Rotating and sliding parts, which make contact with other parts, are subjected to wear due to friction. Viscous oil called lubricant is applied to these parts to avoid direct contact between them. The process of reducing friction is called lubrication.
Applying oil or grease to the axle shaft of the bullock cart and the cycle wheel, gearbox of automobiles, motor shafts of pumps, fans and sewing machine are some examples of lubrication.
Friction occurs as the shafts are rotating and the sliding parts moving on each other. It generates heat and the parts get damaged.
In order to keep the machine tools accurate and durable, it is necessary to apply lubricants between mating parts. It will reduce friction and wear is minimized.
Lubrication is the nerve centre of machine tool. As it is blood circulation for the human body, lubrication is for the machine tools.
The machine parts which need to be lubricated
1. Mechanisms of hydraulic systems
2. Guideways and sliding parts
3. Rotating shafts
4. Gear box
5. Feed box
6. Speed changing mechanisms
Objectives of lubrication
1. Smooth functioning of sliding and moving parts
2. To reduce friction and consequent wear
3. To remove burrs and dust
4. To reduce the heat generated due to friction
5. To prevent rust formation on precise parts
6. To provide cushioning effect to the load shocks
7. For hydraulic circuits to transmit power
Types of lubricants
The materials used for reducing wear between moving and sliding parts are called lubricants. Though there are many types of lubricants available, oil and grease are mostly used.
Grease is manufactured with the ingredients of soap and mineral oils. Different types of grease are manufactured for specific applications under different commercial names. So, it is necessary to know the specific type of grease to be applied for the specific part.