2024 Q1 Spokesman Abstracts
Bevel Gear Grease Case Study Continued – Mechanisms Revealed
Johan Leckner, Axel Christiernsson International AB, Nol, Sweden, Department of Machine Design, KTH Royal Institute of Technology, Stockholm, Sweden
Akepati Bhaskar Reddy, Department of Machine Design, KTH Royal Institute of Technology, Stockholm, Sweden
Jeffrey James Black, School of Chemistry, University of New South Wales, Sydney, Australia
Jason B. Harper, School of Chemistry, University of New South Wales, Sydney, Australia
Sergei Glavatskih, Department of Machine Design, KTH Royal Institute of Technology, Stockholm, Sweden
Abstract
Last year at the annual meeting some of the authors reported on a sustainability case study for nutrunner bevel gear greases. It was shown that by using modern grease technology, friction losses can be reduced by a third and gear life extended threefold. The authors also reported results from a five-year field trial combined with a comparative cradle-to-grave LCA for the grease and gear as one unit, illustrating the importance of performing LCA with a system perspective.
This year the authors will dive deeper into the mechanisms of why the newly developed grease performs significantly better than the reference grease. To perform this study a test simulating the highly loaded gear contact was developed using a rolling-sliding contact. Using this approach, the authors have replicated the results from the gear bench test and isolated the most important factors contributing to extended gear performance.
It is demonstrated that thickener selection plays a critical role affecting both the lubrication mechanism and the tribofilm formation. The latter is extensively investigated using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) giving a previously unavailable, detailed understanding of the tribofilm composition which, in turn, provides information on the chemical processes occurring during the tribological experiments.
To wrap the paper up the authors also take a glimpse into the future and more specifically the performance gains that are possible in gear contacts by using novel additive chemistries.
Six Years On – An Update on Navigating the Lithium Crisis
Gareth Fish, PhD CLS CLGS
Chris Hsu, PhD
Robert Dura, PhD CLGS
Devon McCune BS
The Lubrizol Corporation, Wickliffe, Ohio, USA
Abstract
The most important difference between a lubricating grease and a liquid lubricant is the thickener. This gives the grease its structure and properties. The thickener is responsible for the non-Newtonian behavior and characteristics of the lubricating grease. Since Clarence E. Earle first filed for a US patent in 1940 for the use of lithium soaps as lubricating grease thickeners, lithium thickeners still dominate the market, with 69.1 wt% of the market. 2013 was the peak production for lithium greases, with 76.6 wt% of the market and a global production volume of 905,300 MT.
In 2016, the price of lithium hydroxide soared from its 2015 cost. At the 2016 NLGI Annual Meeting, coffee break chatter was mostly doom and gloom. In the 2017 to 2020 timeframe, the supply pressure eased, with an increase in supply and easing in demand caused by Covid-19. As the economies of the world got back on their feet, demand for electric vehicles soared exponentially as did the price of lithium. As reported earlier this year, the price of lithium went through the roof with prices hitting more than US$90 per kg ($40 per pound) in December 2022, with significant shortages and supply issues.
This paper will review the proposals from 2017 in how to reduce the dependency on lithium thickeners for both commodity and premium grease markets and offer some revised thoughts on how to move forward.