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Every major industrialized nation in the world accepts the new bearing-life standard except the U.S. Why-and what does it mean for the industry?
Waiting for the official appearance of any new ISO standard is like waiting for a glacier to calve, only slower. An acclaimed technological breakthrough may wind through the dark halls of science and industry for 10-20 years before emerging into the light of international acceptance because standards must represent an accessible and agreed-upon baseline for everyone, not just the esoteric capabilities of industry leaders.
Yet even against this backdrop, the story of ISO 281:2007, "Rolling bearings - Dynamic load ratings and rating life," is remarkable for the mix of science and opinion that now leaves U.S. bearing users living with standards from the time when the Cold War ended and The Simpsons first appeared on Fox TY
To throw light on this story, TLT interviewed three men who were involved with the development of the new standard: STLE-member Myron McKenzie, chief engineer of the American Roller Bearing Co. in Morganton, N.C. (who suggested this article); Martin Correns, director of advanced engineering analysis and simulation for INA-Schaeffler KG in Herzogenaurach, Germany; and STLE life-member Dan Snyder, recently retired as director of application engineering for SKF in Lansdale, Pa., and now an industry consultant active in the Bearing Technical Committee of the American Bearing Manufacturers Association (ABMA).
We'll recap a history of bearing life calculations, review the startlingly new approach that Stathis loannides and STLE life-member Ted Harris introduced in 1985, describe how that approach evolved into ISO 281:2007 and investigate how the U.S. ABMA has so far not adopted it.
THE FATHERS STILL LIVE
"The 1947 Lundberg and Palmgren report on 'Dynamic Capacity of Rolling Bearings' is still the basis for all the bearing life calculations that are done today," says McKenzie. "They are the fathers of modern bearing life calculations. Before their report, every bearing manufacturer calculated life in its own way." The bearing industry needed a unified method for calculating bearing life.
At the end of World War II, bearings were crude chunks of steel by today's standards, and the Lundberg and Palmgren report, which was based on thousands of SKF experiments, reflected that. "Materials then were full of voids...