that will ultimately drive the machine is important for any CNC machine tool, but especially so as their complexity (and capabilities) increase.
“Whether you’re doing multi-axis simultaneous, or 3+2 machining, what often happens is that the programmer plays it safe,” says Granata. “You have a rotary table that’s spinning, or a head that’s tilting this way and that, and it becomes a real challenge for someone to figure out what happens when you’re moving a tool from position/orientation A to position/orientation B. Many times they end up pulling well clear of everything during a positioning move to minimize risk of collision, but also wasting lots of time and machine motion. With a good simulation product, you have a precise understanding of your machine behaviour, and can stay close to the part without worry. This makes machining much more efficient as well as collision-free.”
For those companies considering the purchase of a five axis machining centre, Granata strongly recommends simulating several representative part programs as part of the evaluation process; because most machine tool builders provide downloadable 3D models of their equipment, building a virtual machine that you can “test drive” is not the challenge it once was.
“There are so many machine configurations available these days that even experienced five axis shops might not immediately understand which one is best for a certain application,” he says. “Simulating the environment before actually pulling the trigger on a new machine purchase helps prove that it, along with your anticipated workholding and tooling, can actually reach all of the part features you need to, and there won’t be any interference with a gear box or a piece of sheet metal. It can mean avoiding buying the wrong machine for the job, which could be a half-million dollar mistake.” SMT
