Types of tribological friction: Definition and examples

Anyone dealing with large or small machines will sooner or later come across the term “tribology”. In this article, you will find out exactly which area of science is concealed behind this term and how tribological approaches influence everyday life in the industrial and mechanical engineering sectors.

What does “tribological” mean? – A definition

Tribology is the science of friction – the scientific study of friction and the phenomena associated with it, such as the wear or lubrication of bearings, guides, gearboxes, engines and other machine components. Therefore, according to this definition, “tribological” applies to everything that is studied within this area of scientific theory. Tribology is subject to interdisciplinary study in the specialist fields of physics, chemistry, mechanical engineering and materials science. Since external friction between two bodies can never be generated by one object alone, we also speak of “tribological systems”.

Examples of tribological friction

Alongside trials and studies that tend to be of a more theoretical nature, friction according to the science of tribology also plays a major role in “real life” situations, where it often goes unnoticed by those actually using the respective parts. Whether we are talking about large machines in an industrial or factory setting or components for everyday usage: Tribological questions crop up in numerous practical areas of application.

Example 1: Friction between components

Brake and clutch linings in vehicles, such as cars, are permanently exposed to mechanical friction – as this is the only way for them to be able to perform their tasks. Here, tribology helps to find a compromise between maximum braking effect and minimum wear. Special materials, such as metal sulfides, ensure that high temperatures are avoided under load and that wear and tear is kept to a minimum. You can also approach the question of how to avoid unwanted vibrations and noises that may arise as a result of friction using tribological findings.

Example 2: Friction between the tool and the chip

Likewise, it is impossible to imagine machining components without friction in the tribological sense. The role that tool wear plays, especially where particularly hard materials require machining, should not be underestimated. This mainly concerns the machining methods used within a tribological system, such as, for example:

  • Turning
  • Boring
  • Milling
  • Planing
  • Sawing
  • Filing
  • Grinding

Quite often, not only the desired sections are stripped off the components in the above cases. The tools themselves are also constantly being worn down through the friction resulting from the particles thereby produced. The degree of abrasion depends on the hardness of the working material.

Example 3: Biotribology

Another area of focus is the so-called field of biotribology. This deals, in particular, with friction phenomena in biological, natural systems – for example in the human body. Among other things, biotribology is searching for ways of making artificial joints more comfortable to use. For hip joints, for example, one often resorts to using titanium which is considered to be highly compatible with the human body. In this case, the friction that arises between the acetabulum and the femoral head needs to be minimised to the greatest extent possible in order to ensure a high level of comfort for the user. This is where biotribology comes into play, examining suitable lubricants, coatings and similar to find the best possible solution.

Tribology and sustainability

Scientists and engineers are now discovering more and more potential, especially when it comes to friction in classic mechanical engineering and general industrial environments. This is because drawing the right conclusions, such as using suitable lubricants, not only means increasing the quality and service life of the different components. If friction and wear are optimised, the environment also benefits. In a study conducted in 2017, tribology was found to have a considerable impact on worldwide energy consumption. According to this study, almost 23 % of global energy consumption is attributable to tribological contacts. Using the right tribological technologies, energy loss due to friction and wear could be reduced by up to 40 % in the long term – especially in the transport and power generation areas.

So, if you dive deep into the topic of tribology you can not only save money and achieve higher customer satisfaction levels, but you can also have a real impact on our future.

Tribology: An area of expertise that is often underestimated

Ultimately, all types of mechanical friction are “tribological” as per definition. However, the study of tribology offers numerous opportunities. Those who are familiar with the phenomena associated with friction are able to make better decisions on which materials to use or what to purchase, exploit previously unused potential when developing their products and even contribute to achieving a sustainable coexistence.

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