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Small Systems Help to Keep Big Jets Flying

March 1, 2012
A specialty manufacturer of hydraulics components plays its part in multiple aircraft programs
The Boeing 787 “Dreamliner” has more Triumph Actuation Systems products installed than any other commercial aircraft in production.
A rotor during the grinding process on the S33 at Triumph Actuation Systems.
A rotor, fixtured and awaiting the start of the grinding process.
A piston rod set-up.
A set-up on the Studer S20 ID/OD grinder.
A piston being ground on the S33.
G.William Burke III (left) and Brent Holder, operator. Triumph Actuation Systems’ Studer S20 is seen in the background.

When you think about Boeing’s new “Dreamliner” 787, what comes to mind? Its remarkable size (wing span: 197 ft; length, 186 ft; height, 56 ft)? Or, perhaps it’s the 787’s astonishing cruise speed of Mach 0.85? All awesome stats, but probably you don’t think hydraulic systems, linear hydraulic actuators, rotary pumps and motors — the largely unseen yet indispensable systems and assemblies that keep the flight experience uneventful

Triumph Actuations Systems opened its Clemmons, S.C., plant in 1989. It’s 130,000 sq. ft and employs 230. Its main product lines are linear hydraulic actuators, solenoid and manually operated hydraulic valves, hydraulic systems, rotary pumps and motors, and variable and fixed displacement axial piston pumps and motors. Triumph’s customers? Just about everyone in commercial and military aircraft (Boeing, Airbus, Grumman, Bell, Sikorsky, Piper, etc.).

“When I joined Triumph,” said William Burke, CNC programmer/manufacturing engineer, “we were all about hydraulic systems and linear hydraulic actuators, rotary pumps and motors. Then we acquired the Honeywell line — more, and completely different, hydraulic pumps and motors. This was entirely new work for us and required a learning curve, an increase in capacity and technology, and investment in additional personnel to retain the balance between our traditional actuation systems and the newly acquired hydraulic pumps and motors.

“At that time (1990s) our customers were about 80% commercial aircraft builders and 20% military,” he pointed out. “When the original company started (1942) the mix was 80% military and 20% commercial. Today, we’re about 50% commercial and 50% military.”

Examples of Triumph’s linear systems can be found on the Boeing 737 (and much of the rest of the Boeing fleet), such as the actuators for the cowl or nacelle. These open and close the doors for access to the engine compartment. These actuators have a cylinder, a hydraulic reservoir and body with a piston that extends and locks. They also have a bearing at one end so the system can pivot as it extends.

There are similar systems for opening and closing cargo doors. Think of the huge C17 and C130 cargo planes with the very large, heavy rear cargo doors. Triumph makes the actuation systems that open and close those doors, and locks them, too.

There are also actuation systems that operate the nose gear and landing gear — opening and closing the nose gear and the landing gear doors while lowering and raising the actual nose gear and landing gear. Triumph builds these systems, supplies them to Boeing, and Boeing puts the systems on the actual landing gear assemblies.

“Some of these parts are for the B-1 Bomber,” Burke said, “while on the other end of the spectrum, we do a lot of work with Piper, smaller parts by scale. We also do some helicopter work for Bell, and we make several systems for the V-22 Osprey. The new 787 ‘Dreamliner’ is the one plane that singularly has more Triumph components and systems than any other aircraft, period. The cowl door actuators, pull in actuators that lock some of the doors, landing gear systems, and so on.”

U.S. sourcing
“We do about 10% of our manufacturing in house. The rest is outsourced to companies in the U.S.,” Burke said. “We have in house NDT (non-destructive testing), highly sophisticated quality departments and, of course, extensive testing. We test every actuator and pump and motor. These have rigorous test requirements that are far beyond the system’s normal life expectancy. We test the extension of the hydraulic actuators, the locking mechanisms, the releases. We do leak tests, vibration tests; we’ll check wear patterns to see if there is a possibility of materials breaking down. Our tests are very extensive.

“We work very closely with our customers to achieve Design for Manufacturability (DFM),” he continued. “Considering what the customer wants, our design team will create the design and then review it with the customer, with a critical eye on DFM. The design of the pump or linear actuator has to work, obviously, but we look closer, at better ways of making it, different materials. Are we using the most efficient, cost-effective design and processes? These are essential criteria for coming up with the best solution, for us and for our customer.

“We regularly audit our suppliers to see if we can possibly bring a particular supplier’s product directly into our stock system — without doing incoming inspection,” Burke said. “This requires of them complete traceability: all operations performed, equipment used, tolerances and surface finishes held, inspection and verification systems used, any process variations and so on.”

Burke explained that many of their products are sent out for anodizing or plating (chrome, cad, or nickel.) However, before these parts are sent out, they undergo considerable prep work — turning, horizontal and vertical milling — so the part comes off these processes nearly complete. He also indicated that at the Clemmons plant Triumph performs considerable internal and external (ID/ OD) grinding steps, as well as some internal honing, lapping and other secondary operations.

Grinding — “The typical parts that we do here include shafts, piston rods, rotors for our hydraulic pumps, housings, bearing journals, piston-and-sleeve match grinding and some seat grinding,” Burke detailed. “Tolerances are ±50 millionths, and 2-16 micron surface finishes are the norm. Tolerances like these require digital mics on the ODs, electronic gauging and air gages for any precision ID work.”

The diameters that Triumph grinds range from 0.125 in. up to 4 in., and lengths range from 0.250 in. to 13 in. One of the largest rotors it produces has a length of 7 in. They may only grind several areas on the rotor instead of the entire rotor. Many times, according to Burke, they’ll grind multiple diameters and shoulders in one operation.

