**3. Application methods**

After the selection of a suitable lubricant, its application method i.e. its delivery to the mechanical components such as gears, bearings, cams, tappets, chains, guideways and couplings of a machine or engine in correct quantity is considered. Liquid lubricants are applied to the machine elements by two methods. First type is called 'all loss method' while second type is called 'reuse method' [2]. In all loss method a small quantity of lubricant is applied periodically and the lubricant after use, gradually leaks away to waste. In reuse method, elaborate lubricating systems are designed to feed the required quantity of lubricant to various machine elements of the system. The lubricant after leaving the machine components is collected, cooled then filtered and recirculated to lubricate the machine components again. Most open gears, ropes, guideways, chains and rolling element bearings (except sealed for life rolling element bearings) are lubricated by all loss method. Nearly all grease lubricated elements also are lubricated by this method. Some devices used for all loss lubrication method include hand-held oiling device, grease gun, drop feed cups, wick feed cups, wick oilers, pad oilers, mechanical force feed lubricators, airline oilers and automatic or semiautomatic spray units. Reuse method of lubricant application has the oil circulating through a network of pipes that is pressurized by a pump or aided by gravity. However, closed oil sump systems employ splash oiling, bath oiling or ring oiling methods. Centralized lubricant application systems can reduce the quantity of lubricant usage as well as labour costs. Automobiles use an oil mist lubrication system to lubricate various machine elements of the engine and drive train. Considerations with regards to the lubricant characteristics and composition are required while designing a compatible system. Oil condition monitoring and routine checks are vital for the longevity of the machine elements lubricated by any method.

Solid lubricants on the other hand are applied as powder dispersed in a liquid lubricant or in a solid phase matrix. They can be also applied as a thin film coating. The coatings are made by various methods such as dip coating, thermal spraying, and cold. More robust ways of coating includes chemical vapor deposition or physical vapor deposition methods. Electrochemical processes are used for producing coatings of polymer-based solid lubricants and their composites.

**181**

**5. Future trends**

*Lubricant and Lubricant Additives*

**Physical and chemical characteristics**

**4. Lubricant analysis**

*Evaluation techniques and testing.*

Sulphated Ash Viscosity Volatility

**Table 2.**

Lubricant analysis primarily refers to the characterization and evaluation of the lubricant for various physical, chemical and performance properties in all stages of its life cycle. For solid lubricants and coatings, the analysis includes determining the composition and structure by using a range of spectroscopic and microscopic observation methods as well as measuring the coating consistency and thickness applying non-destructive evaluation techniques. Standardized tribological lab tests are used to evaluate their performance. Once a candidate material is identified,

For liquid lubricants, characterization is done to a much larger extent due to the large variety of applications and the implication of chemistry of the formulated oils on the machine elements performance and the overall performance of the entire equipment/machine or engine. The lubricant analysis can be classified as physical and chemical characteristics evaluation, Performance test evaluation and Engine Test evaluation as summarized in **Table 2** [2]. Additionally, end users also develop their in-house in-service lubricant analysis to monitor and maintain the condition of the lubricant. The objective of such analysis is to ensure optimum performance, achieve expected life of the equipment as well as the lubricant flowing through it.

Current automotive lubricants are optimized for internal combustion engines and drive trains. Electric vehicles (EVs) which use electric motors possess new challenges of lubrication such as high-power density of the small gear box which require efficient cooling. Hydro lubricants and synthetic gear oils are excellent candidates for such application but may pose sealing issues which requires innovative solutions. Lubricants are also required in the rolling element bearings of EVs that must stop electro-erosion

larger-scale bench testing, such as engine tests, are conducted.

*DOI: http://dx.doi.org/10.5772/intechopen.93830*

Flash point Corrosion and Rust

Total Acid Number Emulsion and Demulsibility Test

**Performance test evaluation**

Protection Test

Pour Point Fuel Economy

Color Oxidation Tests Oxidation stability and bearing corrosion

Density and API gravity Thermal Stability Single cylinder high Temperature tests Carbon Residue Foaming Tests Multi cylinder high temperature tests

Neutralization Number EP and Antiwear Test Rust and corrosion protection tests

Total Base Number Emission and protection of emission

**Engine test evaluation**

Multi cylinder low temperature tests

Oil Consumption rates and volatility

protection

control systems


#### **Table 2.**

*Tribology in Materials and Manufacturing - Wear, Friction and Lubrication*

been filled [15].

by moisture content [16].

**3. Application methods**

lubricated by any method.

entrained into tribological contacts.

*2.4.3 MoS2*

friction reduction. Graphite has hexagonal crystal structure which has the intrinsic property of easy shear. DLC exhibits high hardness and low friction due to an amorphous structure that combines graphitic and diamond phases. They can be doped with hydrogen or nitrogen for achieving desirable properties. Recently, a series of patents on superlubricity of nano-diamonds and graphene films have

Molybdenum disulphide are transition-metal dichalcogenides like Tungsten disulphide (WS2) work on the mechanism of interlamellar shear between covalently bonded hexagonal basal planes like that of graphite. Their performance is affected

Apart from the advantages mentioned earlier, solid lubricants also have a few disadvantages. They have less ability to carry away heat and contaminants away from the contact. They have poor self-healing properties, and they are not easily

After the selection of a suitable lubricant, its application method i.e. its delivery

Solid lubricants on the other hand are applied as powder dispersed in a liquid lubricant or in a solid phase matrix. They can be also applied as a thin film coating. The coatings are made by various methods such as dip coating, thermal spraying, and cold. More robust ways of coating includes chemical vapor deposition or physical vapor deposition methods. Electrochemical processes are used for producing

coatings of polymer-based solid lubricants and their composites.

to the mechanical components such as gears, bearings, cams, tappets, chains, guideways and couplings of a machine or engine in correct quantity is considered. Liquid lubricants are applied to the machine elements by two methods. First type is called 'all loss method' while second type is called 'reuse method' [2]. In all loss method a small quantity of lubricant is applied periodically and the lubricant after use, gradually leaks away to waste. In reuse method, elaborate lubricating systems are designed to feed the required quantity of lubricant to various machine elements of the system. The lubricant after leaving the machine components is collected, cooled then filtered and recirculated to lubricate the machine components again. Most open gears, ropes, guideways, chains and rolling element bearings (except sealed for life rolling element bearings) are lubricated by all loss method. Nearly all grease lubricated elements also are lubricated by this method. Some devices used for all loss lubrication method include hand-held oiling device, grease gun, drop feed cups, wick feed cups, wick oilers, pad oilers, mechanical force feed lubricators, airline oilers and automatic or semiautomatic spray units. Reuse method of lubricant application has the oil circulating through a network of pipes that is pressurized by a pump or aided by gravity. However, closed oil sump systems employ splash oiling, bath oiling or ring oiling methods. Centralized lubricant application systems can reduce the quantity of lubricant usage as well as labour costs. Automobiles use an oil mist lubrication system to lubricate various machine elements of the engine and drive train. Considerations with regards to the lubricant characteristics and composition are required while designing a compatible system. Oil condition monitoring and routine checks are vital for the longevity of the machine elements

**180**

*Evaluation techniques and testing.*
