8 Important Facts About 5-Axis Machining Centers and High-Performance Machining

Are you unsure about the value of 5-axis machining for your machine shop? Look no further than this helpful list of factoids that is sure to help guide you through its benefits.

Perhaps your shop is thinking about acquiring 5-axis CNC machines. Or perhaps your shop already did and you’re still figuring out the best way to program the machine and tool it up. Whatever the case, there’s a lot to consider if you’re going to make the most effective use of these ultra-productive machine tools.

Mastering 5-axis machining promises greatly improved part quality, reduced work-in-process and lower fixture costs, but it does require some new ways of thinking. Before you travel much further down the 5-axis road, consider the following concepts—some serve to dispel the rumors around this important machining technology, while others are simply designed to get you off to a running start.

1. You Don’t Need 5-Axis Work to Justify a 5-Axis Machining Center

Do I need a machine? Many shops hesitate to make the considerable investment in a 5-axis machining center because they’re not making the turbine blades, blisks, orthopedic implants and similar parts that are plastered over the front of any 5-axis machine brochure. Don’t worry about it; you generally don’t need simultaneous 5-axis work to justify a 5-axis machining center. Any part that gets machined on more than one side will benefit from the reduced part handling that comes with 3+2 machining, allowing completion of five of the six sides of most any orthogonal workpiece.

2. 5-Axis Machining on a Multitasking Lathe Might Be More Effective Than on a 5-Axis Machining Center

Maybe your parts are more round than they are orthogonal but still contain features that lend themselves well to 5-axis machining. It might be time to consider a multitasking lathe or 5-axis mill-turn center. These offer much of the same functionality as 5-axis machining centers and are able to produce complex, multisurface workpieces, but because they often carry a secondary spindle, many parts can often be completed in a single operation.

“I have seen great advantages using mill-turn machines,” says Dr. Thomas Kurfess, a professor and the HUSCO/Ramirez Distinguished Chair in Fluid Power and Motion Control at the ‎Georgia Institute of Technology. “However, to really leverage these machine tools, you really have to think outside of the box. Mill-turn machines are much more than a mill and a lathe combined; they offer a compact and much more repeatable 4- or 5-axis machining system that has a very unique and versatile configuration. Plus, they have a relatively small footprint, making them ideal machines for those who know how to leverage their advantages.”

3. Why You Cannot Use a Trunnion Instead of a 5-Axis Machine

Perhaps you’re thinking that you’ll slap a tilt-rotary trunnion table on one of your 3-axis vertical machining centers, thereby eliminating the need for a 5-axis mill. There’s nothing wrong with this approach and it is a good way to get started with 5-axis machining, but just bear in mind that a dedicated 5-axis machine tool carries control options such as tool center point control (TCPC), 5-axis auto-tuning, dynamic work offsets, and other features designed to make setup fast and easy, never mind a far more rigid, accurate machine construction. Simply put, a trunnion-equipped 3-axis VMC cannot compete with a true 5-axis machining center.

“Adding a tilt rotary trunnion table is a great way to transition to 5-axis machining,” explains Kurfess. “However, if you purchase a 5-axis configuration from an OEM, the machine and its supporting systems are fully integrated for 5-axis operations, resulting in smoother programming and workflows.”

4. All 5-Axis Machining Centers Are Not Alike

Speaking of machine construction, be aware that in 5-axis machining land, not all machine tools are built alike. Three distinct styles of machine are available— those with tilt-rotary tables integrated to what is basically a 3-axis machining center; those machines with an integrated tilt-rotary but are using a traveling X-axis column—and those machines where the milling head swivels left to right above a rotary table-equipped bed. Each has its pros and cons, and buyers must consider things such as tool interference, workpiece size, required part accuracy and machine cost to make the best decision for their particular application.

Once you’ve adopted 5-axis, you will want to know how to get the most out of it. Here’s some excellent guidance in the article: “Learn How to Push Your 5-Axis Machine’s Output.”

5. Fixturing Multiple Parts Is Easier Than You Think: You Are Not Limited to Single Parts

You might have heard that 5-axis machining means you can only produce one part per machine cycle. Not true. Granted, the most common method for gripping parts on a 5-axis machining center is a single, extended height vise that clamps a pre-machined dovetail at the bottom of the workpiece blank. But for those who need to machine 3, 4, 6 or more parts per cycle, there are an increasingly broad array of workholding options available. The result is that fixturing multiple parts on a 5-axis machine is easier and more flexible than you might think.

Kurfess puts it this way: “Not only are there a wide variety of excellent fixtures for 5-axis machining, many of them are nicely integrated into the programming capability of the machine, enabling even greater productivity of your fixturing. Once again, this is a significant advantage of purchasing a true 5-axis system.”

6. You Don’t Have to Dovetail Your Own Blanks

Did someone say dovetail? If you’re dreading the thought of not only having to saw workpiece blanks but then cut the dovetails on them as well, you might consider focusing on what you’re best at and ordering pre-cut, pre-dovetailed material from your steel supplier. You should also take a look at vises that rely on a series of pins, knife edges or even photo-activated glue to securely hold workpieces in place.

7. Improved Accuracy, Less Handling with 5-Axis Machining

Consider the traditional machining methodology whereby a 6-sided part requires six separate handlings and multiple fixtures to complete. As any machinist knows, no matter how well-designed the fixture, some small amount of part accuracy is lost with each operation. Since 5-axis completes all but the bottom of the workpiece without repositioning the part, the only thing preventing perfect accuracy is the machine tool itself.

8. ‘Done In One’ 5-Axis Machining Is Fun

A well-known machine tool builder suggests that adopting a “done in one” machining approach is one of the best things you can do for your shop’s bottom line. They’re right. With 5-axis, the baskets and bins of partially completed workpieces sitting around the shop are history. Cash flow is improved. Lead times are reduced while flexibility is increased. The burrs created when breaking into an intersecting feature are easier to remove.

“Not only do 5-axis machines help to reduce work-in-process, they also allow companies to better utilize their highly trained workforce and equipment,” says Kurfess. “First, a part and machine are not spending idle time in load and unload operations. Second, skilled operators are not performing low value added functions such as load/unload. Rather, they can spend time programming and setting up other machines as necessary.”

You might still scrap out a workpiece now and then, but you’ll discover it sooner rather than later. Simply put, 5-axis is the best thing to happen to machining centers since automatic toolchangers.