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The quality of the surface being machined and tool life are greatly affected by heat generated during machining. Abundant use of cutting fluid leads to higher production rates and a threat for environment and worker’s health. Hence, the need is to identify eco-friendly lubricants. The purpose of the current work is to investigate the effects of solid lubricants (boric acid and molybdenum disulphide) mixed with oil during turning of EN-31 using cemented carbide tools. The concentration of solid lubricants in oil is varied to analyze output parameters such as surface roughness, process temperature, power consumption and tool wear.

EN 31 steel material is machined at various cutting speeds and constant feed and depth of cut to determine the effects of dry, wet and solid lubricant assisted machining.

Experimental study revealed that the solid lubricants performed better while machining and therefore it may be considered as environment friendly and cost effective way of lubrication as compared to flood cooling.

The work can be extended to identify the effects of solid lubricants on micro hardness and cutting force.

From the findings of the work, solid lubricants may be considered as suitable choice as compared to fluid cooling because it improves process performance without much affecting the environment and worker’s health.

So far the use of solid lubricants in machining is limited. The results of the work will be useful to explore various efficient way to apply solid lubricants.

The purpose of the paper is to assess the influence of the volume fraction solid lubricants like talc lead and graphite in oil separately and in combination towards controlling the sliding wear behaviour of a grey cast iron and understand the factors controlling the response of the material in a given set of experimental conditions.

The composition of the lubricating medium (oil) has been changed by dispersing 5 per cent graphite, talc and lead particles separately and in combination. Sliding wear tests were conducted on grey cast iron samples over a range of applied pressures. Parameters determined were wear rate and frictional heating. The wear behaviour of the samples was further substantiated through the features of wear surfaces, subsurface regions and debris particles. Material removal mechanisms and factors responsible for a specific response of the samples have also been analysed.

The wear rate increased with increasing applied pressure. Addition of graphite and lead to the oil separately or in combination brought about a reduction in the wear rate of the samples; talc and talc + lead produced a reverse trend. Temperature near the specimen surface increased with test duration and applied pressure. The test environment influenced the frictional heating in a manner similar to that of the wear rate. Adhesion and abrasion were observed to be the operating material removal mechanisms. Smearing of the solid lubricating phase and delamination resulting from cracking tendency also controlled the wear response.

Oil is a very popular lubricant used in engineering applications involving friction and wear. Solid lubricants are used along with the oil. The nature, characteristics and content of the solid lubricants very much control the performance. Limited information is available pertaining to assessing the influence of the type and fraction of solid lubricants in the oil towards controlling the wear behaviour of cast irons (popularly known tribomaterials). The present study enables to understand the effectiveness of talc, lead and graphite in oil towards governing the wear characteristics of cast iron and analyse wear mechanisms and controlling parameters.

Graphite and talc are available in nature in abundance. Graphite is a popularly known solid lubricant, while talc is less explored. Lead is also well-known as a solid lubricant but poses health hazard in practice due to its toxic nature. The present study explores the lubricating capability of talc when mixed with oil separately or in combination with lead and graphite towards controlling the wear response of a grey cast iron. It enables to understand the factors responsible for the specific response of talc.

Assessment of the lubricating potential of talc as a possible substitute to lead is important in view of the toxic nature of the latter. If successful, the exercise could enable to replace lead with talc.

The present manuscript is an original piece of the author's research work.

This study aims to form composite solid lubricant coatings on the surface of bearing steel, which can significantly improve the tribological properties of thrust cylindrical roller bearings (TCRBs). Phosphating films possess microscopic porosity that typically needs to be sealed with oil, grease or wax. Due to its unique crystal structure, the phosphating film itself also exhibits a certain degree of lubricity. In this study, solid lubricants are used to fill the pores of the phosphating film. By combining the phosphating film with solid lubricants, lubrication and wear reduction can be achieved.

In this study, the surfaces of the shaft washer (WS) and seat washer (GS) were treated with zinc-phosphating. Subsequently, a solid lubricant solution (polytetrafluoroethylene [PTFE], MoS₂ and graphite) was sprayed onto the phosphated samples at concentrations of 1 , 2  and 3 g/L. The porous and adsorptive nature of the phosphating film was used to embed the solid lubricant particles into the film, thus forming a composite lubrication layer containing solid lubricants on the surface of the bearing steel.

