Every smooth surface has some irregularities in the form of depression and projections. These depressions and projections gets interlocked when two surfaces come in contact. This interlocking will developed resistance, which opposes the motion of one surface over the other. The resistive force is known as force of friction or simply friction. The friction always acts in a direction opposite to that of motion.
The force of friction between the moving surfaces results in abrasive action which results in wearing of surface. It is necessary to keep the moving surfaces separate from each other to prevent wearing. To separate the surfaces, lubricant is introduced between them. This process is known as lubrication. For effective lubrication, the film formed by lubricant should be thick and continuous. The formation of fluid film depends upon the viscosity and oiliness of the lubricant. More the viscosity, more will be the load under which lubricant will maintain a continuous film in between the moving surfaces.
Functions of Lubrication:
Lubrication is done to fulfill the following purposes.
- Lubrication reduces wear and tear between the two moving surfaces and thus results in saving of power consumption.
- It helps in carrying away the heat generated due to friction and keep the bearings within the prescribed temperature ranges.
- It prevents the surfaces from corrosion, rust and dust and thus also acts as a cleaning agent.
- It reduces the vibration introduced due to rotating and reciprocating parts. This reduces the noise produced by bearings and other engine parts.
- Proper and timely lubrication of machine parts help in ensuring longer life and safe working of various machine parts.
- Lubricants also acts as sealing agent between the moving surfaces. For example – piston moving in a cylinder.
For effective and efficient working of various rotating and reciprocating parts of a machine, right quantity of lubrication is required at right time.