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Tribology and the Control of Friction

An advanced Greek element tribo- and Its Modern Applications

Part 1 of 2
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The “advanced words” in the following article contain valuable information if for no other reason than that the concepts of tribology are so important in all of our lives. You may find some aspects difficult to comprehend, but just knowing what the Greek element tribo means, as well as some of the English words that are derived from it, will give you knowledge that is lacking even among many who are considered “well educated”.

Tribology and Its Essential Progress in the Successful Operation of Machines

The subject of this writing will explain a term that is relatively new based on an element from Greek that is used in modern engineering and physics: tribology. This Greek tribo- element means, “friction, rub, grind” or “to wear away”.

Most of the information for this subject came from an article, “Better Ways to Grease Industry’s Wheels,” from the September 28, 1998, issue of Fortune magazine written by Ivan Amato.

  • Lubrication is central to machine performance, but it’s only part of the story. More and more, the bigger picture of machine health has been going by the label “tribology” [trigh BAH loh gee] which is based on the Greek word for “rubbing, grinding”, or “wearing away”, etc.
  • Tribology combines issues of lubrication, friction, and wear into a complex framework for designing, maintaining, and trouble-shooting the whole machine world.
  • Tribology is already providing data that could be used to produce transmission fluids that give automobile drivers better fuel economy and a smoother ride.
  • The most visionary tribology advocates and practitioners tend to view their field as the cure for much of what ails industry and even entire economies.
  • Tribology has evolved into a bona fide field of research and technology since 1966, when a group of industrialists in England coined the term with assistance from an editor of the Oxford English Dictionary.
  • The O. E. D. defines tribology as, “The branch of science and technology concerned with interacting surfaces in relative motion and with associated matters (as friction, wear, lubrication, and the design of bearings).” In 1968, H.P. Jost, in the February 8, 1968, issue of the New Scientist states, “After consultation with the English Dictionary Department of the Oxford University Press, we chose the term ‘tribology’.”
  • Many tribologists devote themselves to uncovering the fundamental chemical and physical dramas that underlie good and bad lubrication, friction, and wear. They are relying on new tools like friction-force microscopes, that can examine surfaces down to the molecular level (nanotribology?).
  • Transmissions are just one place where tribology makes a difference in the automotive industry. Other items on the agenda include controlling brake noise and wear, reducing internal friction in engines, and increasing the productivity, part quality, and energy efficiency of production machinery.
  • The “tribology tribe” points proudly to its crucial role in the thirty-billion dollar-a-year data-storage industry. When it comes to surfaces in motion, this is an especially harrowing arena. Yet it’s through tribological know-how that makers of hard-disk drives have been able to squeeze more and more data into less and less space.
  • The head that reads and writes information to and from a hard disk flies about 50 to 100 nanometers above the disk surface. That’s about one-thousandth the width of a human hair. Meanwhile, the disk typically spins beneath the head at about ten to twenty meters per second.
  • Woody Monroy, head of corporate communications for Seagate Technology, which makes disk drives, says that in terms of speed and clearance, it’s the equivalent of an F-16 jet fighter plane flying one-sixty second of an inch [less than one millimeter] above the ground, counting blades of grass as it goes, at Mach 813 (or 813 times the speed of sound).
  • There are many reasons computers go down, but one of the most dreaded is when the head assembly literally crashes into the spinning disk’s surface, tearing up and destroying precious data.
  • It’s a tribological triumph that, despite all the hazards, vulnerabilities, and abuse by users, most storage systems operate fine most of the time because of proper coatings. The first protective layer is at most twenty nanometers thick. One leading-edge tribo-tactic is to fiddle with the molecular structure of the thin lubrication layer on top of the disk (nanotribology?).
  • Tribologists have plenty of challenges to keep them busy, but it’s all part of making disk drives and economies run smoothly.

Additional Terms in Tribology

Additional words that I found that are derived from the Greek element tribo- include:

nanotribology, [no dictionary, that I can find, has a definition for this term. J.R.] The following definitions came from various sources on the Internet.

First, on Thursday, January 21, 1999, I received the following information from Dr. Jacqueline Krim, Professor of Physics at North Carolina State University, Raleigh, North Carolina:

“Thank you for your inquiry. Yes, I coined the term nanotribology in a paper I wrote in 1991, entitled, ‘Nanotribology of a Kr [krypton] monolayer: A Quartz Crystal Microbalance Study of Atomic-Scale Friction’, J. Krim, D. Solina and R. Chiarello, PRL, 66, (1991) p. 181-184.”

“I would define nanotribology as the sub-field of tribology involving contact geometries which are well-characterized at atomic length or time scales. These tend to be on the order of nanometers and nanoseconds.”

“JK”

Secondly, on Friday, January 22, 1999, I received another clarifying definition that I had requested from a contact I found on the Internet.

I asked for a simple, easy to understand definition of “nanotribology” and this is what he sent to me:

“Tribology is the science and technology of two surfaces in relative motion which encompasses friction, wear and lubrication. Nanotribology allows the study of friction and wear processes on nanoscale.”

Prof. Bharat Bhushan
Ohio Eminent Scholar and The Howard D. Winbigler Professor Director,
Computer Microtribology and Contamination Laboratory
Department of Mechanical Engineering,
The Ohio State University Columbus, Ohio

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