Creating industrial friction
Tribogyr puts bearing contacts and lubricant film to the test.
The Tribogyr test machine at the National Institute of Applied Sciences (INSA) in Lyon, France is breaking new ground in the study of interacting surfaces in relative motion, and the behaviour of lubricants under friction and wear, factors that influence bearing design.
Established in 1957, the institute is one of the largest engineering schools in France, providing a fully integrated approach to education, research and innovation. It collaborates with other leading universities internationally and fosters strong relationships with industry, such as its partnership with Swedish bearing manufacturer SKF.
One area of focus is the multistage analysis of lubricated contacts, which is performed by the Tribogyr test machine, often referred to as “the Beast of Lyon.” This complex, six-tonne contraption of metal alloys, sensors and computers housed in its own environmentally controlled room sits on a special pad to isolate it from outside vibration. It’s the largest and most sophisticated test machine ever built to measure friction and lubricant film thickness in heavily loaded bearing applications.
The machine, designed by the Contacts and Structural Mechanics Laboratory (LaMCoS) at INSA and operating since 2005, provides new insights into the behaviour of friction in rolling elements.
Tribogyr simulates the friction behaviour at full scale, which means it handles forces up to 3,000 N. It operates at speeds of up to 22,000 rpm, measuring frictional forces and moments in different directions given independently by the two contacting surfaces – the rolling elements and the flange. The contact gap can be five millimetres – huge for heavily loaded lubricated contacts.
“At full operating conditions, the contact could generate more than 10 kilowatts of heat dissipation, compared with a large commercial test machine of less than one kilowatt,” explains Guillermo Morales-Espejel, a visiting professor at INSA and a senior scientist at the SKF Engineering and Research Centre in the Netherlands.
“Large size spinning contacts don’t behave like small-size sprinning contacts. Larger contacts have larger surface velocity asymmetry within it. Film thickness and friction are determined by the speed of [the moving] surfaces. Asymmetry in the speed means asymmetry in the film thickness and the created friction, which is not easily calculated.”
But it can be measured. The major benefit of the Tribogyr is its accuracy. Thanks to new research it also measures film thickness. This supplies an image of lubricant flow that provides information about its behaviour.
Looking to the future, Tribogyr is opening up new testing and simulation opportunities as it continues to demonstrate how collaboration between research and industry delivers worthwhile results for both.
Source: Evolution – the business and technology magazine from SKF (www.skf.com).
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This article appears in the March/April 2013 edition of PLANT West.