New CNC and AC servos revitalizes 12-year-old VTC
Most shops take for granted the quality and reliability of their electric power, though some regions have inescapable power fluctuations and outages. Operating CNC machine tools in an area like this spotlights how well a machine control handles a power hiccup: can the CNC recover quickly or does it forget what planet it’s on?
Jerry Gilara, director of Continuous Improvement, and his maintenance team at Helac Corp. in Enumclaw, WA, knew the answer for an older workhorse vertical turning centre the company relied on. Built in 1998, the MAG VTC, critical to the company’s production, experienced significant downtime with every power hiccup.
“This is a rock-solid, very capable machine, but its older CNC and DC drives/motors were an Achilles heel,” says Gilara. “We’ve always been pleased with the machine, so we had MAG retrofit a new Fanuc CNC and AC digital axis drives/motors and spindle. The retrofit transformed the machine, making it utterly reliable and giving us other advantages because of the widespread use of Fanuc controls in our shop.”
Helac’s main product line is helical hydraulic rotary actuators, a clever device that translates linear piston movement into rotary motion. Extremely compact, the Helac actuator produces high torque with high load bearing capacity, making it ideal as a positioner or steering component for mobile construction equipment, forklifts, aerial platforms, utility vehicles, agricultural equipment, and marine applications. The actuators provide swing, steering, head rotation, articulation and similar capabilities, with drift-free, brakeless positioning, and protection from overload conditions. The device is covered by many patents and has been adapted and sized for numerous applications.
Gilara says a significant percentage of Helac’s parts pass across the MAG VTC, a 36-in., fixed-height, two axis machine. The machine does heavy metal removal on the tube-shaped housings used for many actuator models, utilizing a three-pallet pool of queued work to stay in production during much of the plant’s 80-plus hour workweek. Several hundred different part numbers are involved, made of DOM tubing and alloy steel, weighing 60 to 500 lb. The tube style parts have welded steel flanges on each end and some have off-centre plates on the sides. “We mount these on an angle plate that has half-rounds to locate off the OD of the tube,” explains Gilara. “We bore the part completely in one shot from the top, with tolerances of 0.001 in. 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, which is a primary reason we purchased this machine. We have a backup machine for this work, but that machine is what caused us to purchase the MAG unit. When our primary machine is down, we’re quite unhappy, because parts aren’t moving through production.”
With power quality often in question due to wind conditions in this region of Washington, the machine’s control often lost its memory during brief power outages. “Every time the power hiccupped, the control would lose memory, even with an outage of just a minute, and it could take a day or two to reload all the programs,” says Gilara. “If it happened on second shift when no maintenance people were available, the machine might sit idle until morning before someone could work on it. The CNC hardware and DC drives had become liabilities, too.”
Helac discussed a retrofit of the CNC and drives/motors with MAG in 2009, and the new hardware—a Fanuc 0iTD CNC, AC spindle, servo drives and motors—was installed in 2010. MAG uses pre-engineered, modular retrofit packages with pre-built panels. This modular approach allows economical retrofit of just the CNC, or the CNC with servos, spindle drive and motors—at different times, if needed, to spread out the budgeting.
“Our power quality issues have become non-issues since the retrofit,” says Gilara. “We went through an entire winter without a problem. And, the similarity of the Fanuc control to others in our shop has given us advantages in programming and training. We can now post process to a Fanuc file, like the rest of the machines in our plant, and operators familiar with other machines in our plant can migrate to this machine with less training. The faster data handling of the new control also yields improvements in finish. Given this machine’s workhorse capability, accuracy and repeatability, the retrofit has proved a cost-effective investment.”