A lubricant is a substance introduced to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. It may also have the function of transmitting forces, transporting foreign particles, or heating or cooling the surfaces. The property of reducing friction is known as lubricity. Typically, lubricants contain 90% base oil (most often petroleum fractions, called mineral oils) with less than 10% additives. Vegetable oils or synthetic liquids such as hydrogenated polyolefin, esters, silicones, fluorocarbons and many others are sometimes used as base oils. Additives deliver reduced friction and wear, increased viscosity, improved viscosity index, resistance to corrosion and oxidation, aging or contamination, etc. Non-liquid lubricants include grease, powders (dry graphite, PTFE, molybdenum disulfide, tungsten disulfide, etc.). Dry lubricants such as graphite, molybdenum disulfide and tungsten disulfide also offer lubrication at operating temperatures (up to 350°C) higher than liquid and oil-based lubricants. Limited interest has
The lubrication mechanisms that occur at the tool–workpiece interface for the transition and expansion zones are discussed. Suitable lubrication systems for the transition and expansion zones are reviewed based on the mechanics of deformation and material flow at the interface. Details of two model tests for evaluating the performance of tube hydroforming (THF) lubricants and die coatings are given. The optimization of die geometries for the model tests is based on sensitivity analysis through the finite element method together with experimental verification. The details of these tests are given and their development is discussed.
It was observed in preceding sections that the mean frictional force and wear coefficients were high at low temperatures. Whereas at high temperatures, the mean of frictional force and wear coefficient was found to be low. Similarly, at low loads, the mean frictional force was low and the wear coefficient was high. As the load increases, the mean frictional force increases slightly, but the mean wear coefficient decreases significantly. With an increase in load, the mean value of the wear coefficient decreases. A thorough investigation of the SEM images is needed to evaluate the friction and wear characteristics. In the SEM images, bright patches were found in between the smooth regions. These bright patches were the mechanically developed oxide film formed on the specimen surface during the sliding motion. The mechanically formed oxide layer protects the specimen from severe wear and thereby improves the lubrication between the sliding surfaces in solid lubricants.
Another criterion used to rank the lubricants was the dif- ference in the PHs attained, i.e. the higher the PH, the better the lubricant. Fig. 7 shows the PHs attained for all lubricants. All the tests were conducted using the pressure-loading path shown in Fig. 5, where a maximum pressure of 570 bar was attained. As can be observed in Fig. 7, Lub A re- sulted in a PH of 72 mm followed by Lub D with a PH of 71.5 mm. These results show a similar trend as that observed in wall thickness distribution (Fig. 6). Based on the PH, the lubricant performance can be ranked as shown below.
Eswaraiah et al.  studied the tribological properties of graphene as the antiwear, antifriction and extreme pressure additive in the engine oil. It was reported that there is an enhancement in all the three above-mentioned properties, attributed to the ball bearing lubrication mechanism by the nano-particles. Maleque et al. [126,127] experimentally studied the tribological behavior of palm oil methyl ester blended lubricant for steel cast iron tribopair for cylinder liner piston ring assembly. It was reported that the corrosion wear and pit are the main reason for the wear on the mating surfaces. It was observed that more than 5 % of the palm oil methyl ester in the lubricant causes oxidation and corrosion. Zulkifi et al.  studied the tribological behavior of Palm oil based trimethylpropane (TMP) esters, as an engine lubricant. Four-ball tester configuration was used for a boundary, hydrodynamic, elastic- hydrodynamics lubrication regimes. The blended lubricant consists of (5, 10, 15, 20 and 100 %) palm oil TMP ester. It was reported that the lubricant oil with palm oil TMP ester gives better performance as compared to the ordinary oil. Bekal et al.  studied the behavior of the Pongamia oil as the alternative for the mineral oil for the Internal Combustion Engine (ICE) application. In their study, three oil samples are prepared i.e. pure Pongamia oil, pure mineral oil and a blend of both the oils. Their samples were tested on the commercial four strokes, single cylinder, direct injection diesel engine. It was reported that in the Pongamia oil lubricant friction losses were less and it eliminates the emission of metal traces unlike in the mineral oil lubricant. Bhale et al.  studied the wear characteristics of a cylinder liner rings with diesel and biodiesel on a pin on disc tribometer. The pins and the disc are prepared from the actual cylinder liner and the top ring of the
