The expert bearing engineers at SKF Aeroengine North America had a challenge. SKF was notified by a customer that several commercial jet turbine main-shaft engine bearings had been removed from service prematurely. An alarm was activated in the early stages of each event, minimizing damage to a single spalled ball in most cases.
SKF suspected that an inclusion was the cause of failure, but normal techniques could not reveal this. To present evidence to their material supplier that the bearing failures were caused by subsurface inclusions, SKF selected serial sectioning analysis using Robo-Met.3D® to investigate this failure.
UES’ expert Robo-Met.3D teams achieved these objectives. They:
- Analyzed a 300x300x840 micron volume of a failed SKF bearing
- Identified and analyzed a butterfly formation associated with subsurface stressed regions
- Uncovered an inclusion of about 400 microns that initiated this formation
- Matched its morphology to two classifications as defined by ASTM E45, Type A-Sulfides and Type C-Silicates
The results, a collaboration between SKF, AFRL, and UES, have been published as Ganti, S., Turner, B., Kirsch, M., Anthony, D., McCoy, B., Trivedi, H., & Sundar, V. (2018). Three-dimensional (3D) analysis of white etching bands (WEBs) in AISI M50 bearing steel using automated serial sectioning, Materials Characterization 138 (2018) 11–18.
Find the full publication here: Three-dimensional (3D) analysis of white etching bands (WEBs) in AISI M50 bearing steel using automated serial sectioning.
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