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Simply Complex PUBLIC ACCESS

CAM Keeps Speed and Efficiency at their Max in Today’s World of High-Speed Multitasking Machines.

[+] Author Notes

Contributing Editor

Mechanical Engineering 128(01), 28-31 (Jan 01, 2006) (4 pages) doi:10.1115/1.2006-JAN-2

This article focuses on industrial benefits of computer-aided manufacturing (CAM). With the ever multiplying functionality of both machine and software, the challenge for CAM programmers has become one of ‘how do you keep things simple and at the same time complex.’ Machine makers now work directly with CAM programmers so customers can get as much from their machines as possible. NX's newest software offers tool paths that are smoother and smarter, and take into account the material that's being cut, to better avoid collision. But the key to optimization is understanding every aspect of a machine, down to when and how it vibrates. Simulations let programs like NX and Vericut know every stage of a part while it is on the machine and this allows users to eliminate one of the most tedious of time drainers: documentation. NX software as well as Vericut automatically outputs documentation for the entire process.

Five years ago, when the engineers at Smiths Aerospace, in Yakima, Wash., wanted to make a cylinder used on an actuator for landing gear, the production process could take months. With bosses, lugs, bearing holes, and bearing flats, the piece would have to visit several machines, each of which would have to be programmed separately.

“It would take several weeks to program, and several weeks to machine,” said Bob Curwood, the company’s numerical control programming supervisor. “Now we can program it in less than a week and machine it in a day.”

This giant leap in speed and efficiency is largely due to a blossoming of high-speed multitasking machines, high-speed milling machines, and indexable carbide tooling. But unlike the machines of a decade ago, which could be programmed by hand, today’s whiz-bang tools are useless without computer-aided manufacturing software that knows how to take advantage of everything they can do. And, in many cases, the advances in CAM are just as stunning—and time-saving—as the hardware they support.

This X box was machined at Mastercam’s machine tool shop at the company’s Tolland, Conn., facility to test the speed and precision of the tool paths in the newest version of its software, Mastercam X. The program made the tool path automatically—safer, more efficient, and faster than ever before.

Grahic Jump LocationThis X box was machined at Mastercam’s machine tool shop at the company’s Tolland, Conn., facility to test the speed and precision of the tool paths in the newest version of its software, Mastercam X. The program made the tool path automatically—safer, more efficient, and faster than ever before.

With the ever-multiplying functionality of both machine and software, the challenge for CAM programmers has become one of “how do you keep things simple and at the same time complex.”

Any machinist who introduces one of today’s new machines to his shop will need a CAM program that’s as cutting-edge as the machine itself, but at the same time, is easy enough to use so that efficiency is maintained at every level of the part-making process.

Technological advances in the field are helping manufacturers in the United States and other developed nations achieve efficiency and speed that let them compete with low-wage rivals in the developing world.

“In a 100-year-old business you’d think we’d have done everything, and would pack up and go home,” said Vynce Paradise, director of marketing for NX machining at UGS, located in Maryland Heights, Mo. “But it’s astonishing where we can improve in the drive to be efficient, to beat other parts of the world.” When a cell phone manufacturer can have a mold made in China for what it costs a machinist in the States to buy the steel, the single advantage a U.S. shop may hold is the ability to turn things around quickly.

When multitasking machines first started appearing on shop floors, manufacturers weren’t always able to maximize the efficiency the machines were capable of, since they often didn’t have the tools to program them effectively. “Ten or five years ago, the makers of the tools didn’t care about us,” said Paradise. “They wanted to sell machines, not software. But the machine shops buy the machine tool first. It often sits there for three months. No one knows how to program it, or they program it by hand. Sometimes the machines had to be returned. Not to have them work isn’t good for business.”

What is good for business is having programs available for immediate use with specific machines. Machine makers, realizing this essential fact, now work directly with CAM programmers so customers can get as much from their machines as possible. NX, for example, has worked directly with companies like Mori Seiki, Makino, and Mazak so that shop owners can have a machine that can be programmed the day they buy it. And Gibbs and Associates in Moorpark, Calif., maker of GibbsCam, has worked with machine manufacturers to have its software installed on the machine tool controller itself. Machine makers and users alike have come to realize that the complexity of today’s tools make computer assistance, once a luxury, a necessity.

