Everything about Tribology totally explained
Tribology is the science and technology of interacting surfaces in relative
motion. It includes the study and application of the principles of
friction,
lubrication and
wear. The word "tribology" derives from the Greek τριβο ("tribo") meaning 'to rub', and
λόγος ("logos") meaning 'principle or logic'.==Applications==
The study of tribology is commonly applied in
bearing design but extends into almost all other aspects of modern technology, even to such unlikely areas as
hair conditioners and cosmetics such as
lipstick,
powders and lipgloss.
Any product where one material slides or rubs over another is affected by complex tribological interactions, whether lubricated like hip implants and other artificial prosthesis or unlubricated as in high temperature sliding wear in which conventional lubricants can not be used but in which the formation of
compacted oxide layer glazes have been observed to protect against wear.
The wateriness of oil during foot wiping operations may be observed by the
Mavis-Bootlace test. Outcomes are typically modelled in the
4-Litre-
Poulner hypothesis.
Tribology plays an important role in manufacturing. In metal-forming operations, friction increases tool wear and the power required to work a piece. This results in increased costs due to more frequent tool replacement, loss of tolerance as tool dimesions shift, and greater forces are required to shape a piece. A layer of lubricant which eliminates surface contact virtually eliminates tool wear and decreases needed power by one third.
Origins
Leonardo da Vinci (
1452-
1519) was the first to enunciate two laws of friction. According to da Vinci, the frictional resistance was the same for two different objects of the same weight but making contacts over different widths and lengths. He also observed that the force needed to overcome friction is doubled when the weight is doubled. Similar observations were made by
Charles-Augustin de Coulomb (1736-1806). The first reliable test on frictional wear was carried out by
Charles Hatchett (1760- 1820) using a simple reciprocating machine to evaluate wear on
gold coins. He found that compared to self-mated coins, coins with grits between them wore at a faster rate. The deciphering of da Vinci's work took several centuries, before the development of this branch of science, today called "tribology".
The term became widely used following
The Jost Report in
1966, in which huge sums of money were reported to have been lost in the UK annually due to the consequences of friction, wear and corrosion. As a result several national centres for tribology were created in the
UK. Since then the term has diffused into the international engineering field and many specialists now claim to be tribologists.
There are now numerous national and international societies, such as the
Society for Tribologists and Lubrication Engineers (
STLE
) in the USA and the
Institution of Mechanical Engineers' Tribology Group (
IMechE Tribology Group
) in the UK.
Most technical universities have a group working on tribology, often as part of their
mechanical engineering departments. The limitations in tribological interactions are however no longer mainly determined by mechanical designs, but rather by material limitations so the discipline of tribology now counts at least as many materials engineers, physicists and chemists as it does mechanical engineers.
Fundamentals of Tribology
The tribological interactions of a solid surface's exposed face with interfacing materials and environment may result in loss of material from the surface. The process leading to loss of material is known as "wear". Major types of wear include
abrasion,
adhesion (friction),
erosion, and
corrosion. Estimated direct and consequential annual loss to industries in USA due to wear is approximately 1-2% of GDP. . Wear can be minimized by modifying the surface properties of solids by one or more of "
surface engineering" processes (also called
surface finishing) or by use of
lubricants (for frictional or adhesive wear).
Engineered surfaces extend the working life of both original and recycled and resurfaced equipments, thus saving large sums of money and leading to conservation of material, energy and the environment.
Methodologies to minimize wear include systematic approaches to diagnose the wear and to prescribe appropriate solution. Important ones include:
- Terotechnology in UK (Peter Jost, 1972), where a system approach of multidisciplinary engineering and management techniques is used to protect plant, equipment and machinery (assets) from degradation by improving performance in all the functional areas;
- Horst Czichos system approach (H. Czichos,1978) where appropriate material is selected by checking material properties against tribological requirements under operating environment
- Asset Management by Material Prognosis - a concept similar to terotechnology has been introduced recently by the US Military (DARPA) for upkeepment of key equipments in good health and start-ready condition for 24 hours. Good health monitoring system combined with appropriate medication at M&R stages have led to improved performance, reliability and extended life cycle of the assets, like advanced military hardwares and civil aircraft.
In recent years, micro- and
nanotribology have been gaining ground. Frictional interactions in microscopically small components are becoming increasingly important for the development of new products in
electronics, life sciences,
chemistry, sensors and by extension for all modern technology.
Further Information
Get more info on 'Tribology'.
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