Micropitting is a progressive, fatigue-based failure mode that occurs in both gears and bearings.  It Micropitting results from the interaction of peak asperities at a micro-scale, and it leads to the gradual erosion of the distressed surface. This deformation can grow to become macropitting and/or component failure. Alternately, micropitting can self-arrest, but as it will always result in an alteration to tooth profile, it can increase noise, harshness, and vibration (NVH), lower efficiency, and/or progress to alternate failure mode such as abrasive wear and/or scuffing.  Micropitting most commonly occurs in case-carburized steels that experience high loads but can occur anywhere hardened metal to metal surfaces come in contact and have the requisite peak asperity interaction.

REM’s ISF® Process is a novel and proven approach to eliminating micropitting by removing peak asperities, generating a higher load-bearing surface, and increasing the lamba lubrication values. These surface finish/texture improvements make any metal to metal interaction significantly less likely to occur and effectively eliminate the failure mechanism that generates micropitting. Numerous public and proprietary studies have shown how effective REM’s ISF Process and the ISF® Surface that it generates is in eliminating micropitting.

One such study using FZG C-gears showed that ISF Processed gears exhibited no profile deviation and no micropitting through both load stage and endurance testing despite the test gear profile being specifically designed to induce micropitting.[1]

In addition to being an optimal manufacturing step to eliminate micropitting as a potential operating failure mode, components that have been damaged by micropitting can often be repaired via REM’s ISF® Process to a better than new condition.  See REM’s refurbishment page for more information.

REM’s ISF Process can be applied to all ranges of gears and bearings, from those with a tip diameter of  <1/2” (~13 mm) and a diametral pitch (DP) of 96 (0.2645 mm module) gears used in critical space applications, to wind turbine annulus gears exceeding 78” (2 meters) in tip diameter.  For installed process applications where low work-in-process (WIP) inventory is desired, REM’s Rapid ISF® Process can deliver full isotropic superfinishes in as little as five minutes.  Available as either an outsourced process or a technology installation, REM’s ISF® Technology is the optimal solution to eliminate micropitting problems, to increase your micropitting safety factor, and/or to optimize your gear/bearing design.

Have an application that is suffering from micropitting or a design that would benefit from an increased micropitting safety factor?  Contact us today to learn more or to start a project.Micropitting SampleUsed, ISF® Processed Wind Turbine Planet Gear, >5 years operation & no signs of micropitting or contact pattern.

[1] Winkelmann, L., El-Saeed, O., Bell, M., “The Effect of Superfinishing on Gear Micropitting, Part II”, AGMA 08FTM10, 2008