From flat to phat in minutes: Mastercam Art is an add-on that lets users turn 2-D images into 3-D sculpture with as much detail as the user needs.

Grahic Jump LocationFrom flat to phat in minutes: Mastercam Art is an add-on that lets users turn 2-D images into 3-D sculpture with as much detail as the user needs.

This necessity is apparent in things as basic and crucial as the retraction of a tool after an operation. Traditionally, on a three-axis machine, tools would have to come to the top of a part after making a single cut before going on to another spot for the next. Now tools on a five-axis machine can make much shorter and speedier tool paths, with the cutting tools coming off the part only just enough to clear the material and moving in a path much closer to a straight line.

“That might sound trivial, but to the guy cutting the part it means getting into the cut faster and getting the part off the machine faster,” said Ben Mund of CNC Software Inc., the Tolland, Conn., developer of Mastercam.

Programs like Mastercam make the computation and execution of that path, and any other tool path, automatically. A programmer who wants to make a change to the tool path can do it instantly. Similarly, NX software allows users to measure a part as it’s being made and offsets can be changed on the fly.

CAM can also be an integral part of making a high-speed machine perform at the high speeds it was meant to.

“What we often see happening is on the high-speed mills, people get scared of them,” Paradise said. “The boss of the shop got great expectations when he saw it in the show, but when it came into his shop, his people couldn’t deliver on it—and the reason is they start breaking tools and they don’t understand why. The natural reaction is to turn the feed and speeds down until it stops breaking tools.”

NX’s newest software offers tool paths that are smoother and smarter, and take into account the material that’s being cut, to better avoid collision. But the key to optimization is understanding every aspect of a machine, down to when and how it vibrates.

“We applied for a patent on a method for how users ascertain what the best feeds and speeds would be on their high-speed machines to avoid vibration. Once you’ve plotted those routines, you may well find that you can turn the speed up to a much higher level, and actually you go beyond the speed where you had problems, into a scenario where you don’t get any natural frequency vibration anymore,” Paradise said.

What could be more efficient than first having a process and a part tested entirely—from the CAD drawing to the actual part production—in virtual space? If the machine, the part, and the tool paths are accurately simulated, then the programmer will have a pretty good idea if things will run smoothly or not on the real machine. And when it comes time to make the actual piece, he has a much better chance of getting it right the first time.

“What we try to do is simulate by reading back the exact codes that would go to the machine tool from the NX post-processor,” said Paradise of UGS. “Do that on the fly, then feed it back into the software, and use that to drive the model. That gets us as close as we can get to what the tool will do.” A plug-in version of the machine, calibrated from the machine itself, can be added to the CAM system. Since it brings in acceleration and deceleration from the head of the machine tool, users have a better idea how long it will take to make a part. They also learn -in a virtual trial run whether there’s any risk of a collision or some other error.

“To use the machine as a test bed is kind of stupid,” Paradise said. “In that case, someone could be machining titanium or high-end alloys, and these days it’s very expensive with a lot more machining from solid blocks. You don’t want to get it wrong—you could kiss goodbye twenties of thousands of dollars of material.”

A program called Vericut provides a similar simulation that can run from code coming from different CAM programs. “We run the actual NC code that runs the machine—a pretty significant difference,” said Bill Hasen-jaeger, the product marketing manager fôr CGTech, the developer of Vericut in Irvine, Calif. “We like to use the term ‘checking you own homework’: If you use your CAM program’s checking system, you’re using their software to check their own software.”

According to Hasenjaeger, Vericut’s simulation capabilities are detailed enough to find new pockets of efficiency, allowing programmers to push their machines to the limit. “If you know you can get away with 2,000 rpm and 30 inches a minute for a 2-inch depth of cut, we can take that and generalize,” he said. “When you encounter conditions that are shallower, it will speed up proportionally; when you cut deeper, it will slow down proportionally.” Simulations let programs like NX and Vericut know every stage of a part while it’s on the machine and this allows users to eliminate one of the most tedious of time drainers: documentation.

