March 2012 / Volume 64 / Issue 3|
By CTE Staff
Relying on a workhorse machine tool with a CNC that functions more like a wounded pony is not a plan for optimal production. Helac Corp., Enumclaw, Wash., dealt with that scenario on its 1998 Giddings & Lewis-brand vertical turning center from MAG IAS LLC, Erlanger, Ky. “It never did work right,” said Jerry Gilara, director of continuous improvement, about the factory-installed CNC. “It was a beast for us and the only weird one we had in the shop.” He noted that, for example, the control had to be programmed using a radius instead of a diameter.
In addition, the machine had DC axis servodrives and servomotors, which are more maintenance intensive and harder to get parts for than AC ones. “The VTC is a rock-solid, very capable machine, but its older CNC and DC drives/motors were an Achilles’ heel,” Gilara said.
Helac’s main product line is helical hydraulic rotary actuators, which translate linear piston movement into rotary motion and produce high torque with high load-bearing capacity. They are used as positioning and steering components for mobile construction, agricultural and marine equipment.
According to Gilara, a significant percentage of the company’s parts, which typically weigh 60 to 500 lbs., are machined on the 36 ", fixed-height, 2-axis VTC. For example, the machine roughs drawn-over-mandrel, tube-shaped actuator housings, utilizing a 3-pallet pool of queued work to maintain production during the machine shop’s 80-plus-hour workweek.
The tube-style parts have welded steel flanges on each end and some have off-center plates on the sides. “We mount these on an angle plate that has half-rounds to locate off the tube OD,” Gilara said. “We bore the part completely in one shot from the top, with tolerances of 0.001 ". Then we face two parallel surfaces so everything is concentric. We do all the machining from one end, using a 250-lb. boring bar with a CAT 60 taper.”
Being able to handle heavy tools with long reaches in an automatic toolchanger was one of the main reasons Helac purchased the VTC, Gilara noted. “We wanted to be able to do everything from one side instead of flipping the part.”
He added that the shop has an older CNC lathe that once machined the parts the VTC produces and serves as a slower, backup machine. “Another reason I bought this machine is because I got tired of that backup machine,” Gilara said. “When our primary machine is down, we’re quite unhappy.”
Rather than investing in a new machine tool, Helac decided to have the VTC retrofitted, including installation of a new Fanuc 0iTD CNC, AC spindle and AC digital-axis servodrives and servomotors. The shop requested quotes from a number of retrofitters and decided to go with the company that built the machine even though the other quotes were considerably less. “I did not want to have some dirt-cheap deal and try to make it work and have the machine sit there for 2 months,” Gilara said.
All images courtesy of Helac
The retrofit also included a health check of the machine tool to ensure its accuracy.
MAG uses pre-engineered, modular retrofit packages with prebuilt panels. The modular approach allows retrofitting just the CNC or the CNC, drives and motors at different times, if needed, to accommodate tight budgets.
“We did it during our slower season, and we struggled while it was down,” Gilara said. “The VTC is a prime piece of equipment for us.”
Although Helac is not standardized on Fanuc controls, the similarity of the 0iTD CNC to others in the shop enables quicker programming and easier training. “Operators familiar with other machines in our plant can migrate to this machine with less training,” Gilara said. “You almost had to talk to that special control, bring it a cup of coffee and pat it on the butt to make sure it worked OK. Now we don’t have to do that.”
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