There are some excellent reasons to use 5-axis CNC machines, but to really reap the productivity benefits you’ll need the right tooling and techniques—some of which are under the radar. We talk to three industry experts for timesaving and productivity guidance.
Whether your shop uses all five axes simultaneously or limits its machining to 3+2, 5-axis CNC machining centers are the best thing to happen to productivity since carbide. There are a host of benefits to using 5-axis machining including: reduced part handling, fewer fixtures, shorter lead times, higher part quality, the elimination of work-in-process, and making complex and otherwise impossible parts, such as knee implants and impeller blades.
Before diving all the way in, it is important to understand how part-making on a 5-axis CNC will be significantly different than the work on a 3-axis VMC or other system.
You may need entirely different tooling and workholding—and new strategies for setup and changeover. We talk to three industry experts for timesaving and productivity advice that is unique to 5-axis CNC systems.
5-Axis Machining Tip #1: Make Multiple Parts in Less Time with the Right Baseplate, Change Setups Quickly
One of the first negatives you might hear about 5-axis machining centers is the notion that they’re limited to one part per cycle. Not so, says Brad Evans, team lead for stationary workholding at Schunk.
“Many people overlook the ability to machine multiple parts on a 5-axis machine,” he says. “But if you equip your machine with a 45-degree pyramidal baseplate, you eliminate most of the interference problems and can machine anywhere from three to six parts per cycle, depending on the pyramid.”
Schunk’s KSC-series 5-axis vises are designed to mount on one of these SEP-style pyramids, but Evans acknowledges that anyone’s vise will fit. Special vises are another thing that some shops overlook.
Whatever the workholding and however many parts can be squeezed into the machine, though, Evans strongly recommends using a VERO-S or comparable zero-point locating system to reduce setup time and take full advantage of a 5-axis machining center’s flexibility.
“Due to their higher cost, it’s particularly important to keep the door closed as much as possible on a 5-axis machining center,” Evans explains. “So if you have a quick-change system and a three- or four-sided pyramid with a vise on each side, you can not only run the machine much longer between door openings but also switch to a different setup within minutes. You’re not dialing anything in or touching off—just drop the next job in and go.”
Find out why a trunnion system cannot compete with a 5-axis CNC and much more in “8 Important Facts About 5-Axis Machining Centers and High-Performance Machining.”
5-Axis Machining Tip #2: Use Toolpath Simulation
Multiple parts per cycle can raise the already high crash potential of 5-axis machining where long tool lengths and tight quarters increase the risk of interference.
Bad days due to machine collisions can be easily avoided—all it takes is a little additional effort up front, and a software package dedicated to making the most out of every machine tool, says Gene Granata, product manager for toolpath simulation software Vericut at CGTech.
“A lot of shops rely on their CAM system’s simulation capabilities to detect interference,” he says. “The problem here is that a program might check out just fine during toolpath development, but once it’s been post-processed, errors can be introduced.”
True toolpath simulation also verifies the entire machine tool, including travel limits, behavior of specific CNC control functions like dynamic offsets and cutter compensation, the ever-changing workpiece, the fixtures and toolholders, and even the clamps that hold the vise to the table. This level of realism and accuracy is difficult to achieve in any programming system.
Toolpath simulation provides much more than crash avoidance, however—it also increases machining efficiency. Because 5-axis machining operations are generally more complex than those performed on less-capable machine tools, many programmers—particularly those new to 5-axis work—retract tools much further than is needed to clear the workpiece.
They may also use a slow approach and slow positioning feed rates because they are not confident about how the machine will move or how close the tool really is to potentially colliding with something.
“They waste all kinds of time and motion doing that and go through extensive prove-out processes on the shop floor, whereas a good simulator shows you exactly what’s going on inside the machine and how it’s behaving,” says Granata. “This lets programmers stay closer to the part during positioning moves, which increases overall efficiency, while at the same time assuring the programmer that there won’t be any problems once the job hits the floor. The goal should always be first part, good part.”
Do you need a technical question answered? Ask the MSC Metalworking Tech Team in the forum.
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