Case Study of ISO/TS 6336-22 Micropitting Calculation

Robin Olson, Mark Michaud, Jonathan Keller

Research output: NRELPresentation


ISO/TS 6336-22 (Calculation of load capacity of spur and helical gears - Part 22: Calculation of micropitting load capacity) is the ISO technical specification containing a proposal for a method to calculate the risk of micropitting in gear sets. It assesses micropitting risk through a safety factor which is calculated as the minimum specific film thickness in the contact zone divided by a permissible specific film thickness. A sliding parameter is used to adjust the film thickness in the contact zone to the region of highest sliding, which is where micropitting has been observed. The permissible specific film thickness is best determined through experience or testing, but there is an option to estimate it based on the lubricant’s failure load stage in FZG testing. This paper is a case study of how the method behaves when applied to several gear sets and applications that have experienced micropitting in the field.
Original languageAmerican English
Number of pages32
StatePublished - 2020

Publication series

NamePresented at the American Gear Manufacturers Association 2020 Fall Technical Meeting, 20 October 2020

NREL Publication Number

  • NREL/PR-5000-77731


  • gears
  • micropitting
  • reliability


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