Tribology and Materials | Volume 2 | Issue 3 | 2023 | 88-98
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https://doi.org/10.46793/tribomat.2023.012
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Evaluation of hybrid spindle bearings with nitriding raceway steels under high rotational speeds
Marcus Gärtner
1,
Christian Brecher1,
Stephan Neus1,
Leonardo Catana2,
Feliciano Greco2,
Guillermo Morales-Espejel3,
Defeng Lang3
1 Laboratory for Machine Tools and Production Engineering
(WZL), RWTH Aachen University, Aachen, Germany
2 SKF Industrie S.p.A., Turin, Italy
3 SKF Research and Technology Development, Houten,
Netherlands
Abstract: The further development of high-precision bearings
regarding higher speeds and load-carrying capacity is becoming
increasingly challenging. One approach to meet the increased
requirements is to use new high-performance raceway steels. Particularly
for a highly stressed lubricant film, where seizure may occur, the
bearing material properties can make a key contribution in increasing
the lifetime. In the following, the test results of hybrid spindle
bearings of type 7008 made of nitriding steel are analysed. The bearings
were tested in an endurance run for a constant speed parameter of 2.5
million ndm and a maximum contact stress of 2,900 MPa at the inner ring
contact. The operational behaviour was validated based on the bearing
outer ring temperature and the acceleration level in the test rig. A
further sample test in endurance runs with an increased speed parameter
of 2.8 million ndm and a maximum contact stress of 3,200 MPa at the
inner ring shows that the performance limit of the bearing is even
higher than initially assumed. The microscope analyses of the bearing
steels after the test show low wear. An analysis of the test conditions
in terms of contact stresses, lifetime and the pv value illustrates that
the bearings can run far above standard conditions. The experimental
results show that the operational limits of hybrid spindle bearings with
a raceway made of nitriding steels are significantly higher than
expected.
Keywords: spindle bearings, nitriding steel, high-speed test
rig, contact stresses, lifetime prediction, motor spindles, pv value.
Received: 10-07-2023, Revised: 02-08-2023, Accepted: 16-08-2023
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license, which allows users to distribute, remix, adapt,
and build upon the material in any medium or format for non-commercial purposes only, and only so long as attribution is given to the creator.
2 SKF Industrie S.p.A., Turin, Italy
3 SKF Research and Technology Development, Houten, Netherlands
Abstract: The further development of high-precision bearings regarding higher speeds and load-carrying capacity is becoming increasingly challenging. One approach to meet the increased requirements is to use new high-performance raceway steels. Particularly for a highly stressed lubricant film, where seizure may occur, the bearing material properties can make a key contribution in increasing the lifetime. In the following, the test results of hybrid spindle bearings of type 7008 made of nitriding steel are analysed. The bearings were tested in an endurance run for a constant speed parameter of 2.5 million ndm and a maximum contact stress of 2,900 MPa at the inner ring contact. The operational behaviour was validated based on the bearing outer ring temperature and the acceleration level in the test rig. A further sample test in endurance runs with an increased speed parameter of 2.8 million ndm and a maximum contact stress of 3,200 MPa at the inner ring shows that the performance limit of the bearing is even higher than initially assumed. The microscope analyses of the bearing steels after the test show low wear. An analysis of the test conditions in terms of contact stresses, lifetime and the pv value illustrates that the bearings can run far above standard conditions. The experimental results show that the operational limits of hybrid spindle bearings with a raceway made of nitriding steels are significantly higher than expected.
Keywords: spindle bearings, nitriding steel, high-speed test rig, contact stresses, lifetime prediction, motor spindles, pv value.
Received: 10-07-2023, Revised: 02-08-2023, Accepted: 16-08-2023
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This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license, which allows users to distribute, remix, adapt, and build upon the material in any medium or format for non-commercial purposes only, and only so long as attribution is given to the creator.