Scuffing

Scuffing is the sudden failure of the lubricant layer during operating conditions, normally occurring under high load or high speed. Scuffing is a consequence of a rapid shift in the dynamic equilibrium in the contact zone between the compressed solid-like lubricant film and its operating temperature. An increase in friction due to the relative motion between the solid-like film results in a rapid temperature rise. Ultimately, this rapid rise can meet the lubricant’s flash temperature resulting in an instantaneous breakdown of the lubricant film causing the mating surfaces to contact, weld, and tear away. Scuffing causes a large degradation of the surface’s geometry, leads to inefficiency of the system, and potentially catastrophic failure. Unlike fatigue-based failure modes, where repeated loading and unloading leads to failure after usually millions of cycles, scuffing can happen at almost any point in a component’s life cycle.

REM’s ISF® Technologies are commercially available processes used to decrease surface roughness and improve surface texture. For gear applications, REM’s ISF® Process is known to significantly enhance gear properties and performance. In these gear applications, surface roughness plays a critical factor in increasing pressure by concentrating load in micro asperity regions and generating heat through friction.

The ISF Process can decrease the risk of scuffing by modifying the contact surface texture allowing an increase in lubricant film thickness and reducing surface roughness reduction which combine to significantly increase scuffing resistance[1]. In a study by the University of Cardiff into the effect of REM’s isotropic superfinishing on scuffing resistance, using Cardiff University’s Scuffing twin-disc test bench, REM’s ISF Process was shown to significantly outperform ground specimens as well as “mirror-polished” specimens. All other specimens failed at or before maximum load (4,150 N at Hertizian Pressure of 1.7 GPa); the REM ISF Processed specimens survived all 12 load stages (3 minutes each) and 30 minute endurance cycle at maximum load without failing.

REM’s ISF Technologies can be applied to very wide ranges of components types, sizes, and metals. These processing technologies are available via outsourced processing at a REM facility or as technology installations at a customer site. Contact us today to learn more or to start a project.

 

[1] Snidle, R. W., Alanou, M. P., Winkelmann, L., Michaud, M., “Effect of Superfinishing on Scuffing Resistance,” ASME 2003 Design Engineering Technical Conference, Chicago, IL, September 2003.