Powder flow is critical during tableting as it must flow easily and uniformly into the tablet dies to ensure tablet weight uniformity and production of tablets with consistent and reproducible properties (Fassihi and Kanfer, 1986; Tan and Newton, 1990; Sandler et al., 2010). Powder flows when gravitational forces become higher than the friction and cohesion forces that influence particle-particle interactions. Cohesive forces refer to the attraction between particles and include van der Waals’ forces, capillary forces and electrostatic forces. Cohesive forces are affected by the surface properties of the particles. As boundary layer lubricants form a film around particles, these lubricants affect the cohesive forces thereby also affecting powder flow. Furthermore, friction is also affected by the surface properties of the particles. Friction acts at contact points between particles; thus, surface morphology affects friction forces. If the contact area is increased, the potential contact points are increased, thus increasing friction. Boundary layer lubricants reduce friction by reducing surface irregularities, reducing contact points between particles, and thus friction forces
Widely used test equipment is often used to test the performance of lubricants. Usually, these tests are carried out using standard test parameters (standardized tests according to DIN, ASTM and many other standards) which have no significant correlation with the parameters from practice. Often a wrong system analysis is to blame. Test results obtained from tribometer tests should be taken with caution and must be justified with field tests . Furthermore, various apparatuses provide completely different results, e.g., through different engagement conditions, movements, lubrication conditions, temperatures, loads, etc. 
The static friction coefficient is related to many factors including materials properties, topography, applied load and environmental conditions including temperature, humidity and lubrications. On the other hand, the increase of temperature was found to cause reduction of stiction for mechanically textured media due to change of lubricant properties (Habib S. Benabdallah et al.,2006). Lubrication can also describes as the phenomenon such reduction of wear occurs without human disurbance. There are useful lubricants that can give best protection to the reducing wear and friction generated from sliding between two contact surface.
The main difference between man-made and natural lubricants is that the former are usually “oil-based” while the latter are “water-based” systems. Use of water for lubrication, instead of oil, has many benefits (most notably environmental) and nature is a great tutor to show us how to reach this. In the field of effective natural lubrication, one of the most striking examples of the possibility for bioinspiration is the inspiration from the lubrication of mammalian joints. The effective lubrication in this system is expressed by the low friction which is found to be in range of 0.002-0.006. Considering the low speeds involved, this friction is much lower than would be expected using existing technologies. To illustrate this difference, Figure 1 shows the friction values reached in mammalian joints compared to the friction values that are reached in tribological systems (e.g. in the internal combustion engine).
Lubricants are satisfactory for low-speed and low-pressure applications. Boundary lubrication occurs when oil viscosity is insufficient to prevent surface contact. Anti-wear additives provide a defensive film at contact surfaces to reduce wear. Anti-wear property is identified by standard laboratory tests. Vegetable oil-based bio lubricants have better anti-wear properties than mineral oils. These are the essential properties of bio lubricants which should posses to perform as good lubrication. C. Benefits of Bio Lubricants
For the lubrication study, we utilise the G50 starch polymers extracted from dissolution in 65/35 solvent mixture where there is equal proportion of dissolved amylose and amylopectin. Lubricants are produced by adding either water or EMIMAc to the 65/35 supernatant (after centrifugation) that contains the solubilised species to investigate how they affect lubrication under different solution environments (solvent ratio), which is expected to influence the conformation of the polymers and their adsorption to PDMS surfaces. In addition, the 65/35 solvent mixture is also used to extract leachable material from waxy maize starch (WMS), which contains predominantly amylopectin. From this preparation, 0.25 and 0.33 wt% starch solutions are prepared. WMS showed high solubility in 65/35 and desired concentrations were achieved using only 0.5 wt% of WMS suspension.
