Vacuum Hardening is an improvement over Conventional Hardening in that the components’ surfaces are protected from possible negative effects of exposure to a gaseous atmosphere. Vacuum treated material is quenched in gas or liquid, depending on the specification requirements. The expression "vacuum hardening" is used here to differentiate the process from conventional hardening. It should also be noted that "hardening" is usually referred to as "quenching".

High strength steel alloys, such as 4340M, 300M, and others, are most commonly used in the manufacture of landing gear components. These alloys are hardened and tempered to produce ultimate tensile strengths exceeding 280 ksi (1,930 MPa). Vac Aero International processes landing gear components for most of the major commercial and military aircraft programs.

Vacuum hardening also prevents decarburization during production. Process parameters can be adjusted in line with the particular material properties to minimize dimensional changes and distortion. The use of vacuum conditions prevents oxidation on component surfaces, thus enabling clean and bright surfaces to be produced. Other advantages of vacuum hardening include nitrogen cooling that can be tailored to each component as well as extremely uniform temperatures in the furnace chamber.