Like any greases & oils, Lubricants are usually used to reduce the effect (heat generated when the surface moves) of friction. Thus, we can say that it decreases the friction between surfaces in mutual contact rather than increasing friction. Therefore, a good lubricant or proper lubrication process reduces friction and has multi-functional tasks mentioned below.
- 1st & for most lubricants used to separate or lubricate two moving surfaces.
- 2nd A good lubricant or if you have selected proper lubrication process then lubricants can be a good sealant & can be used for the sealing process.
- 3rd one of the major roles of lubricants is to reduce the heat generated by two moving surfaces in mutual contact. Lubricants can act as a coolant.
- Last but not least Lubricating oils & greases can also protect the material from different types of foreign particles, which can damage the materials like bearing, gears etc. & protects from oxidization and corrosion.
To clarify how lubricants decrease friction & reduce friction-related issues, you may expand your knowledge base by reading our article Relation between Frictions, Wear & Lubricants. Also, we have discussed the major difference between Lubricating greases & lubricating oils & how you can select industrial oils or industrial greases for different types of application lubrication processes. The whole system of friction & its different types of effects & reducing it through proper lubricants selection & lubrication process is called Tribosystem (Tribological System).
Suppose you want to know the Tribosystem of different types of industries. In that case, you can check from the Industry tab mentioned on our home page of the website & you can check the different applications lubrication process of Steel industry directly from here.
A proper Tribological system is required to increase the overall performance & application life & this results in longer life of industrial components, less energy input (Sustainability) &, finally, cost savings. To choose the right lubricants & proper lubrication process for any application, it is necessary to understand the application circumstances & influences. Suppose we need to understand the application circumstances & influences. In that case, we have to understand the Base body & Antibody material characteristics, Wear characteristics, duration, load, temperature, surface roughness, pressure, speed etc. If you have not considered all these factors before selecting lubricants, improper lubrication can increase friction effects like temperature & application failure rate.
Tribological point of view there are different types of friction are there:-
Table of Contents
- Sliding Friction
- Rolling Friction
- Boring Friction
- Sliding & Rolling Friction
In addition, there are many effects or consequences happened due to frictions:-
- Extreme Vibrations,
- Heavy Noise
- Heavy Heat Generation
- Wear & Material Transfer
- Geometry changes of the material due to above mentioned reasons.
To reduce different types of frictions & friction-related issues, Lubricants are coming to the picture. In the modern industry 4.0 (Smart factory) era, a couple of specialty lubricants manufacturers consider themselves specialty lubricants manufacturers. Therefore, what are the properties good lubricants should have to consider these lubricants a good or specialty lubricants as per application point of view.
Properties of lubricants
Lubricants will be considered good or high-quality & specialty lubricant if a lubricant normally possess the following properties:
- Lubricants should have High boiling point.
- In addition Lubricating Grease or Lubricating Oils should have Low freezing point
- High viscosity index of any industrial lubricants is better to use high temperature or high loaded applications. Normally Synthetic oils & synthetic greases have high viscosity index compare to mineral-based gear oils & greases.
- Thermal stability is also one of the major criterial during selection of a good lubricant. Thermal stability confirms that the lubricant will not lose its property if used in high temperature application.
- Hydraulic stability is also considered a good property of any industrial lubricant.
- A good lubricant should have good Demulsibility property. This is the property, which confirms that how oil will be separate from water. Oil & water is naturally separate because of their molecular property. Oil sticks with oil & water molecules stick with water. However, some time, the oil used in some special applications like turbine, there are huge chances of mixing oil & water. That time demulsibility property appears. A good demulsibility property greases or oils will not mix with water.
- Prevention of corrosion is most likely we all know what the meaning of it is & as we have mentioned earlier in this article that lubricants should have good sealing property, by which lubricants will be able to prevent corrosion of material.
- High resistance to oxidation is also a major criteria of good industrial lubricants.
We have already discussed about the Lubricants working principle & what are the properties should have in a good industrial lubricant. As a meaning of industrial lubricants, we understand Industrial Lubricating Greases or Industrial Lubricating Oils but now its turn to understand different types of lubricants available in the smart market of Industry 4.0.
Different types of Lubricants available for different types of industry & applications:-
- Solid Lubricants also known as dry lubricantsPolymers
- Metal Solid
- Carbon & Graphite
- Ceramic & cermet
- Semi solid lubricants, usually known as grease.
- Liquid Lubricants.
- Gas Lubricants
Solid Lubricants or Dry Lubricants:-
Dry lubricants or solid lubricants are those types of lubricants available in the smart industry of 4.0, despite being in the solid phase; they are able to reduce friction between two sliding surfaces sliding against each other without any usage of any types of liquid oil medium. There are two main dry lubricants are generally found in most of the industry is graphite and molybdenum disulfide (MoS2).
