CNC machine tools are the multitasking proctors of precision manufacturing, representing mature technology and deployed across industries. However, development and application of new software may enable robots to steal a significant portion of the CNC machine tool market.

Last year saw countless news stories about robots, including here at the IMT blog. On the industrial side, the latest data available fared that the North American robotics industry posted 30 percent growth through the first three quarters. Indeed, manufacturers are changing the ground rules for robots at an amazing pace. Today robots are too successful to ignore and too affordable to overlook.

Typical applications of industrial robots include welding, painting, ironing, assembly, pick and place, palletizing, product inspection, and testing — all accomplished with high endurance, precision and speed. Yet new looks and tricks are being aggregated to industrial robots rapidly. Even now, multi-robot controllers are common, mobility is on the rise, and some units are being built with two arms on the same base. At Honda, Toyota and other companies, there have been huge investments in robots that walk, hop and jump…and may one day stand side-by-side with us in the workplace.

“Side-by-side with us” is likely quite a bit further into the future, perhaps even in later lifetimes…but will they replace our actual machine tools sooner? Specifically, our CNC machine tools sooner?

(CNC Milling Machine and Lathe, via Precision Aircraft)

A recent (punctuation-agnostic) headline at American Machinist dictated the following (punctuation included here): “Move over machine tools. Here come robots.” The article supposes the possibility of robots gaining CNC machine tools’ functionalities.

“Robots are poised to take away a significant portion of the CNC machine tool market,” a Robotics Online article declared in late 2005. “Emerging technology is making it possible for robot systems to perform many diverse manufacturing processes — such as complex cutting and material removal, grinding, mold creation, surface finishing, and drilling and tapping applications — that were previously performed by CNC machines.”

First, why even consider robots in CNC machining? CNC machine tools are the factotums of precision manufacturing, representing mature technology and deployed across various industries and applications. The use of robots in CNC machining saves money in at least three ways. In the typical robotic work handling application, the manufacturer realizes all of these savings simultaneously:

• Improved asset utilization;
• More efficient use of labor; and
• More consistent production.

“Robots are proving to be faster, more flexible and are much more robust and reliable when compared to standard industrial CNC machines,” according to Kevin McManus, president of Robotic Production Technology.

Robots as Alternative
Third-party CAD/CAM packages, in fact, have evolved to use process-specific tools for quick creation of complex cutting and material-removal paths. As such, these CAD/CAM programs have solved issues like drilling metals and rotation speeds, process-specific expertise regarding material-removal rates, cutting angles and optimized cutting paths.

The primary problem for robots as a proper alternative to CNC machine tools has been the lack of industry standards regarding robot manufacturers’ own proprietary programming language. “There is a classic failure to communicate in the machine shop. Robots run on brand-specific languages all their own, while conventional CNC machine tools read G-code generated through CAM software,” American Machinist notes.

As the CNC program standard — universally known as G-Codes — has fragmented and evolved over time, G-codes (motion) and M-codes (functions) used in CNC programs are defined variously. From a machine’s perspective, all of this process-specific knowledge built into the CNC programs ultimately produces a path, a speed and the orientation of the tool relative to the part,” Robotics Online notes.

Robots use the same kind of information in parts processing. To attain the expertise of third-party CAD/CAM packages developed for CNC machine tools, manufacturers found their answer to the lack of a universal proprietary programming language code: in software.

Says Robotics Online:

Individual CNC programs often contain tens of thousands of programming points, representing untold man-hours of program development. However, PC-based software now exists that easily and quickly translates programs written for CNC machine tools, including I/O and other non-motion commands, into robot programs that are ready to run.

This conversion is done offline — all of it, offline — so production remains uninterrupted.

While some translators (sometimes called post-processors) are specific to a particular industry and/or CNC process, other software translators have the capability to handle the variations in format and different G- and M-code meanings among diverse industries with only minor changes to the software configuration files.

In addition to an expected lower overall equipment cost, such CNC machine-tool program-conversion software enables manufacturers increased flexibility that five- or six-axis robots can offer, “as opposed to more expensive CNC machines with only three- to five-axes of motion.” Six-axis robots can perform many of the same tasks more efficiently, with a faster and cleaner process that provides high throughput rates and virtually unlimited flexibility. Some applications still will require the high tolerances and accuracies provided by CNC machines, but many do not require quite the same level of precision.

Currently, most shops do not associate even five-axis contour surface machining with robots, primarily because “it would take a great deal of time to teach a robot all the necessary data points,” says American Machinist:

Instead, shops use CNC machine tools. If the parts are large, they are split into multiple pieces that fit on the machines and reassembled after cutting. Alternatively, shops will remove machine panels and doors to mount the portion of the workpiece that needs cutting on the machine, while the rest of the part hangs out or over the sides.

(via Island One Society)

Even further, programming a robot to read G-code directly from a CAD/CAM program could enable the robot to gain the functionalities of a CNC machine tool.

A robot, if reading G-code directly from a CAD/CAM program, could be programmed in minutes to work on any three- or five-axis workpiece. Current technology typically requires hours, or even days, of programming before a robot is ready to work.

In the near term, robots already are replacing CNC machines in the secondary operations. Indeed, due in part to their range of motions, robots actually may be ideal for such operations. Robots may not be able to compete with CNC machines’ accuracy currently, but the programmability via new software tools nonetheless is a forward-moving development. It definitely is one that warrants notice.

References

Move over machine tools here come robots
by Charles Bates
American Machinist

Robots: The Lower Cost, More Flexible Process Improvement Alternative to CNC Machine Tools
by Greg Webb and Mary Kay Morel
Robotics Online, Sept. 19, 2005

Robotic Production Technology and FANUC Robotics America Announce AccuTrim Robots
Press relesase (via the Auto Channel), Feb. 24, 2006

Additional

The Changing Face Of CNC Programming
by Mark Albert
Modern Machine Shop, Aug. 5, 2005