Why Lubricants are Needed, What are its Functions

When we come across a machinery operation and use it for physical activities. Its mechanical parts surface move, slide or roll against each other. Due to mutual rubbing of one part against another, always a resistance created to their movement. We call this phenomenon as friction. Friction causes wear and tear of surfaces of moving parts and a large amount of energy dissipates. Mechanical energy converts into heat due to friction between the moving parts. This effect decreases the efficiency of machines in terms of lifespan. Even increase fuel consumption to run the machine against friction.

In most case, these moving parts get heated up and lead to two surfaces welding. The main reason for this is that surface temperature rises to their melting point. This problem has a solution that if minute contacts of the surfaces in machinery can be cooled. Effectively decrease the heat generation due to friction by smoothing the surfaces. By introducing, a thin film of substance that can absorb the heat and flow the surfaces mechanically maintained in the normal state.

Thus, lubrication has come into the picture for the reason of smoothening the surface and to remove the heat by friction. The lubricant is a substance used for lubrication of surfaces. It would be named to any material whether it is solid or liquid when applied in between moving or sliding surface to protect them. The best lubricants have one purpose, to decrease friction between surfaces and withstand the condition of operations.

Its functions can be listed as:

  • It reduces surface deformation, tear and wear because the direct contact between the rubbing surfaces is avoided.
  • It reduces waste of energy so that efficiency of the machine is improved.
  • The expansion of metal at local points can be reduced.
  • Since it minimizes the liberation of friction heat seizure can be avoided at moving parts.
  • Running and maintains cost of the machine can be reduced.
  • Its main function in cylinders and piston engine as it acts as a seal.

Synthetic lubricants and their characteristics:

Synthetic lubricants are modified and chemical structure developed materials. They belong to the modern classifications of lubricant products. Synthetic lubricants are manufactured by reacting different chemical compound (silicon, chlorine, fluorine to esters and ethers) to attain novel properties. They designed and developed for unique applications where the mineral oils cannot withstand or perform effectively. For example, space vehicles and deep-sea explorations. Along with the development of new machinery and equipment, the demand for specific application lubricants increased in the market. New synthetic lubricants manufactured using the nanotechnology to perform multitasks to improve the life of the machine.
Important types of synthetic lubricants:

  • Polymerized CH compounds
  • F-C compounds
  • Silicones
  • Organic amines
  • Polyglycols

Essential synthetic lubricant characteristics:

  • Inflammability
  • Chemical stability
  • Higher flash point
  • Thermal stability at high operating conditions
  • Viscosity index

Selection of Lubricants for Cutting Tools:

After completion of the metal objects machine drawing. The required cutting tools for drilling, tapping, surface removing of metal etc are selected to perform the task. The machining process uses high-quality cutting tools. The cutting operation itself possesses generation of heat and wears of metal along with them the aspect of product finishing. Ceramics, carbon steel, high-speed steel, cemented carbides and cubic boron nitride used as the materials of cutting tools. They selected based on the temperature of cutting operation and hardness of the object parts.

Engineering solution has brought up the idea of utilizing lubricants during cutting. This idea improved the lifespan of the cutting tools and made it possible to perform the operation in safe conditions. Lubricant if flushed continuously between the cutting tool and the object surface of contact. It absorbs the heat from the surface of the tool and the object. This prevents damage to the material structure during cutting. With lubrication, metal wear effectively reduces and enhance the smooth operation to decrease the power consumption. Even noise hazard drastically decreases.
Features to be considered for the selection of lubricants for cutting tools:

  • It should be non-toxic.
  • It should be free from CFC’s
  • Colourless
  • Anti-foaming
  • Non-sticky
  • No residue formation
The function of Lubricants in a Transformer:

Oil-filled transformers installations in the cities are increasing to fulfil the demand for power. In this situation, effective and efficient working transformers are required for the engineers to distribute the power without loss and interruption.  Without lubricants, the transformer does not operate and it is not the complete design. Lubricants perform insulation and cooling by heat transfer in the transformer.

Most used transformer oil:

  • Organic esters
  • Naphthenic content mineral oils

Properties required for transformer oil:

  • Dielectric property
  • Inflammable
  • Biodegradability
  • Viscosity
  • Breakdown
  • Voltage
  • Moisture
  • Pour point
  • Oxidation stability
  • Non-corrosive
  • Density

 Heat transfer function of lubricants in a transformer

  • Heat recovery
  • Insulation

Risk due to wrong lubricants utilization

  • Fire accidents
  • Non-biodegradable environmental pollution
Application of Lubricants in Various Fields:

The primary application of lubricants is to reduce friction, dissipate heat due to friction quickly to the surroundings to improve the performance of moving parts machinery. Lubricants are one of the primary objectives of tribology concept.

Automobile and machinery:

  • Piston and cylinder engine systems,
  • Gears and chains for wire rope lubrication system,
  • Rotating shafts and ball bearings of pumping and compression systems

Drilling and cutting works:

  • Lubrication of drill bit by lubricating to transfer the heat caused by abrasion of the bit surface and rock

Lubrication used by human external and medical applications:

  • Female lubricants
  • Lubricated condoms
  • Spermicidal lubricant
  • Hydration lubrication

Electrical equipments

  • Transformer oil
  • Transmission (insulation and conduction)

Types of lubricants:

  • Lubricant oil
  • Silicone lubricant
  • Water-based lubricant (friendly to the environment)
  • Grease lubricant
  • Natural lubricant
  • Spray lubricant
  • Engine lubricants
  • Food grade lubricants (Lubricants used by the food process industry and medicinal drug manufacturing industries)

Varieties of lubricants available:

  • Lubricating Jelly
  • Mobil Lubricants
  • Graphite Lubricant
  • Dry Lubricant

Lubrication system well established:

  • Centralized lubrication system
  • Automatic grease lubrication system
  • Farval lubrication systems
  • Mist lubrication system
  • Vogel lubrication systems
  • Auto lubrication system
  • Pressure lubrication system

Lubricants developments application by Nanotechnology:
Medical field:

  • Hydration lubrication mechanism thus offers great promise for medical and biomedical applications

Automobile and machinery field:

  • Lubricant oil dispersed with nano-particles of Copper and TiO2 increase the fuel economy of four-stroke engine.
  • Diamond-like carbon films superior corrosion and wear resistance and excellent low friction material.

Space field:

  • Carbon-based solid-liquid films as protective coatings to improve and sustain the space vehicle (machinery) in harsh space conditions
  • Diamond-like carbon films to protect moving parts for satellites and spacecraft due to erratic temperatures conditions.

Drilling and cutting field:

  • Extended reach drilling systems use polymer beads reduces friction between the drill bite and well surface.
  • Boundary lubrication with water-soluble nano-graphite.

Lubricant additives:

  • Lithium-based ionic liquids (conductive lubricating greases)
  • dicarboxylic acid esters