Performance Of Solid Lubricants Research Articles

Effect of different chemical conversion coatings on the tribological performance of cylindrical thrust roller bearings under conditions of dry friction and solid lubrication

The chemical conversion coating technology, as a surface technique, can effectively reduce surface wear. In this study, the chemical conversion coating technique was implemented to acquire three distinct coating variations on the surface of cylindrical thrust roller bearings (CTRBs). Nanoindentation tests were conducted to analyze the mechanical features of the coatings, specifically targeting the elastic modulus and nanohardness. To evaluate the surface properties of the coatings, a 3D profilometer was employed. Moreover, the tribological behavior of the CTRBs, subsequent to the application of the coatings, was examined under conditions of dry friction and solid lubrication using a vertical friction and wear testing apparatus. A theoretical framework was established to elucidate the initial phase of transfer film spreading and determine the friction coefficient (COF). The impact of mechanical properties, surface characterization, and crystal structure of the coatings on the tribological performance, both under dry friction and polytetrafluoroethylene (PTFE) solid lubrication conditions, was thoroughly investigated. The findings revealed that, when subjected to dry friction, the dominant factor influencing the tribological performance of the coatings was surface roughness. The addition of solid lubricants can effectively improve the friction performance, resulting in a maximum reduction in bearing wear of 83.9 % and a minimum reduction of 13.0 %. By analyzing the worn surfaces and bearing vibration signals, the influence of coating characterization on the wear and anti-friction performance of solid lubricants is discussed.

Enhancing tribo-rheological performance of solid lubricants mixed bio-based emulsions applied through minimum quantity cooling lubrication technique

Enhancing tribo-rheological performance of solid lubricants mixed bio-based emulsions applied through minimum quantity cooling lubrication technique

Study the performance of solid lubricants during hard turning of AISI 4340 steel

Hard turning process is widely used in manufacturing industries. The main problem associated with hard turning is the high frictional heat generation. Traditionally cutting fluids are used to control the heat generation. However, the major drawback related with the use of cutting fluids is the environmental pollutions. The use of solid lubricants during machining is another alternative technique to control the heat generation. It is environmental as well operator friendly. Therefore, in this research work, an experimental study has been conducted to investigate the performance of solid lubricants assisted hard turning. The hexagonal boron nitride (h-BN) and zinc sulfide (ZnS) were taken as a solid lubricating medium. The cutting speed, feed rate, workpiece hardness and tool nose radius were selected as process parameters. The cutting force and chip tool interface temperature were taken as performance indicators. The experiments were performed by using central composite design. The significance of process parameters was analyzed by performing analysis of variance (ANOVA). The second order mathematical models of cutting force and chip tool interface temperature were formulated. The optimal value of the process parameters which provides minimum cutting force and chip tool interface temperature was suggested. The experimental results were compared with dry and wet conditions of machining. The results indicate that solid lubricants have shown better machining performance when compared to dry and wet conditions.

Experimental investigation to study the performance of solid lubricant during turning EN31 steel and Ti-6Al-4V alloy

In the present day manufacturing industry, achieving machining accuracy, high production rate, and high material removal rate and increasing tool cutting life is becoming more vital and challenging task. Machining of hard materials is difficult to carry out because of high temperature generation between tool-workpiece interface which results in significant reduction in surface quality, tool life and high wear rates of the cutting tools are experienced. The use of proper lubrication in machining processes is critically important to modify the conditions of contact area by effective control over frictional interaction which should ensure change in tool-chip interface and machining mechanics. This paper present some preliminary results on experimental studies on EN31 and Ti-6Al-4V alloy materials on NC lathe machining using TiN coated cutting tool. MoS2 type of solid lubricants were used as lubricants. High velocity minimum quantity solid lubricant experimental setup is fabricated to supply graphite solid lubricant into tool-chip-workpiece interface. The present investigation concentrates in comparing the cutting force and surface roughness both in solid lubricant and dry conditions.

Tribological characterization of various solid lubricants based copper-free brake friction materials – A comprehensive study

The current work is a comprehensive study dealing with the tribological performance of solid lubricants, namely graphite, tungsten disulfide, molybdenum disulfide, tin disulfide based brake friction materials with other ingredients that were developed as brake pads. The brake pads were analyzed using Industrial standards for physical, mechanical, thermal characteristics. Thermogravimetric analysis was used to study the thermal stability of the varying ingredients and developed pads. Tribological characterization was done in the pin on disc tribometer with cast iron disc as the counter face following ASTM G 99 where different loads and speeds were considered the testing parameters. Test results showed that molybdenum disulfide based brake pads had less wear rate due to excellent lubrication characteristics, while tungsten disulfide based brake pads had higher friction and thermal stability due to oxide formation. Scanning Electron Microscopy studies revealed plateau formation, pits, cracks and several other characteristics on the tested brake pads surface.

