Lubricants

Lubricants A lubricant (also sometimes called as “lube”) is a substance (usually a liquid) introduced between two moving surfaces to reduce the friction between them which in turn improves the efficiency and reduces the wear. It also has the function of transporting foreign particles. A good lubricant possesses the following characteristics: High boiling point Low freezing point High viscosity index Thermal stability Hydraulic Stability Demulsibility Corrosion prevention High resistance to oxidation Lubrication is the process, or technique employed to reduce wear of one or both surfaces in close proximity, and moving relative to each other, by interposing a substance called lubricant between the surfaces to carry or to help carry the load (pressure generated) between the opposing surfaces. The interposed lubricant film can be a solid, (e.g. graphite and MoS2 etc.) a solid/liquid dispersion, a liquid, a liquid-liquid dispersion (a grease) or, exceptionally, a gas. Types of lubrication are shown in Fig 1. Fig 1 Types of lubrication Besides doing the function of lubricating, lubricants also carries out some or all of the following functions: Act as a coolant to remove the frictional heat which may be sometimes considerable. Keeps moving parts apart. Reduces friction between moving parts It dissolves and transports contamitants and debris arising both from internal and external sources. Acts as a hydraulic medium in some applications It protects against wear of highly loaded machine parts It prevents corrosion and rusting of machine parts It helps in transmitting power It offers protection against the accumulation of deposits (sludges and varnish) in lubrication system. It acts as a seal for gases It resists aeration and foaming, which can cause mal-functioning It resists or aid emulsion formation in wet systems. It stops the risk of smoke and fire of objects It has ability...