Fluorogenic lubricants are synthetic lubricants containing fluorine elements, the most important of which are perfluorocarbon hydrocarbons, fluorochlorocarbon hydrocarbons and PFPE. PFPE is a synthetic polymer because the molecules do not contain hydrogen, so it has strong oxidation resistance, good lubrication properties, and good viscosity temperature properties along with a low freezing point. In addition, PFPE products have a high boiling point, so the evaporation loss is small; at normal temperature, it is a liquid and has been used as a space machine lubricant for more than 40 years [92– 95]. All reported PFPE structures are linear, as shown in Figure 4.
Amit Suhane, et al,  studied in this paper represents the tribological investigation of mahua based oil lubricants for mechanical tribological properties. Mahua oil is blended with conventional gear oil (90T) in different ratios. Tribo pair used is plain carbon steel cylindrical pin and mild steel disc. 90T Oil is blended with mahua oil in prepositions varying from 5%-25% by volume. Total five blends have been prepared. The plain carbon steel pin used is cylindrical in shape and is tested against the circular mild steel disc. Pin dimension used is 30mm x 6 mm, whereas disc dimension is 160mm x 8mm.Pin and disc material has carbon % (0.20- 0.35) and (0.40-0.55%) respectively. POD machines is used for measuring wear characteristics at varying speeds of 60 to 600 RPM. The test load is 10 N and the disc is rotated at 100 RPM for duration of 30 Minutes further tests are carried out at higher load and speeds. Five blends are prepared in the ratio varies from 5 to 25.,the result shows that specific wear for given loadings and speed for all the oil samples more or less are increasing and reportedly in the range of 0.000064 mm3/Nm to 0.001792 mm3/Nm. Coefficient of friction values reported during experimentation in the range of 0.014 to 0.03 clearly suggests the regime at contact zone to be boundary lubrication. Worn out surface of pins suggests pronounced abrasive and adhesive wear pattern under prevailed boundary film lubricated conditions. The observations from the experimentations suggests that addition of 5-10% mahua oil in the 90T oil has good wear reducing traits for maintenance purpose at different operating conditions.
Non-Newtonian lubricants are commonly found in engineering. Here we illustrate the utility of a derivation of a Reynolds-type equation from a variational functional. The technique developed can be readily applied to any other lubrication problems, and the present paper can be used as a paradigm for the establishment of a Reynolds-type equation for various lubrication problems.
Nanoindenter-based scratch tests are simple, rapid, and reliable method to evalu- ate the tribological properties of materials at the microscale. It not only works well on dry polymer surfaces, but also can evaluate thin fluid film lubrication on polymer surfaces. By using different experimental tips (different shape and radius) on the same polymer surfaces, different coefficient of friction results are obtained. Because of the different molecular structures, different polymer surfaces show different tribo- logical properties. Furthermore, the relationship between the adsorption of lubricant and the lubricity of lubricant has been studied. Lubrication is an extremely complex phenomenon and it can be influenced dramatically by the lubricant, including the lubricants’ molecular weight, molecular structure (both its chemical structure and its geometry (et al., di-block versus tri-block) and chain length, the solvent, the sub- strates, including the substrates’ roughness and chemistry, the number of lubrication layers, the sliding velocity, and applied load. In addition, the lubrication properties of synovial fluid and its components (sodium hyaluronate (HA), proteins, and phos- pholipids) have also been studied. The concentration and molecular weight of sodium hyaluronate both have great effect on its lubricity. The concentrations of γ-globulins and albumin also have effect on their lubricating properties. With just one type of protein or with excessive proteins, the solutions looses lubricity. Addition of HA can improve the lubricating properties of some protein solutions. DPPC (dipalmitoyl phosphatidylcholine) also shows some lubricity for polyethylene. However, without HA, the concentration of DPPC has no effect on its lubricity at the microscale. Ad- dition of HA can improve the lubricity of DPPC solution when the concentration of DPPC is high. Depending on the concentration, every component has some lubricity, but working synergistically at the concentrations found in typical, healthy synovial fluid can greatly improve their lubricity. Indeed, the Synovial fluid model, which has γ-globulins at 7 mg/mL, albumin at 11 mg/mL, HA (MW: 2.0 MDa) at 3 mg/mL,
