Tribology

Tribology is the study of science and engineering of interacting surfaces in relative motion. It includes the study and application of the principles of friction, lubrication and wear. Tribology is a branch of mechanical engineering and materials science.
There are four Elements of Tribology:
• Surface interactions with its environment, including lubrication and lubricants.
• Generation and transmission of forces at the interface.
• Response of materials to the force generated at the interface.
• Design of tribological systems
Polymers play an important part in materials and mechanical engineering, not just for their ease in manufacturing and low unit cost, but also for their potentially excellent tribological performance in engineered forms. In the pristine or bulk form, only a few of the polymers would satisfy most of the tribological requirements.
Tribological applications of polymers include gears, a range of bearings, bearing cages, artificial human joint bearing surfaces.
Similar to the bulk mechanical responses, the tribological characteristics of polymers are greatly influenced by the effects of temperature, relative speed of the interacting surfaces, normal load and the environment.

Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.
Dry friction: resists relative lateral motion of two solid surfaces in contact. Dry friction is subdivided into static friction between non-moving surfaces, and kinetic friction between moving surfaces.
Friction is a very common phenomenon in daily life and industry, which is governed by the processes occurring in the thin surfaces layers of bodies in moving contact. Friction leads to energy dissipation and in micro-contacts, where extreme stress is present, to micro-fractures and surface wear.