Performance assessment of CaF2 solid lubricant assisted minimum quantity lubrication in turning

Abstract Machining is one of the most widely used manufacturing processes and conventional cutting fluids have been used in large quantity to tackle the effects of heat generated during metal cutting. Looking at the effects of the cutting fluids on the environment as well as an increase in total production cost, the performance of CaF2 solid lubricant assisted minimum quantity lubrication in turning is studied. The performance of solid lubricant is judged by measuring surface roughness, chip-tool interface temperature and tool flank wear in different machining conditions. The effect of different concentration of solid lubricant is analyzed under various cutting conditions. A comparison of the results is provided with those obtained in dry, wet and minimum quantity lubrication (MQL) machining. The results indicate the improvement in process performance with the application of solid lubricant assisted lubrication. The use of the solid lubricant with MQL can be considered as a low-cost environment-friendly alternative.

IMPROVEMENT IN MACHINING PERFORMANCE OF INCONEL 718 WITH SOLID LUBRICANTS

From the last decade, the use of high corrosion resistance, high strength superalloys (mostly Ni- or Ti-based) at elevated temperature have significantly increased in aerospace or transport industry. Such materials are tremendously difficult to cut, develop a high temperature and deteriorate the quality of the components leading to tool wear. In place of using the cutting fluid, strict environmental limit develops new cutting methods or techniques for enhancing the tool life. This study demonstrates the performance of solid lubricants (hexagonal boron nitride and graphite) on surface quality. Tool geometry and cutting variables were selected for machining Inconel 718 with TiAlN-coated carbide inserts. The comparison has been conducted between solid lubricant assistant machining and dry machining. The studies demonstrate that the performance of solid lubricants is better than dry machining. There is 10% to 18% reduction in surface roughness with solid lubricants as compared to dry machining.

Tribological performance of solid lubricant contained tin-zinc alloy coating

Tribological performance of solid lubricant contained tin-zinc alloy coating

A Metal Cutting Approach to Investigate the Tribological Properties of Nano Crystalline Boric Acid and the Effect of its Carrying Medium

The pin on disc (POD) tests revealed an inverse relationship between coefficient of friction and the particle size of boric acid. So, as the properties of materials are changing with respect to its spatial dimension, the tribological performance of solid lubricant in the metal cutting is a matter of research. The present work aims at investigating the effect of variation of particle size of boric acid in the nano level in the machining of hardened steel. Canola oil and SAE 40 oil are tested as the carrying media for nano crystalline boric acid. In both cases, all the machining parameters viz. cutting forces, tool temperatures and surface roughness increased with the decrease of the particle size in nano level. The effect of carrying medium is also targeted and SAE 40 oil has been found as the best.

Experimental investigation to study the performance of solid lubricants in turning of AISI1040 steel

Machining is one of the most fundamental and indispensable processes of the manufacturing industry. The heat generated in the cutting zone during machining is critical in deciding the workpiece quality. Though cutting fluids are widely employed to carry away the heat in machining, their usage poses threat to ecology and the health of workers. Hence, there arises a need to identify eco-friendly and user-friendly alternatives to conventional cutting fluids. Modern tribology has facilitated the use of solid lubricants. The present work features a specific study of the application of solid lubricants in turning of AISI1040 steel with carbide tool. Results show considerable improvement in reducing the cutting forces, coefficient of friction between chip and tool interface, average tool flank wear, and the surface roughness of the machined surface with solid lubricants. Among the selected lubricating conditions boric acid performed well compared to graphite. Chip thickness ratio is also evaluated to study the lubricating action of selected solid lubricants during turning.

ChemInform Abstract: A Comparison of Oxidation and Oxygen Substitution in MoS2 Solid Film Lubricants

Abstract Significant advancements in the production of low friction, long wear life, sputter-deposited MoS 2 lubricant coatings have been made in the last decade. The introduction of multi-layered coatings, the establishment of careful controls on doping during DC and magnetron sputter deposition, and the implementation of ion assisted deposition have resulted in lubricants with substantially longer wear lives (up to a factor of ten greater than in the early 1980s) and lower sliding friction coefficients. A major research effort, designed to improve the performance of solid lubricants, involved a number of laboratories during this time period, resulting in these major breakthroughs. However, even with this concentrated effort, the typical investigation involved making an educated guess, based on previous experience, of the deposition conditions, target compositions, or post treatments that might be expected to provide improved performance of resulting coatings. One notable discovery during this time period was that typical MoS 2 films contain large quantities (up to 20 atom %) of oxygen substituted for sulfur in individual crystal lattices. In this paper we will compare the effects of this oxygen substitution with the effects of oxidation which involves a change in the oxidation number of the central molybdenum atoms within the crystals. A discussion of the relationship(s) between chemistry and coating structure and tribological performance will be presented with emphasis on defect chemistry and multiple phase interactions. Speculations on the role of coating chemistry in determining coating performance in applications such as in ball bearings will be presented.