ABSTRACT: The Indian Textile Industry, though one of the oldest in India, has not given due importance to lubrication. Lubrication system is critical in many industries and it is equally important in the Textile Industry. The basic problem in the lubrication of Textile machinery is that the product comes into intimate contact with the machine parts and any contamination of the product or the lubricant cannot be tolerated. Present-day, textile machines are becoming more and more sophisticated and complex with the use of various types of drives, components moving at widely varying speeds and working under different loads. The new machines are designed with a view to work them at very high speeds over long periods without major break- down. Lubrication, therefore, is becoming more and more critical in maintaining both the efficiency and reliability of machines and thereby, the quality of the finished product. It has been observed and confirmed that a majority of the problems and breakdowns on machines occur due to faulty lubrication. With the establishment of mass production, quality consciousness among the buyers & the competitive market of textiles, keeping the overall production cost under the reasonable control, is need of time. This can be achieved only when the effective maintenance with lubrication is given prime importance. Effective performance of machine requires careful selection of lubrication system, the lubrication which gives long life to machine.
Lubricating grease is made from petroleum thick oil substance which is used as lubricant. The grease consists of oil and other lubricant that is mixed with a typically a soap, to form a semi solid. Lubricating grease contains some performance additives. Grease are a type of shear thinning fluid which define the viscosity of fluid is decreased under shear. The function of grease is that minimize the leakage as sealant. The features of grease is that posses a high initial viscosity, which depend on application of shear. The change in viscosity is called the Thixotropy. Lubricating grease is used in much industry to reduce the wear and friction between movable parts. Due to its semisolids character it act as seal thus preventing from leakage. The main difference between the automated and manual lubrication is that in the accordance of manually applied lubricants, mechanic tend to lubricate chart. There are many advantages of automation over manual application. It is better to apply small amounts of grease at small time rather than high amounts of grease at large time. With manual application, the device is to apply as large grease as possible without causing harm due to large greasing, thereby maximize the re-lubrication times.
Prospective of the lubrication industry seems to be introduction of new technology that meets the human health and eco-toxicity requirements. Special consideration is being given to bio-accumulation and biodegradation of lubricants in the environment. The new technology may create sustainable eco-friendly lubricants with properties that will lower friction and wear, thereby improving system efficiency ultimately conserving energy, a higher lubricity lending to lower friction losses and improved efficiency, affording more power output and better economy. With increasing oil prices and environmental awareness, the demand for renewable and sustainable lubricants increases. Funding of fundamental research is being improved to augment the macroscale development, economical competence, and industrial use of biolubricants for energy conservation and sustainability.
Faced with the current competitive business scenario, opportunities for increased efficiency and productivity capable of placing any industry at the level of excellence in the market are necessary. For example, production losses and costs are opportunities to standardize grease consumption in any industry in Brazil, as pointed out in the literature, through the analysis of its lubrication process. From this, three main critical lines were established through the Pareto Diagram and focused on all listed actions and root causes of the problem raised through the Ishikawa Diagram, which was used in this work to evaluate the use and consumption of grease. As the research unit, a renowned food industry was used. All proposed actions were implemented and tested to verify that no malfunctions would occur. Thus, an analysis of the current process, hitherto adopted, has opened the door to several opportunities that have led to recognition of the critical lines within the industry.
Today’s weaving preparatory machines give much faster production because of their high speed. Lubrication plays important role in maintenance of modern sizing machines. Good lubrication practices give high speed as well as high efficiency. The advancement in the environmental condition of industrial machinery working such as high temperature, high pressure and dynamic condition has demanded the new characteristically requirement of lubricant and their properties. The fluid lubricants are commonly used for reduction of wear, elimination of heat and corrosion etc.