When manufacturing monolithic structural parts for commercial and military aircraft, few machines are big enough for the job. That’s why management at Triumph Structures – Wichita invested in a Makino A6 – the first one installed in the U.S. In production since mid-2016, this 5-axis horizontal machining center (HMC) has exceeded its goals:
- Lowered cycle times by more than 50% for aluminum parts previously processed on a gantry-style vertical machining center
- Reduced part changeover and setup times through use of dual automatic pallet changers – from hours to minutes on some applications
- Increased peak metal removal more than 6x (525%) from 80in3/min to more than 500in3/min
“We strive to be a world-class facility. We want to not only deliver on time with good quality, but we also intend to be world class through our processes and the way we cut aerospace structural parts. To do that, we obviously need to have world-class equipment to support that dream,” says Kelly Eilerts, applications manager for Triumph Structures – Wichita.
Big parts, big challenges
Triumph Structures – Wichita is a division of Triumph Group, a global leader in manufacturing and overhauling aerospace structures, systems, and components. In Wichita, Kansas, machinists make a variety of jet aircraft and helicopter parts, which are then transported to other Triumph facilities for subassembly before delivery to original equipment manufacturers (OEMs).
Making complex aerospace parts out of titanium and aluminum – some billets start out as large as 3,000 lb and 17ft long – the company continues to invest with Makino. By the middle of 2017, there will be 18 Makino machines including the A6; three T2, 5-axis HMCs for landing-gear trunnions and other hard metal parts; and 14 MAG3, 5-axis HMCs for high-productivity machining of aluminum aerospace parts.
The T2 machines enable machinists to cut titanium and steel parts at a feed rate of up to 630ipm. They can efficiently mill titanium because of several advanced technologies including an active damping system; rigid construction for enhanced performance; a high-torque, high-powered spindle; and a high-pressure, high- volume coolant system for increased speed and productivity. A third T2 is being relocated from another Triumph location to expand the company’s titanium capabilities in Wichita.
The 14 MAG3 HMCs, including standard and MAG3.EX versions, run at 33,000rpm to machine wing ribs, wing spars, bulkheads, floor panels, and stringers. There are also plans for an additional five MAG3s to be moved from another location and installed within a Makino MMC2 pallet-handling system to create a cell dedicated to wing ribs.
“With the combination of the MMC2 and MAG3 machines, we’re able to run large aluminum parts 24/7 with an overall equipment effectiveness (OEE) of 85%,” Eilerts says.
For the largest wing skins, spars, and ribs, however, the company’s gantry-style vertical mill wasn’t up to the task. While capable of producing parts that meet OEM requirements, the machine limited the company’s ability to grow with the aerospace industry. Specifically, Triumph needed better thermal stabilization to improve precision. Four walls enclose the gantry-style machine, but it doesn’t have a roof on the cabinet or climate controls – exposing the spindle, tools, and workpieces to temperature changes in the shop. With programs scaled to account for temperature variation, the process is slow and operators must take multiple temperature readings before, during, and after processing.
In addition, the gantry-style machine has no external workstation for setting up pallets or means of changing tools automatically. The spindle must be stopped each time a tool is replaced or parts are loaded and unloaded, increasing unproductive time.
What’s behind all that power
While parts can be accurately produced on the gantry-style machine, it requires more time than a high-speed HMC such as the A6. The vertical spindle on the gantry-style machine turns at 25,000rpm, powered by 80hp while the A6 is equipped with a 33,000rpm horizontal spindle, powered by 161hp.
“This speed and power upgrade enables Triumph’s operators to hog out metal on the structural parts in some cases as fast as 1,600ipm,” says Ricky Davis, director of operations at Triumph and a veteran of nearly 30 years at aerospace manufacturers in the Wichita area. “I’ve never seen a machine move that fast.”
To control thermal variation, which can affect tolerances, the A6 is equipped with its own heating, ventilation, and air conditioning (HVAC) system that pumps 45 tons of chilled air into the machine enclosure to keep the work envelope, bed casting, and automatic tool changer at 68°F. Coolant is automatically chilled or heated as needed to maintain a constant temperature in the spindle, tooling, and workpieces.
“The gantry machine is much larger, but the temperature taken at the beginning of machining is not going to be the same as the temperature taken at the end of machining. That can introduce a lot of variables. Heat from the machine itself is added as it’s moving. Coolant temperature changes. This affects the temperature of your part,” Eilert explains. “With the A6, these variables have been removed. That makes it much easier for us to machine large parts accurately and consistently without having to scale our programs,” Eilerts states.
What really influenced Triumph’s decision to invest in the A6 was to improve productivity.
Equipped with two work tables outside the machine, design of the A6 enables operators to set up pallets with any combination of jobs – presently it includes four versions of wing skins and spars for those wings, a wing rib, and three versions of helicopter floor panels. Ergonomic worktables are lowered into a horizontal position so operators can safely and comfortably bolt and pin workpieces into position. Once setup is complete, the worktable is raised into a vertical position and is ready to be moved into the A6, just as soon as processing of another part finishes.
Triumph takes full advantage of this capability. The company runs two, 12-hour shifts on weekdays, with one operator scheduled on the A6 during each shift. Before weekend shifts, jobs are set up in advance and ready to be run by an operator who splits time on other machines on Saturdays and Sundays.
“That’s where the multiple tables come in handy, because we are able to use our limited resources on a weekend to unload and reload a part while the machine is still running,” says Nick Raffety, the lead A6 operator.
Equipped with an advanced Makino control, the A6 also can be programmed to automatically shuttle loaded pallets in and out of the machine, freeing up operators to handle other tasks. Triumph also equipped the A6 with Makino’s MPmax software to monitor the machine’s performance, including what programs it ran, cycle times, tool-change times, and utilization rates. MPmax can alert operators and managers to issues or when it’s time for a part change. This is just one way in the team is continually learning and implementing new features to expand unattended operations.
High speed, high quality
Because of speed, precision, repeatability, and high quality, the A6 enables Triumph to expand its relationships with customers and to pursue new customers. The A6 also keeps Triumph Structures – Wichita right where its leaders want to be – on the cutting edge of manufacturing technology and learning new ways to make better aerospace structural parts for less cost.
“We’re still proving out our processes and parts, but we have a lot of parts we could run on the A6 and reduce our cycle times by 40% to 50%,” Davis says. “We’re just getting started.”
Triumph is now planning their next step with Makino.
Triumph Structures – Wichita