Tribology and the Control of Friction
An advanced Greek element tribo- and Its Modern Applications
Part 1 of 2
Go to part 2 of tribology
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
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
- 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
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-
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,
“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.”
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
Go to part 2 of tribology