Space-age steel technology places bearings on a higher performance
platform
Cronidur 30, a new steel that has been used successfully in the engines
of the space shuttle, exceeds the fatigue life and speeds available from
other bearing steels, with the added benefits of superior corrosion and
wear resistance. Bearings manufactured from the material are unique to
FAG/Barden and are claimed to withstand up to 40% higher dynamic loads,
achieve higher constant operating speeds with grease lubrication, and are
up to 100 times more corrosion resistant than bearings manufactured from
AISI 440C, the standard corrosion resistant bearing steel.
The steel was developed by FAG in co-operation with Bochum University and
VSG Energie, and has proved its reliability and toughness both in the
extreme high temperature conditions of the main engines of the space
shuttle and in the low temperature conditions encountered on the flaps of
commercial airlines.
The bearing material can also improve the performance and reduce the life
cycle costs of machine tools and other demanding applications. In tests,
installed in the spindle of a machining centre, a grease-lubricated (70mm
ID) Cronidur 30 bearing ran at a constant speed of 20,000 rpm with even
temperature behaviour. This contrasts with the 15,000 rpm achieved in the
same test by an SAE52100 (100Cr6) bearing with identical dimensions. In
addition, the material has good corrosion resistance. A measure of a
materials corrosion resistance is its passive current density value. In
this respect Cronidur 30 is better, by about a factor of 100, than 440C,
the standard corrosion resistant steel.