April 2012 / Volume 64 / Issue 4|
Part makers get a better angle for multiple-axis work
By Kip Hanson
| Swiss-style machine tool builders give part manufacturers a better angle for multiple-axis work.
Say your machine shop just received an order for 316 stainless fuel-injector nozzles requiring angled holes to be drilled on the workpiece face. Or perhaps your best medical customer needs miniature blood-pump impellers with complex 3-D blade geometries like those on a jet-engine turbine. How are you going to make them?
Conventional wisdom says do as much as possible on a Swiss-style machine, then chuck them up one at a time on a tilt-rotary table and tie up a $100,000 machining center just to whittle away a thimbleful of material. And then the deburring remains, which is not only time-consuming but, if done improperly, degrades part quality. There has to be a better way.Big Step Forward
You might perform some of this work with fixed-angle drilling attachments, but these are limited. Brian Such, Elk Grove Village, Ill.-based customer support group manager for Marubeni Citizen-Cincom Inc., Allendale, N.J., explained that drilling any hole requires two angle attachments—one for the center drill and another for the drill itself—each costing upwards of $10,000. If you have two different angled holes to drill, you’ll spend $40,000 and burn up four stations. And contouring work? Forget it, because only a programmable B-axis will do.
Courtesy of Eurotech
A B-axis? Why would a Swiss-style machine—already crammed with dozens of tools and enough axis letters to score big in Scrabble—need even more complexity? The answer is simple. On any machine tool, eliminating secondary operations saves time and improves part quality—Swiss-style machines are no exception.
A programmable B-axis means you aren’t hindered by fixed-angle tool attachments. Instead of losing an entire station to a single operation—drilling an angled hole or milling a 45° angle—Swiss machine shops can drill or mill at any angle until the cows come home, often while using the same cutting tool to machine multiple features, which is impossible with a fixed-angle attachment. The ability to do multiple-angle interpolation similar to a 5-axis machining center is also a major advantage.
It’s for these reasons that Swiss-style machine tool builders offer B-axis machines. For example, Citizen’s M432 VIII is a gang/turret machine, meaning it carries both gang-style tool posts as well as a live-tool-capable lower turret. Citizen has also equipped the machine with a B-axis tool post in the upper part of the work area, on which are mounted three rotary tools capable of multiaxis contouring through 105°.
Only three tools? “Some builders put the B-axis on the turret and add a toolchanger,” Such said. “Sure, you can get more tools that way, but it’s also more expensive to build and slower.”
According to Such, Citizen performed market surveys and found that three is the magic number when it comes to B-axis rotary tools for most Swiss operations. “We elected to do three tools on the slide based on what our customers were asking for.”
Courtesy of Marubeni Citizen-Cincom
Courtesy of Eurotech
Such noted that most customers use the B-axis option more for multiple-angle drilling than for complex surfacing. One example is a hydraulic component. What previously took 85 seconds to produce on the customer’s old Swiss-style machine takes 57 seconds on the M432 VIII, with no change to feeds and speeds. “By having the B-axis on the gang slide, it allows the turret to do additional work while the slide is busy drilling the holes,” he said.
One of the biggest benefits to a B-axis Swiss-style machine, according to Such, is reduced setup time. “Not only are you setting up fewer tools, you also avoid mounting one or more fixed-angle attachments and touching off tools sitting at various angles,” he said. “And with the Cincom controller, all you have to do is set the tool in the Z-axis, program the correct angle and go.”
The controller is a key part of the B-axis puzzle. According to Such, most B-axis controls can be difficult to operate and program, so Citizen simplified its control. It partnered with Mitsubishi to develop proprietary, easy-to-use software based on the 700 series Mitsubishi control. “We didn’t just bolt another axis motor on the machine. The B-axis is completely integrated into the machine.”
As proof, Such offers a hypothetical situation: the middle of a B-axis drilling operation where the tool is buried in the workpiece at 30°. “You could shut the machine off in the middle of the cut, power it back up, go to jog mode for that tool and crank it out with the handwheel. The machine will move the tool at the correct angle. Try that with any other machine and you can kiss that tool goodbye.”
The Citizen B-axis option typically costs $15,000 to $20,000 on a Swiss-style machine that costs $460,000.Get off the Slide
German machine tool builder INDEX TRAUB Drehmaschinen GmbH & Co. KG has come up with a different way to build the B-axis. Tyler Economan, proposal engineering manager at INDEX Corp., Noblesville, Ind., described the design of the company’s Model TNL 18-7B automatic Swiss-style production lathe as one equipped with a pivoting upper turret capable of performing main or sub spindle machining, eight tool positions carrying up to 24 tools, and programmable B-axis rotation up to 100°.
Courtesy of PartMaker
“This machine was introduced at EMO and is new to the U.S. market, and we’re finding it’s an ideal fit for users who have complex parts made from difficult-to-machine materials,” Economan said. “To achieve these geometries before, you had to use form cutters or angled heads. Now you can simply adjust the B-axis to whatever angle is required and machine with the same rigidity and benefits as you would on a vertical machining center.”
