WWII Hydraulic Press Gets New Life

Universal Alloy Corporation (UAC), a business unit of Alu Menziken Aerospace Group of Switzerland and manufacturer of soft, hard, and metal matrix composite aluminum alloys, recently purchased and upgraded the world's largest indirect extrusion press to expand its aerospace market offering. Built in the 1940s in Germany, the 122-ft extrusion press was originally used in World War II. UAC purchased the press from Spectrulite Consortium, Inc. in St. Louis, MO, becoming its fourth owner. The press, which now extrudes 16,200 tons, was disassembled, shipped, and reassembled at UAC's Canton, GA facility where it began production in early 2005 after an extensive revamp effort by multiple vendors.

Hydraulic Overhaul

According to Paul Scaglione, UAC vice president of engineering, vendors were selected to redesign the massive extrusion press based on UAC concepts to convert the press from water to oil hydraulics and to add indirect extrusion capability. The Bosch Rexroth Hydraulics Systems and Engineering group in Bethlehem, PA provided the hydraulics package for the press, as well as the direct and indirect shears and two stretchers. The package included five hydraulic systems, piping and field startup assistance.

Scaglione explained that the hydraulics conversion was important to modernize the press to meet customer requirements for the next 20 years. "There were unique challenges in the conversion," says Scaglione. "We had to build the ‘Swiss army knife' that could run direct extrusions, indirect extrusions, and seamless hollows. We also had to be concerned with the large amount of hydraulic operation above and around the heated tooling at the front platen."

Originally, the 14,000 ton hydraulic horizontal three-stage extrusion press was used mainly to extrude magnesium and aluminum aircraft components. After WWII, the press was shipped from Germany to the United States as part of the U.S. Air Force heavy press program. The press was acquired by Dow Chemical Corporation and reassembled in Madison, IL where it was used to extrude magnesium alloys mainly for aircraft and missiles. Its third owner was Spectrulite Consortium, Inc., based in St. Louis, MO, which used the press to produce aluminum and magnesium extrusions. In 2003, UAC purchased the press rights from Spectrulite with the goal of expanding its aerospace business and increasing its competitiveness in the North American aerospace extrusion markets. In addition to the new press, the UAC facility in Canton operates four extrusion presses ranging from 900 tons to 2,750 tons.

The main pumps are Bosch Rexroth AAVSO500HS variable displacement servo-controlled pumps.

Bosch Rexroth learned of this project through a distributor, Hydraulic Controls Inc. "Bosch Rexroth was able to solve problems rapidly while under construction and their support team and start-up help that came out of Pennsylvania was excellent," says Scaglione.

Jim Lane and Otto Weber, systems engineers for Bosch Rexroth Hydraulics Systems and Engineering, worked closely with UAC to design multiple hydraulics systems for the massive press. The package included a 17,000 gallon hydraulic system – featuring a reservoir, pilot system, motor pump groups, and manifolds. The main pumps are Bosch Rexroth AAVSO500HS variable displacement servo-controlled pumps. The system also uses a Bosch Rexroth 4WRZE32 proportional directional control valve to control fast advance velocity of the press as well as a complete complement of the logic valve technology for system fluid management. Bosch Rexroth logic valve models include the LCT25 and LFT25, which are rated for operation at up to 14,500psi. The valves control the stripping function of the press up to 8,000psi.

According to Lane, billet and die handling on the press are aided by a 1,000 gallon water/glycol hydraulic system, which operates at 4,500psi on the hot side of the press. Weber noted the press was also outfitted with a new piping layout, using a weldless piping system. Piping sizes used in the new layout include up to 20" low-pressure piping and 4½" high-pressure piping. All piping and connections for the 8,000psi circuit were designed and tested specifically for the press application.

An 850-gallon hydraulic system with reservoir, motor pump groups, and manifolds were provided to drive the 1,500-ton stretcher used to further process the extrusions.

Additional systems in the extrusion press overhaul include a 60 gallon hydraulic power unit and manifold to control the clamping and feed of the large run-out saw used to cut extrusions coming off the press. Also, an 850 gallon hydraulic system with reservoir, motor pump groups, and manifolds was provided to drive the 1,500 ton stretcher used to further process the extrusions. A custom-designed pre-fill adapter was also added to allow mounting of the pre-fill valves in limited space and permit high-speed advance and return of the stretcher. Likewise, cylinders – specially designed to fit in the existing stretcher frame – were provided for the fast advance and return functions of the stretcher. Finally, rounding out the hydraulics package is a 1,200 gallon hydraulic system including, reservoir, pilot system, motor pump groups and manifolds to drive the press's 350-ton stretcher.

From a cost standpoint, UAC elected to reuse the original pre-fill surge tanks and pre-fill valves. The company also wanted to operate the press approximately 18 months from the purchase order date, so the goals were set very high for Bosch Rexroth. To help the transition, UAC hired the maintenance manager from the Spectrulite Consortium in St. Louis. "He relocated with the press, so he has the unique experience of seeing the before and the after," notes Scaglione. "In the first six months of operation, there have been no major leaks, no stuck valves, and no hydraulic problems of any sort. The most he's had to do is change a couple of O-rings. Bosch Rexroth exceeded all our expectations for the project.

"I knew Bosch Rexroth had the best big hydraulic pumps in the world, and I liked their capability for effective horsepower limiting. This allowed us to save money on transformers, switchgear, and future energy costs in the new plant," Scaglione adds. "I also felt that their systems and engineering group had the best experience with large hydraulic packages, not just with presses but with stretchers as well, which was important because we had a 1,500 ton and a 350 ton stretcher in the job that needed systems."

Above, – heavy press aerospace extrusions. The addition of the press expands UAC's aluminum extrusion offering from aircraft fuselage components to wing components including stringers, planks, and panels for military and commercial applications.

UAC's California plant has 11 presses serving the West Coast. By adding the converted extrusion press in Georgia, UAC now provides greater service to East Coast aerospace markets. The addition of the press expands UAC's aluminum extrusion offering from aircraft fuselage components to wing components including stringers, planks, and panels for military and commercial applications. "Currently, the extrusion press can produce a 32" billet in the direct mode and will operate billet to billet with maximum diameters up to 22" and up to 70" in length," details Lane.

All major aircraft manufacturers recognize UAC as a manufacturer of choice for aluminum extrusions. These manufacturers include the company's largest customer, Airbus, as well as Boeing, Cessna, Lockheed Martin, and their subcontractors. UAC operates a total of 15 presses from 170 tons to 4,800 tons with extrusions from 1/16" to 10" in circle size and maximum length of 42ft. Its operations primarily produce hard alloy aircraft fuselage extrusions up to 40ft in length and weighing up to 5 lb/ft with circle sizes up to 11". Wing extrusions slated for the new extrusion press are 105ft in length and weigh up to 90lb/ft with circle sizes up to 40".

"Our company is very cost sensitive," reflects UAC's Scaglione. "Prior to the heavy press expansion, we had no experience with Bosch Rexroth hydraulic systems. Rexroth got their foot in the door by being very competitive up front, and they were fair throughout the project. None of the change orders were out of line, and we had such a great startup that we used only about 30% of the service budget allocated to the project. Since this part was time and materials, this meant further savings for UAC."