micropitting | Gear Technology Magazine

Experimental and Analytical Study of the Effect of Shot Peening on Gear Micropitting and Contact Fatigue Failure

December 12, 2024

Dalia Jbily, Luc Amar, and André Simonneau

This study aims to investigate the effect of this identified type of shot peening on the micropitting resistance of the gear tooth flanks and the macropitting resistance and to compare the experimental results with the calculation results based on standard methods.

Results of ISO/TS 6336-22 Evaluating Full Contact Zone

June 20, 2023

Robin Olson, Mark Michaud, Jon Keller, and John B. Amendola

This investigation reviews calculations using ISO/TS 6336-22 Method A and Method B, comparing the calculations against field results. Extensive reviews were made of geometry, surface roughness, load conditions, and lubricant conditions to best understand the influences of micropitting on each example and the applicability of the calculations to the results.

Nomenclature of Micropitting

August 30, 2022

Robert Errichello

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An overview of the incubation, nucleation and growth, and morphology of this common failure mode, along with the appropriate terminology to describe it.

Case Study of ISO/TS 6336-22 Micropitting Calculation

March 1, 2021

Micropitting per ISO standard explained.

Critique of the ISO 15144-1 Method to Predict the Risk of Micropitting

March 1, 2016

Robert Errichello

There exists an ongoing, urgent need for a rating method to assess micropitting risk, as AGMA considers it a "a very significant failure mode for rolling element bearings and gear teeth - especially in gearbox applications such as wind turbines."

Optimal Modifications on Helical Gears for Good Load Distribution and Minimal Wear

June 1, 2015

Helical gear teeth are affected by cratering wear — particularly in the regions of low oil film thicknesses, high flank pressures and high sliding speeds. The greatest wear occurs on the pinion — in the area of negative specific sliding. Here the tooth tip radius of the driven gear makes contact with the flank of the driving gear with maximum sliding speed and pressure.

Micropitting of Large Gearboxes: Influence of Geometry and Operating Conditions

September 1, 2014

The focus of the following presentation is two-fold: 1) on tests of new geometric variants; and 2) on to-date, non-investigated operating (environmental) conditions. By variation of non-investigated eometric parameters and operation conditions the understanding of micropitting formation is improved. Thereby it is essential to ensure existent calculation methods and match them to results of the comparison between large gearbox tests and standard gearbox test runs to allow a safe forecast of wear due to micropitting in the future.

Morphology of Micropitting

November 1, 2012

Robert Errichello

Understanding the morphology of micropitting is critical in determining the root cause of failure. Examples of micropitting in gears and rolling-element bearings are presented to illustrate morphological variations that can occur in practice.

Case Study Involving Surface Durability and Improved Surface Finish

August 1, 2012

Gear tooth wear and micropitting are very difficult phenomena to predict analytically. The failure mode of micropitting is closely correlated to the lambda ratio. Micropitting can be the limiting design parameter for long-term durability. Also, the failure mode of micropitting can progress to wear or macropitting, and then go on to manifest more severe failure modes, such as bending. The results of a gearbox test and manufacturing process development program will be presented to evaluate super-finishing and its impact on micropitting.

Application of the First International Calculation Method for Micropitting

May 1, 2012

The first edition of the international calculation method for micropitting—ISO TR 15144–1:2010—was just published last December. It is the first and only official, international calculation method established for dealing with micropitting. Years ago, AGMA published a method for the calculation of oil film thickness containing some comments about micropitting, and the German FVA published a calculation method based on intensive research results. The FVA and the AGMA methods are close to the ISO TR, but the calculation of micropitting safety factors is new.