What is a lubricant? | [Need, Properties and Types Explained]

By | December 3, 2021

What is a lubricant

A lubricant is a substance which is applied between two rubbing surfaces for reducing friction. While dealing with machines, friction among the machine parts can damage it severely.

lubricant
Lubrication

Problems caused by friction

  • It reduces machine parts life.
  • It increases overall power consumption. Because a considerable amount of power is used in overcoming friction.
  • Due to friction machine parts create noise and vibration, which is not good for any work place.
  • Friction cause overheating of components, due to rubbing.
  • Wear and corrosion of machine parts.

Objectives of Lubrication

  • To reduce friction forces between moving parts
  • To reduce wear and tear of moving parts
  • To cool the surfaces heated by the friction between moving parts
  • In some cases it is also used to seal the space between adjacent parts
  • In some cases it is also used to absorb shocks
  • To act as a cleaning agent

Properties of a good lubricant

  • It should have suitable viscosity.
  • It should act as protective covering against corrosion.
  • It should have heavy strength to prevent metal to metal contact under heavy load.
  • It should not chemically react with the machine parts.
  • It should have low pour point.
  • It should not react with air, water and fuel.
  • It should have cleaning ability.
  • It should be non toxic.
  • It should be non inflammable.
  • It should have non foaming characteristics.
  • Its viscosity should not change with temperature.
  • It should ensure the adherence between contacting surfaces.
  • Its flash point and fire points should be high.
  • It should not form deposits by reacting with the machine parts or the surrounding environment.
  • It should have low cost.

Types of lubricants

Basically there are two types of lubricants.

Oil and Grease.

Oil is used where

  • Oil are used where a simultaneous cooling is also required.
  • Oils are also used for machine parts where greasing is difficult.
  • Oils are used for low loads.
  • Oils are used for the machines which are using central lubrication systems.

Grease is used where

  • Load is high.
  • Used for a part of machine (not for whole machine).
  • Used for machine parts where frequency of lubrication is low (like bearings).

Image (also featured) attribution: By Audriusa – Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=7218733

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