Polymers are one of the lubricants, which comes under largest group of solid lubricants. They are very much suitable for the application with low loads and in addition to that, these types of lubricants have a lower thermal conductivity. Polymers and polymer-based composites are becoming preferred materials and coatings for green tribology in the modern era of sustainable lubrication because of the combination of good mechanical and tribological properties, resistance to corrosion and chemicals, reduced noise and maintenance costs. There are mainly three types of polymer solid lubricants are available.
- Polytetrafluoroethylene (PTFE),
- Synthetic polymers.
Metal Solid Lubricants
This type of Solid lubricants are critically important for safe and smooth operations of numerous tribologic systems. This type of Metal solid lubricant is a material used as powder or thin film & contain lamellar solids and achieve low friction through a process called film transfer. Molybdenum disulfide (MoS2) is the most commonly used metal-solid lubricant. Some of the advantages of metal-solid lubricants are a high load carrying capacity, good high-temperature resistance, and low friction. One of the major benefit of this type of lubricants are It can also stay stable in vacuum up to 1000 degrees Celsius. Hence, molybdenum disulfide also used in different types of space high temperature applications.
Carbon & Graphite
Graphite is one of three allotropic forms of the chemical element carbon; the other two are diamond and amorphous carbon. Graphite shows lower shearing strength under friction force. Thus, it can be used as a solid lubricant and has become one of traditional and primary solid lubrication materials.
In addition, carbon graphite seals are used as solid lubricants. They have desirable properties such as high-temperature stability, high oxidation stability, and sustainable performance in high sliding speed applications. Graphite as a material has low friction and can withstand moderate loads. However, if we use graphite as a lubricant we need to check the temperature does not exceed beyond 500 degrees Celsius because the lubrication performance of graphite actually increases with an increase in temperature but after 500 degrees Celsius, the incidence of corrosion also increases.
Ceramic & Cermet
Ceramic and cermet can be used, as a lubricant when it is used as coatings where a lower wear rate is more important rather low friction. Ceramic or cermet coatings performance is good at high-temperature ranges of around 1000 degrees Celsius. An only 0.5mm thick coating of ceramic or cermet material can offer a low-cost way of reduce wear of the material.
Semi solid lubricants, usually known as grease
Now it’s the turn of greases & this type of semi solid lubricants are the versatile lubricants usually used in mostly every type of industry for reduce the friction & issues due to friction. There are different types of greases available in the market as per the application point of view. Lubricating greases are known as versatile lubricant because it can be used in dry or wet environment, dusty or clean environment, or even corrosive environment.
Greases are Non-Newtonian fluids with high viscosity at low shear rates and low viscosity at high shear rates. One of the most significant properties of grease is consistency. Consistency is nothing but the relative hardness or softness of any material. Actually greases are non-other than lubricating oils + Thickeners + Additive packages. You can read more about the difference between Lubricating Oil & Lubricating grease here.
Different types of Lubricating oils are known as Liquid Lubricants & most common lubricants usually used in High temperature, High load, and high speed. Lubricating oils are normally made by adding Base Oil + Additives + Solid Lubricants. There are different types of Lubricating oils are available in the market.
- Mineral oil
- Synthetic Oil.
- Vegetable oil
- Animal oil
Mineral-based lubricants are extracted from crude oil. Mineral oil lubricants can differentiate as per oil properties.
- Paraffinic oil
- Naphthenic oil
- Multigrade oil.
In addition, there are different types of Synthetic oils used in different types of applications mostly in gearbox as per the application requirement & environmental conditions.
- Synthetic hydrocarbon (SHC), Poly-alpha-olefin (PAO).
- Perfluorinated polyether (PFPE).
As per the different service temperature, range different types of lubricating oils are used.
Oil-based lubricant made from rapeseed and castor is known as vegetable oil lubricant. Vegetable oil lubricant is less stable than mineral oil lubricant at high-temperature ranges.
Fats extracted from fish and animals are the sources of animal oil. Sometimes It is added to another types of mineral based oil to improve the film forming ability of the mineral oil. However, in modern technological market, animal oils are not used for any application & not available in the market.
Nitrogen gas and helium gas are used as gas lubricants where film thickness requirement is ultra small. The main advantages of using gas lubricants are it can be used very wide temperature range, also these types of lubricants used where no sealing is required for lubrication. Some benefits of Gas lubricants are – very low friction due to low viscosity, no vaporization, no solidification, and no decomposition.
The major dis benefit of using gas lubricants are low load carrying capacity & require very specialist design engineer to design the applications where gas lubricants will be used.
Final Words Can Lubricants Increase Friction
Lubricants cannot increase friction between two moving surfaces but if you have not chosen right lubricants for right application or if you have, chosen high viscosity grease or oil in high speed & low load carrying applications, then it can increase the friction between internal molecules of the lubricants & thus lubricant can increase the overall temperature of the application. As we have already discussed in this article that reducing temperature of the application is one of the most important criteria of a proper lubricant but by choosing wrong viscosity lubricant, Lubricants can increase the temperature which is also a major effect of friction. Normally due to friction, temperature increases & we use lubricants to reduce temperature.
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