CNC Machines Go Horizontal
This article first appeared in IMPO's July 2013 issue.
Suburban Manufacturing has been in business more than 33 years and has a gleaming, state-of-the-art 30,000 square foot CNC machine shop. Their 65 employees – many of them tenured machinists – are innovative, creative, and motivated. At Suburban, the employees are given fertile ground to think, innovate, and redesign processes, fixturing, tooling, setups, and much more. According to president and company founder Rick Grice, the essential ingredients in keeping Suburban successful and competitive are their innovative people and the fact that the company is employee-owned.
According to vice president Brian Nuibe, Suburban is a “true job shop. We have vertical machining centers and horizontal machining centers, single- and multi-spindle CNC lathe machines, saws, hones, sand blasting, part marking — a huge array of operations,” he says. “We run all grades of aluminum, stainless, brass, hastaloy, Inconnel, and titanium. We run bar, plate, castings, forgings, and extrusions. We tackle a mixture of prismatic and cylindrical parts. We do everything from prototyping to production and everything in between.”
So when Suburban went shopping for new horizontal machining centers to add to their CNC machine arsenal, the candidate had to be able to handle all of the above, plus deliver aerospace machining tolerances and finishes, be lightning fast, precise, and rigid. They settled on two new Okuma MB-4000H horizontal machining centers and a larger PALLETACE flexible manufacturing system. This decision was based on previous experience with Okuma’s MA-500 horizontal machining centers and Fastems FMS, which were originally purchased after the 2008 IMTS.
Reasons for selecting Okuma over other brands included Okuma’s solid reputation, the fact that the company has a long history (since 1898); Okuma’s distributor, Gosiger (Cleveland), was well known for its solid service and support; plus Suburban had previous experience with Okuma. “We have an Okuma MC 50 horizontal machining center with a 50-tool ATC, CAT 50 taper tooling, 50 hp motor, and multiple pallets,” Grice says. “We call it the Green Monster. This CNC machine is over 25 years old, and it’s still running today, holding great tolerances and can still really take a cut.”
Gosiger’s service has been an important part of the process of bringing in the new machines, according to Grice. “The Gosiger training is great. They go to great lengths to fully understand the CNC machines, and to make sure we do too.”
When the original Okuma MA-500 arrived, it was shortly followed by a Fastems pallet storage/management system. Once the two were tied together, four 20x20-inch pallets from the older MC-50 were moved over to the MA-500. Just by moving from the old to the new, cycle time was cut by 20 minutes and this without making any other changes. The difference was speed. The MA-500 has a rapid traverse of 2,362 ipm with a 0.7 G acc/dec — far faster than Suburban’s other horizontal machining centers. “What we’re doing is taking very tall tombstone fixtures and loading them up with parts. The tombstones are eight-sided and stacked two high, one atop the other. This way we can get as many parts as possible on the table at one time,” Nuibe says.
“We moved a job that ran on one of our vertical machining centers. The job was fixtured with four vises,” Nuibe says, “and we put it on one of the Okumas. We can now run 12 parts at a time — and run lights out. We were so pleased with the original system that we’ve purchased two MB-4000H horizontal machining centers with a 3 tier, 36-pallet Okuma PALLETACE system. It’s still being installed but will eventually replace a couple of machines, including an old vertical machining center.”
Nuibe says that Suburban is leaning more and more on horizontal machining centers because with the pallet changer one can almost eliminate idle spindle time. The spindle is turning even during pallet changes. “We put a fixture in, and we do all the loading and unloading outside the machine, while the machine is running,” he says. “Further we’re trying to combine operations at every turn. With the vertical machining centers and lathe machines, we may have to do three to four setups. With the horizontal machining center, we do a single setup, saving all that setup time.”
Not only is time saved with single setups, but costly setup “variables” are eliminated as well. Every time an operator touches a part, fixturing and refixturing the setup, this introduces the possibility (and likelihood) of process variability, which may result in out-of-spec parts requiring time-consuming rework and/or scrap. The fewer variables in the process, the greater the odds of first part/good part.
“These CNC machines are very productive, and we’re getting outstanding uptime,” Nuibe continues. “They’ve conquered everything we’ve put on the table. Our impression of Okuma at the time of purchase was very good, and that hasn’t changed a bit. These are the perfect CNC machines for what we want to do now and what we’re planning for in the future. Customers come through here and stop dead in their tracks when they see the horizontal machining centers and FMS systems. They’re just wowed.”
Nuibe sums up his experience with a simple statement: “Okuma machines do what they say they’re going to do.”
The ultimate goal, according to Grice, was to replace some of Suburban’s older equipment, machines just not holding repeatable tolerances. They are retiring some of their vertical machining centers. “Each of those machines requires a dedicated operator, and if we just move the work over to the horizontals, it frees up people to work in other parts of the shop and opens up valuable real estate. This is a gradual process, but Okuma is helping speed up the process.