Introduction To Lubricants
Definition of Lubricant:
A Lubricant is a substance that reduces force of friction between two surfaces. It includes engine oils, gear oils, hydraulic oils, industrial oils and greases.
Features of Lubricant:
Following are the basic features of lubricant Cools hot areas of an engine and moving parts. To reduce friction: improving engine efficiency and reducing fuel consumption. To protect mechanical parts against wear and corrosion: guaranteeing long life and efficiency of the engine. To keep the engine clean : guaranteeing long engine life and keeping all engine parts in a good and clean condition, while evacuating any impurities to the oil filter and through oil changes. Formulation of lubricants is comprises of base oil and additives. An additive is a substance added in small amounts to base oil to improve, strengthen the formulation of lubricant. Additives also make a contribution, especially with detergent and dispersant additives, the additives fight humidity and corrosion.
Synthetic VS Mineral oil:
Synthetic lubricants are made up of molecules that have been modified under complex chemical processes and allow for enhanced performance under extreme conditions of temperature, pressure and forces. Mineral lubricants are composed of molecules present in crude oil that are separated in the distillation process at a refinery.
It is behavior of lubricant when temperature changes. A liquid that has a relatively high resistance to flow can be described as viscous. For example, water has a low viscosity compared with honey, so in this case honey has a higher viscosity than water under the same temperature. A good quality lubricant keeps its viscosity steady under different temperature and usage conditions for a longer period of time.
Multi Grade VS Mono Grade:
An engine oil fulfills a number of crucial functions and failing in any one of them, may be catastrophic. A good engine oil must be able to hold in suspension contaminants such as carbon (soot) particles, by-products of fuel combustion, neutralize organic acids, protect against rust and corrosion and dissipate the heat generated from the combustion cycle and it must do all of these things under tremendous heat and pressure without succumbing to fatigue. Yet the most important function of a lubricant is to lubricate and reduce friction. Lubricants that are able to maintain their performance in high and low temperatures are called multi-grade. They are defined by two numbers. The first (followed by a “W”) indicates the lubricant’s viscosity under lower temperatures. The second and higher number indicates the lubricant’s viscosity under greater temperatures. A multi-grade lubricant minimizes viscosity differences under temperature variations. For Example a SAE 15W-40 engine oil typically meet the ’15W’ requirements giving protection to -15 degrees Centigrade in winter and it has same thickness as an SAE 40 (mono-grade) under greater temperatures. The mono-grade viscosity designation describes the fluidity of the oil at 100 degrees Centigrade – with higher numbers corresponding to thicker oils. Common viscosity grades for mono-grade engine oils are SAE 30, SAE 40 and SAE 50. However, the mono-grade viscosity describes only the viscosity of the oil when the engine is hot. Typically mono-grade oils are unsuitable for use in cooler climates, as they may thicker unacceptably even at temperatures as modest as 0 degrees Centigrade.