Lubricants

Description

Lubricant is a substance that is used in between moving surfaces to reduce friction. Almost all types of machinery and equipemnt has moving parts that rub against each other. Due to this rubbing effect, a resistive force disturbs the movement of the parts. This resistance is known as friction. This friction causes a lot of wear and tear of surfaces of the moving parts and can also result in worn/shedded metal particles damaging related surfaces.  Due to the frictional effect, a large amount of energy dissipates in the form of heat and as result; the efficiency of the machine is reduced.

Functions

The main functions of lubricants are listed below:

• It prevents the direct contact between the moving surfaces and reduces wear, tear and surface deformation of the concerned parts
• It reduces wastage of energy so that efficiency of the machine is enhanced
• It reduces the frictional heat and thus prevents the expansion of metals
• It acts as a coolant by removing the frictional heat generated due to the rubbing of surfaces
• Occasionally, it acts as a seal preventing the entry of dust and leakage of gases at high pressure

Types

Lubricants are classified based on their physical state as follows:

• Liquid lubricants
  1. Vegetable or natural oils - palm oil, castor oil, etc
  2. Soaps
  3. Animal oils - whale oil, tallow oil, etc
  4. Mineral oils - petroleum fractions
  5. Synthetic lubricants - silicones, polyglycol ethers, etc
  6. Blended oils (or) compounded oils - mineral oils with various additives

• Semi-solid lubricants
  1. Greases, vaselines, waxes, etc.

• Solid lubricants
  1. Graphite, molybdenum-disulphide, etc

• Emulsions
  1. Oil in water type - Cutting emulsions
  2. Water in oil type - Cooling liquids

Applications:

Silicone lubricants such as silicone oils are used as flow and gloss improvers in the paint industry. Semi-solid lubricants are used for lubricating some automotive components. Solid lubricants are used in air compressors and food processing equipments.