The addition of solid lubricant materials has shown significant potential in reducing wear losses compared with phosphated samples without such additives. Increasing the amount of solid lubricant added can facilitate the formation of a transfer film, which further enhances the protective properties. However, it is important to note that excessive amounts of solid lubricant material can contribute to seizure, leading to increased wear losses of the cage and a higher average coefficient of friction (ACOF).By spraying a PTFE solution with a concentration of 2 g/L, the lowest ACOF and cage wear loss were achieved, resulting in reductions of 60.5% for the ACOF and 89.4% for the cage wear loss. Similarly, when spraying a graphite solution with a concentration of 3 g/L, the lowest wear losses for GS and WS were observed, with reductions of 51.7% for GS wear loss and 38.9% for WS wear loss.

The combination of the phosphating film and solid lubricants aims to achieve lubrication and wear reduction, providing a new approach to wear-resistant technology for TCRBs.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2023-0231/

This paper aims to find out the tribological performance and self-lubricating mechanism of the laser-textured surface filled with solid lubricant in rolling friction pair.

The textures on the surfaces of GCr15 bearing steel were produced by acousto-optic Q diode-pumped yttrium aluminum garnet laser with the technology of “single pulse one time, repeating at intervals” and filled with composite solid lubricant. The tribology tests were conducted on the MMW-1A universal friction and wear testing machine.

It was found that the solid-lubricated micro-textured surface can reduce the friction coefficient effectively. The MoS2/PI composite solid lubricant works better than the single MoS2 solid lubricant, and the ratio of PI/MoS2 + PI at 20 per cent is the best recipe. The friction coefficient of the sample surfaces decreases first and then increases with the increase in texture densities, and a texture density of 19.6 per cent has the best effect on friction reduction. The friction coefficient of the textured surfaces gradually decreases with the increase in both rational speed and load. For the same texture density, the friction coefficient of textured surfaces decreases slightly with the increase in diameter. Furthermore, the mechanism of “rolling-extrusion-accumulation” occurred on the textured surface can collect the solid lubricant, thereby, improve the effect of lubricating and anti-friction.

The results of the experimental studies demonstrated the application prospect of laser surfaces texturing combined with solid lubricant in rolling friction pair.

LUBRICANTS capable of lubricating mechanisms intended for use in present and future missile satellite systems and spacecraft must provide long‐time operational reliability under a variety of earth and space environmental and operational conditions. For example, the lubricants will be exposed to conditions attendant to ground activities; to short‐time operations during the launch, ascent and re‐entry and to extended operations in orbit. Ground operations include exposure to test and check out procedures, handling and transportation, exposure to elements and to possible fuel or oxidizer spillage. Under launch, ascent, and re‐entry, the effects of heavy shock, severe vibration, high and low temperature, and possibly fuel and oxidizer exposure, may be expected. When in orbit, the lubricant must still provide satisfactory lubrication despite the effects of ultra‐high vacuum, zero gravity, temperature extremes, and radiation exposure. Add to these requirements the compatibility factor and some idea of the demands placed on aerospace lubricants may tend to take form. It is unlikely that any one lubricant, even of the solid film type will be applicable to all these conditions; therefore, it appears quite likely that the solid film will be individually tailored to each specific application. As will be noted further that the Denver Division of the Martin Company allows the use of three distinct type solid film dry lubricants. It is expected that more will be added when environmental testing proves reliable under a specific set of requirements.

The purpose of this paper, an R&D project, is to select Globally Harmonized System of Classification and Labeling of Chemicals (GHS)-unclassified white solid lubricants for formulating special lubricating oils, greases and pastes to prevent tribological systems against fretting wear.

The scientific methodology reads as follows: market research to select appropriate additives according to the purpose of the R&D project; screening tests to determine the technical performance of the additives; advanced technical studies and tests to validate the technical performance of the lubricating additives; determination of the reaction layers; and clarification of the build-up mechanism of the reaction layers (practical tests).

The findings of the R&D project can be summarized as follows: the selected white solid lubricants perform in lubricating oils, greases and pastes highly effective against fretting wear. The performance could be shown on the basis of representative test results and highlights its advantages compared to the state of the art.

The research team faced some challenges during the R&D project – the unsuitability of standard test measurements as well as DIN, ISO and ASTM test parameters led to limitations and increased effort.

