Session: CT-05-01 Threaded Fasteners

Paper Number: 153341

153341 - Temperature Dependence of Lubricated Threaded Fastener Release Performance 

Abstract: 

Threaded fastener lubricants need to provide effective lubrication up to the end of the service cycle of a bolted joint. They must provide a practical release torque, resist galling and seizure of the fastener surfaces, and enable effective disassembly. Higher temperature operations often increase the occurrence of galling, seizure and excessive release torque. The rated upper temperature limits of lubricants do not necessarily adequately describe the variations in performance at different operating temperatures that are encountered in service.

The changes in composition and decomposition of different lubricant technologies were measured from 30 to 780°C using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Lubricant components decompose at different temperatures: Some of these reactions include a significant mass change of the lubricant film. By understanding the materials present in the lubricants at different temperature points, their effectiveness was investigated. These were correlated with release torque data for lubricated A2-70 fasteners that were aged at the same temperatures.

Especially significant changes in release torque occurred between 250 and 420°C, when decomposition of the base fluids progress through different stages. Above 380°C, lubricating solids defined the release lubrication performance: Different lubricant technologies varied widely in performance between 380°C and 780°C: Metal, non-metal and lamellar solids were most effective at different temperatures.

Presenting Author: Christopher J Dyson ROCOL, A Division of ITW Limited

Presenting Author Biography: Chris Dyson first encountered tribology during his Mechanical Engineering studies at the University of Leeds. After graduating, Chris did a PhD in engine tribology followed by a few years of collaborative industrial-academic research. Since 2013 Chris has worked for ROCOL, a specialist lubricant manufacturer in Leeds, UK, keeping collaborative links with the Universities of Leeds and Bradford. Since 2024 Chris has been based in Baton Rouge, Louisiana leading a field-based team of consultative lubrication and metalworking specialists, supporting current reliability needs, and developing insight to address emerging and future challenges.

Authors:

Christopher J Dyson ROCOL, A Division of ITW Limited
Jamie Nuttall ROCOL, A Division of ITW Limited
Martin Priest Faculty of Engineering and Digital Technologies, University of Bradford
Malcolm F Fox Faculty of Engineering and Digital Technologies, University of Bradford