When SKF first launched the SKF Explorer performance class in 1999, it set new standards for bearing performance. Driven by customer needs in challenging industrial applications, SKF has raised the bar again to provide additional wear resistance while maintaining toughness, to potentially double bearing service life – particularly in applications where there are high levels of contamination or poor lubrication conditions.
By combining material, design and manufacturing improvements, SKF engineers and scientists were able to maximize the effect of lubrication and minimize the effects of friction, wear and contamination. The result: a performance class of bearings that provided higher load carrying capacity and extended bearing service life that has been confirmed and validated by leading certification bodies, Germanischer Lloyd and Det Norske Veritas.
From a materials perspective, SKF Explorer self-aligning roller bearings were characterised by an extremely clean and homogenous bearing steel that underwent a unique heat treatment process. The purity of the steel gave SKF Explorer bearings their exceptional strength and durability and the heat treatment created the optimal combination of hardness and dimensional stability.
The result was a highly reliable range of self-aligning roller bearings, with low friction, high load carrying capacity and minimized stresses.
Since the introduction of SKF Explorer spherical roller bearings, the SKF Explorer performance class has expanded to include other bearing types including tapered roller bearings, cylindrical roller bearings, deep groove ball bearings and angular contact ball bearings. Today, all standard spherical roller bearings, CARB toroidal roller bearings and most spherical roller thrust bearings are manufactured to SKF Explorer performance class specifications.
Heat treatment adds performance
Now, SKF has further improved the heat treatment for self-aligning roller bearings so that they are even more wear resistant. Though this upgraded heat treatment can improve uptime for virtually any application where reliability and long service life are key operational parameters, the benefits are most apparent in industrial applications where there are high levels of contamination or poor lubrication conditions. Typical examples include the metals, mining, mineral and cement processing industries, wind power and marine, industrial transmission and material hand-ling applications.
Validation testing carried out at centres within SKF and at KTH University in Stockholm, Sweden, showed the improved wear resistance and the service life gain under poor lubrication conditions indicate that these bearings can last up to twice as long as original SKF Explorer bearings. For contaminated conditions, endurance tests similarly indicate a possible doubling in service life when compared with the original SKF Explorer bearings.
Results indicate that medium- and largesize upgraded SKF Explorer bearings can further extend the time from initial spalling to through-fracture. The extended failure mode, when part of a proactive maintenance programme, can virtually eliminate unplanned downtime. The f lange strength of upgraded SKF Explorer spherical roller thrust bearings was tested against original SKF Explorer bearings. After the f langes on the original SKF Explorer fractured, the upgraded SKF Explorer bearings ran twice as long and had only developed spalls.
Even though bearings in process equipment are not run to through-fracture, these tests show that once bearing damage has been detected, upgraded SKF Explorer bearings continue to operate longer, providing more time to plan, order parts and prepare for a shutdown; thereby reducing downtime and its related costs.
Conclusion The contribution that the improved heat treatment provides, to extend the service life of upgraded SKF Explorer self-aligning roller bearings, is significantly improved wear-resistance, which can result in up to twice the bearing service life under poor lubrication or severe contamination conditions. This opens the opportunity for end users to increase equipment uptime in some of the harshest and most challenging industries, from wind power to metals processing.
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