“Some of the peripheral stuff programs use is phenomenal,” said Curwood of Smiths Aerospace. “It may take you 10 minutes to drill a hole, but four hours to put all the documentation together.”

NX software, as well as Vericut, automatically outputs documentation for the entire process. According to Hasenjaeger, “We can automatically create a PDF or HTML that documents all the information of the process that was just simulated. That includes a list of tools that you used, the volume of material removed, the time each tool took, a picture of the workpiece and machine at every stage of the process, the programmer’s name, and a sequence of events.” CGTech has also enhanced an addon that wih allow users to have a CAD model of the actual part, after it is made.

All the extras, to say nothing of the intricate tasks and greater functions that make up the meat of a CAM program, can make the interface potentially unwieldy.

“The paradox is, people want both things,” said Mund of CNC. “They want the software to be extremely simple, but they want it do everything. You can’t do both things. It’s counterintuitive.”

The solution to this problem for Mastercam is to have hidden power. In the newest version of he software, Mastercam X, the basic tools that 90 percent of the customers use are found on the front page. More refined tools for more complex and specific tasks can be found elsewhere.

“We kind of have the philosophy of looking at it like a high-end Swiss Army knife,” said Mund. “If you buy one with one blade, you’ll outlive its usefulness. Yet you’ll still need the simplicity. You don’t have to use all its power, but when you need it, it’s there.”

CAM systems like UGS's NX let users synchronize multiple operations on something as complex as a mill-turn (left). What once took several machines, now takes only one. Potential errors can be spotted readily with simulations that are run from post-processed code (right).

Grahic Jump LocationCAM systems like UGS's NX let users synchronize multiple operations on something as complex as a mill-turn (left). What once took several machines, now takes only one. Potential errors can be spotted readily with simulations that are run from post-processed code (right).

To tackle the increasing issue of simplicity vs. complexity, NX has developed a set of “wizards” like those found in many Windows products. Using a series of either/or questions, these helpers can assist the user in accomplishing tasks. “In the past, you had to be a C programmer or a Visual Basic programmer. Now we have a loading tool wizard, a milling wizard, a post-processor wizard, all with ‘next’ prompts. And new wizards can be built for repetitive tasks with a variety of variables.”

However smart today’s machines are, the CAM programs that drive them must be smarter. Mastercam, for instance, allows users to move a part from one machine to another of entirely different make. Although the two machines might do almost exactly the same thing, the small differences and idiosyncrasies between them can add up to the point where a part might be damaged after a change of machines. Mastercam can figure out what those differences are and change the tool paths accordingly.

“It’s definitely a mix of looking toward the future and looking practically at what people do now,” Mund said.

Some time in the future, be it distant or not, shops will have just one or two machines and they’ll be smart enough to report on the accuracy of their performance every step of the way. The smart machines of the future are to be self-correcting and self-calibrating—practically self-aware. But the ability of a machine to measure itself and then right itself is useless if it doesn’t know precisely when an adjustment is called for.

But there’s a basic problem with most machine tools. “How do you know if you’re out of whack if you don’t know what whack is?” asked John Callen, vice president of marketing at Gibbs. With the way machines and CAM now interact there would be a danger of a “tolerance stacking problem.” If a machine tool has an idea of how sloppy it can be, and it tries to read an algorithm from a CAM program that has a tolerance notion associated with it, the machine is likely to become very confused as to how much deviance it’s allowed. “You have to revamp the code in the first place. You have to look upstream—as far upstream as you can go,” Callen said.

As more and more machines come out that require fewer setups, cut production time, and perform more tasks, it’s the job of the CAM software manufacturer to keep pace and let the end user do all these things with ease. “If the CAM doesn’t support the capability, you can have the best machine in the world and it’s not going to produce,” said Smiths Aerospace’s Bob Curwood. “It’s like having a car. If you can’t put gas in it, it isn’t going to go anywhere.” Any mini-revolution in machining will require a similar minirevolution in the programs that drive them.

Copyright © 2006 by ASME
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