Sliding bearings, according to their friction state, why bearings and what?
2. boundary frictionThe boundary of oil film thickness is less than 1 microns to two metal surface is completely separated from each other, when the movement of two metal surfaces, metal surface asperities will still considerable rubbing cut, this friction is called boundary friction. The boundary friction friction laws, basically the same with the dry friction, the friction coefficient decreases, f = 0.1 ~ 0.3. Although the boundary friction can not completely avoid the metal surface wear, but it can greatly reduce wear and tear.3. fluid frictionWhen the two friction surfaces have sufficient lubricating oil, the oil film thickness is large enough to form a two surface asperity completely separated, the friction between the molecules of the fluid inside only when relative motion is called fluid friction, the oil film is formed under certain high pressure oil film small load, prevent the direct contact between two friction surfaces, so the minimal friction coefficient (F = 0.001 ~ 0.01), significantly reduces friction and wear.
Sliding bearings, according to the friction between the surface of the friction, the friction state is divided into the following:1. dry frictionTwo friction with direct contact with the surface of the movement without adding any lubricant is called dry friction. Dry friction will be accompanied by a great deal of friction, work loss and severe wear, which will cause severe temperature rise and even burn out the bearings in the sliding bearings. Therefore, dry friction is not allowed in plain bearings.
To sum up, fluid friction, also known as fluid lubrication, is the most ideal working environment of the journal. Long term high speed rotating machines shall ensure that the bearings operate under fluid lubrication conditions. In practical use, many friction pairs are in a mixed state of dry friction, boundary friction and fluid friction, known as mixed friction (or incomplete fluid friction).