TRAUB may take a different design approach than Citizen and other Swiss-style machine builders, but that doesn’t make its machine easier on the pocketbook. Economan justified the “more than a Cadillac” expense of its equipment by emphasizing the machine’s ability to reduce cycle times and increase flexibility. “You can improve your return on machine investment,” he said. “In some instances, we have demonstrated that even a 20 percent increase in productivity easily justifies a 40 percent increase in machine price.”New Kids on the Block
The B-axis option is also not new for Japanese machine tool builder Tsugami Corp. It introduced the TMU1 more than 9 years ago, and it is geared toward turning complex, multiaxis medical and aerospace parts using a 16-tool turret and a B-axis live-tool spindle serviced by a 60-tool automatic toolchanger.
Courtesy of INDEX TRAUB
Ron Gainer, Swiss product manager for Rem Sales LLC, Windsor, Conn., exclusive U.S. distributor for Tsugami, explained that its new SS207 B-axis Swiss-style machine was introduced last year. He said: “The SS207 is a 20mm machine with three rotary tools mounted on the programmable tool post for use on the main spindle, and three for the subspindle. With full B-axis capability on a lower- cost, gang-style Swiss machine, you can often avoid having to purchase a more complex machine with a toolchanger. It’s basically for any shop that makes a lot of angular holes or does multiaxis contouring work.”
Gainer added that, before the SS207, attachments were required to make angular holes on Tsugami gang-style Swiss machines. “Now it’s just program the code and go,” he said. “Shops are making small, complex medical parts that require B-axis operations, including contouring, rigid tapping and even thread milling and whirling. And shops are always looking for ways to reduce setup time.”
Courtesy of Eurotech
The SS207 with B-axis capability costs about 15 percent more than a comparable Swiss-style machine without a B-axis.
Another B-axis Swiss-style machine offering is from Po Ly Gim Machinery Co. Ltd., Taiwan, which is distributed in the U.S. by Brooksville, Fla.-based Eurotech Inc. Jeff Walz, president of Eurotech, said Po Ly Gim has been building gang-style B-axis Swiss-style machines for more than 10 years, but they were not imported until recently.
“The B-axis is a compelling feature,” he said. “It gives you a lot more flexibility with angled holes, but, more than that, it allows you to basically double your live-tool capacity, in that the B-axis can swing around and do axial or radial work in addition to its regular job. We’ve also seen customers use the B-axis to reach inside a cross-hole and deburr the intersection. There’s always a push to drop the part off complete.” CTEAbout the Author: Kip Hanson is contributing editor for Cutting Tool Engineering. Contact him at (520) 548-7328 or firstname.lastname@example.org.
Are shops making a beeline to B-axis machines?
Choreographing tool movements
programmer’s will say when he sees a B-axis Swiss-style machine rolling through the loading door is, “You want me to program how many axes?”
U.K.-based CAD/CAM developer Delcam PLC has been in the software business since 1991, and Hanan Fishman, president of Delcam’s PartMaker Inc., Fort Washington, Pa., noted that Swiss-style B-axis programming has been a strategic part of the company’s development over the past 12 months.
He said: “The B-axis Swiss-style machines produce a lot of unique opportunities on myriad levels. The first is obviously the evolution of 5-axis machining—there are lots of parts that need this today, especially in aerospace and medical. Clearly, this type of work requires a CAM system.”
Fishman explained that there’s a big difference, however, between programming five axes for a machining center and programming five (or more) axes on a Swiss-style machine.
“It’s like the difference between figure skating and hockey,” he said. You can program a single tool on a vertical machining center and it is like Peggy Fleming, performing precise and complex maneuvers on the skating rink. If she falls—meaning the tool breaks—then you pick her up, dust her off (replace the tool) and start skating again. “It might hurt, but it’s not a big deal,” he said.
Now picture a hockey team, with all those players moving around. Their movements might not be as complex as those of a figure skater, but there’s still a lot going on at one time. This is like a Swiss-style machine, where you have tools flying around all over the place—bump a few of those skaters together and you’re going to have a lot of blood on the ice.
“The cost of collision is much higher,” Fishman said. “And by adding the B-axis to a Swiss machine, you’ve just put Peggy Fleming on the same ice as the Philadelphia Flyers. This is why you need a good CAM system, one with machine simulation, so you can avoid the crash before it happens.”
Despite this, according to Fishman, many shops still try to do programming by hand. “Our biggest competitor isn’t another CAM system—it’s the manual programmer,” he said. “Back in the day of long production runs, who cared if you took a few hours or even an entire day to program a job? But with decreasing lot sizes and increasing complexity, many shops are seeing one or more setups per shift, and more difficult ones at that. In this instance, it’s just not feasible to program manually, as it cuts into production time. Worse, you run a much greater risk of collision.”
B-axis programming, like CAD/CAM for milling, is “automating the impossible,” Fishman continued. “It’s simply not feasible without a system. But very often on a Swiss machine, at least on simpler work, it’s more a matter of automating the tedious and mundane. It can be done, but no matter how good of a manual programmer you are, the first time you get to see what that part looks like is after you’ve cut it on the machine. Not so with a good CAM system. The machine tool builder gives us Pinocchio. With PartMaker, we turn him into a real boy.”
Marubeni Citizen-Cincom Inc.
Rem Sales LLC
Swiss Automation Inc.
Swissline Precision Manufacturing Inc.
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