With Jim Grann, Ipsen Technical Director
February 4th is “National Create a Vacuum Day,” and Ipsen is proud to celebrate by answering a commonly asked question: Why use a vacuum furnace?
People have been forging metal for ages. Literally.
From the Bronze Age to the Iron Age, advancements in metallurgical technology have marked the rise of civilizations and the expansion of humanity. Swords were forged in fire, quenched in water, alloyed with carbon, and hammered into shape by weaponsmiths. The army with the best weapons and most effective armor had a significant advantage whenever wars were fought. The ability to attack or defend a territory was often determined by the skills of the metal workers at the armory.
As technology advanced, so did the smelting and alloying of metals. During the industrial revolution, assembly lines demanded material consistency and a regular frequency of replenishment. In the US, giant steel mills, with their molten metals that could be seen glowing from miles away, were essential to create modes of transportation that opened up the continent, then the world.
In the early 20th century, radio and television started incorporating the use of vacuum tubes, while the electric lightbulb required the creation of a vacuum around an electrified light-emitting element – typically tungsten. At about the same time, experiments with vacuum furnaces started to show the possibility of industrial applications, and in 1929 the Raytheon Corporation placed their first order for a vacuum furnace.

In 1959, Harold Ipsen experimented with his own vacuum furnace in Rockford, Illinois. Ipsen was designing hot zones, solving quenching conundrums, and experimenting with inert gases to efficiently eliminate oxygen and water vapor. He could see how vacuum furnace technology was going to be a force to reckon with.
Vacuum furnaces were able to deliver heat to a metallic part to change its lattice structure for hardening, aging, or stress relieving, or they could bind one metal with another metal through processes like brazing. By eliminating oxygen and water, rust and other metal oxides were avoided, and vacuum heat-treated parts came out clean and bright. The more efficient the vacuum, the cleaner and brighter the parts.
In the 1960s, the Space Race drove a surge in demand for precision metal alloys and the use of rare and exotic metals. Vacuum heat-treating technologies were employed to ensure parts could be created with high levels of accuracy and dependability. When it comes to manned space travel, predictability and dependability are essential.
Applications for clean and dependable parts also found their way into medicine, helping solve the problem of joint deterioration, particularly in knees and hips. The ability to create durable and lasting replacement joints from alloys of cobalt-chromium, titanium, zirconium, and nickel that are clean even on the microscopic level made vacuum furnaces an essential medical resource.
The precise control that a vacuum furnace has to deliver better uniformity from one process to the next, to handle brazing convoluted geometries, to manage dealloying, control alpha and beta phases, and maintain effective case depth control for carburizing and nitriding makes the vacuum furnace essential to industries that rely on high levels of consistency with very specific metallurgical qualities.
Manufacturers found that parts processed in a vacuum furnace often didn’t need extensive post-treatment cleaning or additional machining. It wasn’t necessary to sand blast or polish parts that were processed in a vacuum furnace. There was a reduced dependence on quench oils, acetylene, or endothermic gas generators. The process, driven primarily by internal electric heating elements with an exterior temperature controlled by a recirculating water system, had no open flames and no associated fumes or soot. With vacuum furnaces, heat-treating facilities could be clean, temperature-controlled warehouses, with far fewer environmental impact issues.
So why do we use vacuum furnaces? Because vacuum furnace technology helps us find ways to go farther and live longer than ever before. And because the most successful human enterprise will always start by giving our visionaries, engineers, designers, and operators the best technology we can make.
