Introduction to Tribology
Why is Tribology Important
Tribology is the study of surfaces moving relative to one another, a phenomenon that affects our lives in a multitude of ways every day. The term tribology is based on the Greek word for rubbing and, although the term itself was not coined until 1964, there are images of tribology in action from as long ago as ancient Egypt, when early tribologists used oil to help facilitate sliding of large statues. Generally, tribology includes three key topics: friction, wear and lubrication. Friction is the resistance to relative motion, wear is the loss of material due to that motion, and lubrication is the use of a fluid (or in some cases a solid) to minimize friction and wear. The field is necessarily interdisciplinary and utilizes skills from mechanical engineering, materials science and engineering, chemistry and chemical engineering and more. Tribology is both technologically-relevant and scientifically-fascinating, and it's definitely an exciting time to be a tribologist! Click here to learn more about traditional applications of tribology.
Everyday Examples of Tribology
In addition to the more traditional applications of tribology, there are many more devices and other products that we use regularly whose functions rely on tribology. They include products and processes that arise in healthcare, sports, nature and more. In some cases we want to maximum the friction (such as on the soles of our shoes) and in others we want to minimize friction (such as on the bottom of a bobsled). Click here to learn more applications of tribology in your everyday life.
Role of Tribology in Energy Efficiency
Tribology is particularly important in today's world because so much energy is lost to friction in mechanical components. To use less energy, we need to minimize the amount that is wasted. Significant energy is lost due to friction in sliding interfaces. Therefore, finding ways to minimize friction and wear through new technologies in tribology is critical to a greener and more sustainable world. Click here to learn more about energy waste due to friction and wear.
Tribology is an interdisciplinary field that includes mechanical engineering; materials science and engineering; chemistry and chemical engineering; and more. This wide variety of skills is necessary because many different physical phenomena occur at a sliding interface. There are also many different areas of focus within tribology. Generally speaking, there are three major topics within tribology: friction, wear and lubrication. Each of these is described in more detail below.
Friction is, by definition, the resistance to motion. The magnitude of this resistance is a function of the materials, geometries and surface features of the bodies in contact, as well as the operating conditions and environment. It is often desirable to minimize friction to order to maximize the efficiency of a component or process. Generally speaking, friction increases with load and surface roughness and can be decreased by the use of a lubricant.
Click here to learn more about friction.
Wear is the loss of materials, usually due to sliding. Typically wear is undesirable as it can lead to increased friction and ultimately to component failure. Like friction, wear is typically minimized by using a lubricant to separate the two bodies so that they do not directly touch one another.
Click here to learn more about wear.
Lubricants and Lubrication
Lubricants are primarily used to separate two sliding surfaces to minimize friction and wear. They also perform other functions, such as carrying heat and contaminants away from the interface. Lubricants are often liquids, typically consisting of oil and added chemicals, called additives, which help the oils better perform specific functions. However, there are some applications where lubricants can be gases or even solids.
Click here to learn more about lubricants and lubrication.
Other Topics in Tribology
There are several topics that are integrally related to the core areas of friction, wear and lubrication, but that deserve their own description. These are surface roughness, contact mechanics and nanotribology. Each topic will be briefly introduced here.
Click here to learn more about other tribology topics.
Content and graphics courtesy of Ashlie Martini. Martini Research Group – Fundamental Tribology (http://faculty2.ucmerced.edu/amartini/tribology.shtml)