Lubrication General and Overview

Lubrication General and Overview

Purpose of lubrication. The primary purpose of lubrication is to reduce wear and heat between contacting surfaces in relative motion. While wear and heat cannot be completely eliminated, they can be reduced to negligible or acceptable levels. Because heat and wear are associated with friction, both effects can be minimized by reducing the coefficient of friction between the contacting surfaces.;

Lubrication is also used to reduce oxidation and prevent rust; to provide insulation in transformer applications; to transmit mechanical power in hydraulic fluid power applications; and to seal against dust, dirt, and water.

Lubricants. Reduced wear and heat are achieved by inserting a lower-viscosity (shear strength) material between wearing surfaces that have a relatively high coefficient of friction. In effect, the wearing surfaces are replaced by a material with a more desirable coefficient of friction. Any material used to reduce friction in this way is a lubricant. Lubricants are available in liquid, solid, and gaseous forms. Industrial machinery ordinarily uses oil or grease. Solid lubricants such as molybdenum disulfide or graphite are used when the loading at contact points is heavy. In some applications the wearing surfaces of a material are plated with a different metal to reduce friction.