How to Build a 50,000 Ton Forging Press - by Brian Potter

SubscribeSign in

How to Build a 50,000 Ton Forging Press<br>Brian Potter<br>Aug 21, 2024

250

19<br>23

Share

Alcoa 50,000 ton forging press.<br>In the late 1940s and early 1950s, a revolution took place in American military aircraft design. The invention of the jet engine made it possible for aircraft to fly far higher and faster than ever before. While the fastest propeller-driven aircraft of World War II topped out at slightly less than 500 miles per hour in level flight, jet-powered aircraft in the mid-1950s were flying at over 1,300 miles per hour, twice the speed of sound, with even faster aircraft on the horizon. Achieving this level of performance required not only powerful jet engines, but a whole host of new aircraft technologies: materials like inconel and titanium, and manufacturing methods that could produce far stronger and lighter aircraft parts.<br>One promising technological advance was to use large forged or extruded parts. Forging is a manufacturing method that shapes metal by applying pressure, usually by hammering it or squeezing it with large presses. Extruding is a similar process that shapes metal by squeezing it through an opening of the proper shape. At the time, both forging and extrusion were used to produce aircraft parts, but parts were limited in size and needed to be stitched together with hundreds or thousands of fasteners. By using very large forgings and extrusions to replace many smaller parts, components could be thinner, lighter, and stronger. Aerodynamic surfaces could be smoothed, and seals could be tightened. And by eliminating so many individual parts (along with the time and effort to attach them together), large forgings and extrusions could potentially reduce the time and cost required to build an aircraft. While there were a variety of different methods for making very large parts, such as casting and machining from plate or billet, forging and extrusion had several distinct advantages.<br>…Machining from plate or billet requires tremendous machines and many machine-hours. A part machined from plate or billet is not as consistent in its mechanical properties as a part forged or extruded to finished or nearly finished dimensions. Mechanical properties in the center of thick plate or billet are questionable. Forgings have the added advantage of variable grain direction which generally can be tailored to the stress patterns of a specific design. The large percentage of stock going into chips [in machining] is unfavorable. Casting materials do not have sufficiently high physical properties, nor have casting techniques developed to the point where efficient metal distribution and thin sections can be obtained. –  Symposium on Heavy Presses

But the size of forgings or extrusions was limited by the size of the presses used to make them. Very large forgings or extrusions would require building presses of unprecedented size. Machines would need to be ten stories tall and capable of exerting hundreds of millions of pounds of force.<br>In the 1950s, the Department of Defense undertook a program to build such presses. Known as the Heavy Press Program, it funded the construction of four large forging presses and six extrusion presses. Upon completion, the largest of them were the largest presses in the world.<br>The program was an enormous success. Not only did the large parts produced by the presses greatly reduce the cost and increase the performance of military aircraft, but the presses proved useful for making parts for things like helicopters, submarines, spacecraft, and commercial jets. Within roughly a decade the presses had returned more than double their investment in reduced manufacturing costs, and they continued to produce complex, high quality forged and extruded parts over the subsequent decades. Six of the ten presses are still operational today.<br>Origins of the heavy press program

The origins of the Heavy Press Program can be traced to Germany in the 1920s. As a condition of the Treaty of Versailles, Germany was forced to give up many of its western iron-producing regions, creating a chronic shortage of iron and steel. This drove Germany to make greater use of other metals, like magnesium and aluminum. Germany was the first country to produce magnesium on a commercial scale, starting in the 1880s, and it was an early leader in the development and use of high-strength aluminum alloys.<br>It was found that while aluminum and magnesium responded poorly to being shaped by hammering (they tended to shatter, particularly magnesium), good results could be achieved by squeezing them in hydraulic presses. As a result, Germany built a series of increasingly large presses in the years following WWI  to make large forgings and extrusions from magnesium and aluminum. For forgings, it built a 7,000-ton press, followed by three 16,500-ton presses, followed by a 33,000 ton press, with plans for an even larger 55,000 ton press. Progress...