The motivation and main target to conduct the R&D project was to increase the consumer and operator safety by using unclassified (GHS) high performance lubricants. The findings of the project show clearly that the tasks could be fulfilled. Special, unclassified (GHS) selected white solid lubricants are able to form a reaction layer on metal surfaces and separate effectively the surfaces within the tribological system. No fretting wear accrued. The consumer can gain substantial benefits on the economical side as well as on the ecological side.

This paper aims to investigate the effect of CaF₂ (calcium fluoride) addition as a solid lubricant on the friction and wear behaviour of sintered Fe-Cu-C materials under different loads.

In this study, the effects of CaF₂ added in varying weight percentages on the friction-wear properties of Fe-2Cu-0.8C alloys are investigated. Five Fe-2Cu-0.8C-based compositions comprising CaF₂ in 0, 3, 6, 9 and 12 Wt.% were prepared using the single-stage compaction and sintering technique. Friction coefficient, wear loss, hardness and compressive strength of the specimens were measured. The worn-out surfaces were analysed using a scanning electron microscope. Friction and wear tests were carried out on pin-on-disc machine under dry sliding conditions at room temperature.

The alloy with 3 Wt.% CaF₂ was found to be useful in improving wear and friction properties, whereas higher contents of CaF₂ resulted in increased wear and friction. Apart from enhanced tribological properties, a slight decrease in the compressive strength was also observed in the 3-Wt.%-CaF₂-added sample. Adhesion and abrasion were the prominent wear types observed during this study.

A new self-lubricating composite is developed where CaF₂ is used as a solid lubricant in a Fe-Cu-C-based matrix. CaF₂, being a high-temperature lubricant, is tried and tested for friction and wear at room temperature, and the results show that the addition of CaF₂ in Fe-Cu-C improved its friction and wear properties. Thus, the developed material can be used for antifriction applications.

The Presidential Address to the Liverpool Engineering Society by Mr. Farthing (the salient points of which are reproduced in this issue) has particular bearing upon lubrication and especially on young lubrication engineers. Mr. Farthing stressed the very wide field open to young engineers and the difficulties associated with training in order to cover as wide a field as may be necessary. It is usually so important to gain a wide knowledge before one can specialise and this is certainly the case with lubrication engineers. One cannot begin to fully appreciate the intricacies of a lubrication system with all its accessory components lubricating and guarding, for example, a large motive power plant or rolling mill, until one has more than a mere working knowledge of the plant itself, the duties it must perform, how it performs them and the snags that arise which might be overcome by correct lubrication. In view of the fact that lubrication systems are just as important in a textile mill as in a power station or a large brick works, the almost impossible‐to‐achieve‐range of knowledge that would simplify the work of a lubrication engineer is very obvious. Fortunately, lubricating principles apply to most cases and knowing how to apply one's knowledge from basic principles is the key to success in this difficult profession.

Inconel 718 is difficult to machine due to its high toughness and study hardenability. Though the use of cutting fluids alleviates the problem, it is not sustainable. So, supply of a small quantity of specialized coolant to the machining zone or use of a solid lubricant is a possible solution. The purpose of the present work is to improve machinability of Inconel718 using graphene nanoplatelets.

In the present study, graphene is used in the machining of Inconel 718 alloy. Graphene is applied in the following two forms: as a solid lubricant and as an inclusion in cutting fluid. Graphene-based self-lubricating tool and graphene added nanofluids are prepared and applied to turning of Inconel 718 at varying cutting velocities. Performances are compared by measuring cutting forces, cutting temperature, tool wear and surface roughness.

Graphene, in both forms, showed superior performance compared to dry machining. In total, 0.3 Wt.% graphene added nanofluids showed the lowest cutting tool temperature and flank wear with 44.95% and 83.37% decrease, respectively, compared to dry machining and lowest surface roughness, 0.424 times compared to dry machining at 87 m/min.

Graphene could improve the machinability of Inconel 718 when used in tools as a solid lubricant and also when used as a dispersant in cutting fluid. Graphene used as a dispersant in cutting fluid is found to be more effective.

SOLID lubricants such as molybdenum disulphide and graphite have been incorporated in bonded lubricating films for some years, but work is constantly proceeding to develop improved products that provide reduced friction, less wear, are easier to use, or have other valuable features. One of the more recent additions to this type of lubricant is graphite fluoride.