“Our biggest bearing journal is 3 in. in diameter,” Burke said. “We may grind the body of the rotor, the bearing journal of the rotor, or an area for fixturing. We put our own forms and radii on our wheels for parts that require plunge grinding. We do an angular plunge so we can grind the shoulder and the diameter at the same time. We’ll bring the wheel in at an angle, plunge, and then traverse to get the finish that we require.”

Cycle times range from 2 min to 5 min per part. Triumph doesn’t do any high-volume grinding. Most of the jobs are in 24 or 30 part lots. Changeover times are from 30 to 90 min, part-to-part, with each part a different configuration. For parts within a family, changeover is just a matter of minutes.

“Most of our ground parts,” Burke continued, “like rotor shafts, will run between centers, with a dead center, or a live center to support the shaft, and we’ll drive the shaft and grind the OD. We also have specific fixturing for part locating, and we will also grind parts, holding them in a collet in the grinder.”

Burke added that a particularly long shaft (a 7 in. rotor shaft) would be going into one of Triumph’s rotary pumps and motors. These are hydraulic systems that serve the auxiliary power units when the plane is on the ground. Sometimes, when you’re waiting on the tarmac, you may hear a voomph, voomph, voomph right under your feet: that’s a Triumph pump working the hydraulic systems.

Materials — “We grind a large range of materials and multiple material types,” Burke said, listing 4340 steel, 5-15 PH stainless, and 7075 aluminum. “We’re pretty heavily into aluminum parts, and consequently we do considerable aluminum grinding. Some of our other materials include bronze, and a material called Toughmet 3, which is a spinodal bronze. It machines like the 4340 but has greater wear-resistance and toughness.

“Most of our rotors start out as 4340 steel, and we have our own internal bonding process where we’ll put high-leaded bronze plugs into our rotors, and we’ll diffusion bond those together at high temperatures in a furnace. Then, when the rotor comes out of the furnace, we’ll start machining the bonded features, revealing those bronze plugs. These are usually wear areas where our pistons run inside the cylinder. It looks like the cylinder for a pistol revolver, except it has bronze plugs in the ID and we ream that out, leaving a small bronze wall thickness in the piston bore. The bronze helps to lubricate free piston movement, along with the hydraulic fluid the piston is pushing in and out.”

The old grind, and the new one
“Many of our parts come from the lathes or mills,” Burke said, “and we’ll grind specific ODs for a bearing journal for fixturing, as well as final print dimensions and, when necessary, some ID grinding. Our newest Studer S33 from United Grinding Technologies is an OD grinder. However, we still have a Studer S20 that’s both an ID and OD grinder. Our aluminum parts come from machining and go immediately outside for processing, like anodizing. The parts come back to the grinding department, and we’ll grind the anodizing off certain areas of the OD. Very often it’s necessary to do this, especially in a bearing area. Then, we’ll send the part out for hard coating. By exposing the aluminum after anodizing, the hard coat will only attach to the portion of the part that was ground. Often we’ll have them build up the coating larger than we need, and then we’ll grind the hard coat to size, not taking the coating below the parent aluminum.

“Selecting the Studer S33 required extensive research, and I admit that brand-recognition played a part, because we already had the S35 and the S120. Nevertheless, and we did an extensive study, looked at a number of machines from different manufacturers. In the end, we chose the Studer S33 over the other manufacturers’ machines because of its ability to meet our specific and unique grinding needs. Given our extensive experience with the Studer S35, we were certain the Studer S33 would perform the grinding of our parts — as well as open Triumph to future part applications. In that sense, the purchase of the Studer S33 was partly a replacement of older technology, and partly an opportunity to expand Triumph’s reach into more and different applications. Plus, the Studer S33 was almost an immediate transition from the Studer S35.

“One big advantage has been that with our older machine, we could only program one part at a time — you had to blow the program out after every job, so we were writing a new program every time. The Studer S33 allows us to write programs, store them in the control, and upload and download them to our system. The operator now just has to call the program up, set his grinding limits, push the button, and go. It’s very user friendly; the Windows-based StuderWin software is very powerful, and easy to use. I write all the programs for the Studer S33, and our operator does the set-up and grinds the parts. We’ve really worked together well on it and built a very large inventory of programs. When parts come back to our grinding department, unless it’s a new part, we’re off and grinding in a very short time.”

The Studer S33 allows Triumph to bring more new work into the shop because the changeovers are faster, Burke added. “We can grind more features in one set-up. We’ve brought many new jobs in since we’ve had the S33, and it’s been an extremely smooth transition. Some of these are actuator parts or pumps or motors; sometimes they’re piston rods, where we’ll grind the body and the head, and various features.”

“Everything has just gone flawlessly,” said Burke. “I’ve assisted in acquiring two other machines and have brought the last two pieces of equipment in here. We’re about ready to bring in four more, one of which is going to be an ID grinder. I’m strongly considering Studer to replace an older, manual machine.

“We have a very good relationship with UGT, especially with Bob Beals,” he said, referring to the UGT sales rep. Burke also credited UGT service engineer Ray Wyland and applications engineer Jim Lennon. “I can’t say enough about them and their response to come and help us. Plus, UGT has helped by making wheel suggestions, has put us onto different wheel manufacturers, and they’ve been in here helping with our applications.

“I guess what I’ve learned through this process is the importance of selecting not only the latest and best technology — you’ve got to do that to stay ahead of the competition,” Burke concluded, “but also to acquire that technology through a great partner.”

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