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A large shell is removed from heat-treating furnace for quenching. |
In the 1880s, the U.S. Navy wanted to convert its fleet from wooden ships to iron-clad vessels. They asked what was then the Bethlehem Iron Works to build a forge shop to supply the necessary armor plate and gun tubes, offering a $9 million order to facilitate the construction. In 1887, the Bethlehem Iron Company installed two hydraulic forging presses – one 2,000 ton and one 5,000 ton – along with the appropriate heat-treatment and machining facilities to satisfy the Navy’s orders. Ever since, the plant has been a vital supplier of critical components to the Navy.
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An ingot is being prepared to be shipped to LHF’s Bethlehem facilities.
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The Bethlehem forging plant went on to solidify its role as an internationally renowned leader in the production of quality forgings. The company dominated the market for large forgings for the electric power-generation industry, producing the forgings for the large hydroelectric plants built near Niagara Falls. The company also produced the axle for the Ferris Wheel of the 1892 Chicago World’s Fair. Weighing 56 tons, it was then the largest forging ever produced.
Over the years, several different forging presses were built at the site. The current 10,000-ton computer-controlled oil-hydraulic open-die forging press was erected in 1983. The press continues to be the largest open-die press in the Western Hemisphere. The smaller 3,000-ton press was converted to oil hydraulic in 1998. The name of the facility also evolved with the passage of time in several steps to BethForge, a subsidiary of Bethlehem Steel Corporation. In 1997, Whemco Inc., a Pittsburgh-based supplier of heavy industrial components, preserved the facility by purchasing it from Bethlehem Steel and renaming it Lehigh Heavy Forge. Since the acquisition, significant investments have been and continue to be made in press and manipulator upgrades, forge and heat-treatment furnace rebuilds, and the addition and modernization of machine tools.
Today, LHF is a leader in the production of components for the Navy, pressure vessels, commercial nuclear forgings, large-diameter backup rolls, work rolls, power-generation equipment, marine equipment, ship shafting, billet and large industrial components.
Precision Forging and Other Capabilities
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Ingot being blocked under LHF’s 10,000-ton press. |
For more than 120 years, LHF has been producing large open-die forgings for critical applications. All of the manufacturing steps are controlled by strict manufacturing plans. The large forgings produced at LHF require highly refined steel made from ingots weighing up to 300 tons teemed at ArcelorMittal’s Steelton Plant. Steel for LHF’s heavy forgings is melted in an electric arc furnace and ladle refined to consistently meet restrictive chemical and cleanliness requirements. From there, the steel is double degassed – ladle degassed while being argon stirred followed by Vacuum Stream Degassing (VSD) – a process pioneered in Bethlehem in the 1950s. With both degassing operations occurring at less than 1 torr, the process removes detrimental levels of hydrogen. Once solidified, the ingots are shipped hot to LHF’s Bethlehem facilities.
The centerpiece of any forging operation is the forging press. LHF has two open-die forging presses: a 3,000-ton press for billets and work rolls and a 10,000-ton press for making large parts. Both press lines have rail-mounted manipulators and auxiliary water cranes to permit the forming of complex shapes. When ingots arrive, they are heated to forging temperatures in large car-bottom furnaces prior to deformation under the press. Once forging is complete, the newly formed part undergoes a preliminary heat treatment in certified furnaces up to 16 feet in width and 70 feet in length. For the quality final heat treatment, depending on the material and desired properties, the large pieces can be quenched in water, oil or air.
The quench tanks include deep horizontal designs 51 feet in length by 11 feet in depth as well as vertical tanks 22 feet in diameter by 15 feet in depth. For certain applications, spray quenching or cryogenic treatment boxes are also used. To verify that the required mechanical properties are met, LHF has an in-house testing laboratory where tensile and Charpy specimens are tested with a temperature range capability of -320°F to 350°F. The lab also performs hardness testing, macro etching and various metallographic inspections.
LHF’s machine shop houses large computer-controlled machine tools. There are 11 CNC lathes up to 80 feet in length, with up to a 100-inch swing. The company’s boring capabilities are unique, with two boring lathes capable of trepan boring shafts up to 80 feet long from one end. If required, the bore can be finished on either of their two 80-foot-long honers. Parts with unique geometries are machined on one of nine horizontal boring machines, four of which are CNC-controlled with spindles up to 10 inches in diameter. Pressure-vessel cylinders, discs and domes necessary for the commercial nuclear industry are machined on one of the company’s seven vertical boring mills. With CNC vertical mills up to 25 feet, many shapes and configurations are possible. Additionally, the company has a host of other equipment like planer mills, band saws, and CNC and conventional grinders.
Governed by LHF’s quality system, which is ISO 9001-2008 registered, the forgings are checked to ensure a high level of quality before, during and after machining. All quality control testing is conducted by personnel who are qualified to perform ultrasonic, liquid penetrant, magnetic particle and dimensional inspections. A senior-level nondestructive-testing engineer oversees all inspections. All measuring instruments are certified by the in-house metrology laboratory, and the pyrometry lab certifies the temperature-measuring devices.
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A workpiece is upset under LHF’s 10,000-ton press. |
Large Forgings for Large Operations
The components that LHF produces are critical to many industries, including defense, steel production, fossil-fuel power generation, hydropower generation, commercial nuclear-power generation, mineral processing and mining, marine equipment, and other general industries. For the steel industry, the company produces backup rolls, including plate-mill backup rolls weighing in excess of 150 tons. LHF is also a global supplier of work rolls to the world’s rolling mills. Fossil power-generation components produced include generators, turbine rotors, discs, couplings and jackshafts. Heavy-walled cylinders and shafts for generators are made for the hydropower industry. Pressure-vessel components such as domes, heads, discs and heavy-walled cylinders are produced for the commercial nuclear power and other industries. Many different types of shafts are produced for various uses in the mining industry – rock crushers, drum shafts, draglines, etc. LHF forges propulsion shafts and rudder stocks for the shipbuilding industry. Forgings for nuclear-powered Navy ships are also produced. Custom components for press building include platens and tie rods to die blocks.
Expansion Ahead
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A ship’s shaft is forged on the 10,000-ton press. |
LHF is currently planning a multimillion dollar expansion that will eventually increase its capacity to process large forging ingots by 100%. All of the design and engineering for the expansion, which will be done in phases, has been completed. The expansion’s initial phase will increase ingot processing capacity by 40%. Subsequent phases will increase the ingot quantity by 100%. This move in the face of economic uncertainties is evidence that LHF plans to strengthen its position in the large open-die forging market. With the expansion, Lehigh Heavy Forge will be able to provide reduced lead times on large forgings.
For further information on Lehigh Heavy Forge, readers may call 610-332-8100; fax 610-332-8101; e-mail sales@lhforge.com; or visit www.lhforge.com. All photos courtesy of Lehigh Heavy Forge.