English

Present trends in metal cutting, high speed/feed machining, hard and dry cutting set more demanding characteristics for cutting tool materials. Machining leads to high friction between tool and work piece, and can result in high temperatures, impairing the dimensional accuracy and the surface quality of products. Applications of conventional cutting fluids are a major source of pollution. Solid lubricant assisted machining is an environmental friendly clean technology for desirable control of cutting temperature. The present work investigates the role of nano coated (water based sol-gel ceramics) tools of different tool geometry (milling tool: radial rake angle and nose radius) in machining on surface quality, wear rate, cutting forces and specific energy. Multilayer coatings (Al2O3) were applied by using dip coating method on CNC tools with help of water based sol-gel ceramic solution. These coatings act as solid lubricants. The performance of solid lubricant assisted machining was studied in comparison with uncoated tool. These coatings are characterized by High Resolution Scanning Electron Microscope (HRSEM), Scratch test analysis and nanoindentation.

Experimental investigation to study the effect of solid lubricants on cutting forces and surface quality in end milling

Milling is a widely employed material removal process for different materials. It is characterized by high material removal rate. Machining leads to high friction between tool and workpiece, and can result in high temperatures, impairing the dimensional accuracy and the surface quality of products. Application of conventional cutting fluid may not effectively control the heat generation in milling. Besides, cutting fluids are a major source of pollution. Solid lubricant assisted machining is an environmental friendly clean technology for desirable control of cutting temperature. The present work investigates the role of solid lubricant assisted machining with graphite and molybdenum disulphide lubricants on surface quality, cutting forces and specific energy while machining AISI 1045 steel using cutting tools of different tool geometry (radial rake angle and nose radius). The performance of solid lubricant assisted machining has been studied in comparison with that of wet machining. The results indicate that there is a considerable improvement in the process performance with solid lubricant assisted machining as compared to that of machining with cutting fluids.

A comparison of oxidation and oxygen substitution in MoS 2 solid film lubricants

Significant advancements in the production of low friction, long wear life, sputter-deposited MoS 2 lubricant coatings have been made in the last decade. The introduction of multi-layered coatings, the establishment of careful controls on doping during DC and magnetron sputter deposition, and the implementation of ion assisted deposition have resulted in lubricants with substantially longer wear lives (up to a factor of ten greater than in the early 1980s) and lower sliding friction coefficients. A major research effort, designed to improve the performance of solid lubricants, involved a number of laboratories during this time period, resulting in these major breakthroughs. However, even with this concentrated effort, the typical investigation involved making an educated guess, based on previous experience, of the deposition conditions, target compositions, or post treatments that might be expected to provide improved performance of resulting coatings. One notable discovery during this time period was that typical MoS 2 films contain large quantities (up to 20 atom %) of oxygen substituted for sulfur in individual crystal lattices. In this paper we will compare the effects of this oxygen substitution with the effects of oxidation which involves a change in the oxidation number of the central molybdenum atoms within the crystals. A discussion of the relationship(s) between chemistry and coating structure and tribological performance will be presented with emphasis on defect chemistry and multiple phase interactions. Speculations on the role of coating chemistry in determining coating performance in applications such as in ball bearings will be presented.

Influence of film thickness on the performance of solid lubricants : H. J. Sauer, R. E. Schowalter and S. V. Mahate, Lubrication Eng., 27 (4) (1971) 110–114; 5 figs., 3 tables, 8 refs.

Influence of film thickness on the performance of solid lubricants : H. J. Sauer, R. E. Schowalter and S. V. Mahate, Lubrication Eng., 27 (4) (1971) 110–114; 5 figs., 3 tables, 8 refs.

Some Friction Studies of Deva Metal

IN THE QUEST for more sophisticated bearing alloys, to deal with high temperature operations, considerable attention has been paid in the past two or three years to combinations of solid lubricants and organic and inorganic binders. Thus, sodium silicate and certain synthetic resins have been suggested as means of cohering solid lubricants, to enable them to be formed or moulded. There are obvious difficulties in this approach except for bearings which need have a short life, as in rocketry. On the ground, where weight is not all‐important and where bearing life is important, one wonders whether certain conventional solutions of the problem of high temperature lubrication have received the exploitation they deserve. The performance of solid lubricants have received adequate attention in various countries, and it would seem that graphite and molybdenum disulphide continue to take first place. They exhibit a characteristic coefficient of friction of between 0.09 and 0.11, for continuous thin films formed on smooth substrates.