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Amitava Ghosh
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Amitava Ghosh
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Amitava Ghosh
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Ghosh, A.
Ghosh, Amitava
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33 results
Now showing 1 - 10 of 33
- PublicationCharacteristics of aerosol produced by an internal-mix nozzle and its influence on force, residual stress and surface finish in SQCL grinding(01-02-2017)
;Verma, N. ;ManojKumar, K.A tiny amount of cutting fluid is atomised and consumed at a very low rate in SQCL (small quantity cooling lubrication) grinding process and delivered in grinding zone. Grindability is significantly influenced by aerosol characteristics. In the present work, CFD (computational fluid dynamics) based modelling of the aerosol (air atomised water) produced by an internal-mix nozzle was carried out and validated. Various parameters, which are significantly pertinent to grindability, like droplet diameter, droplet velocity and heat transfer coefficient, were in the focus of the study. The model suggests that the SQCL technology can be effectively used at comparatively high atomising pressure with reduced flow rate for achieving adequate level of heat transfer coefficient. It was further concluded that higher flow rates or atomising pressure increases the wettable area, helping in reduction of the grinding zone temperature. Intensity of the tensile residual stress and tangential grinding force were found to be reduced in both cases but the former one was more sensitively influenced by increase in atomising pressure. - PublicationAssessment of cooling-lubrication and wettability characteristics of nano-engineered sunflower oil as cutting fluid and its impact on SQCL grinding performance(01-11-2016)
;Manojkumar, K.In small quantity cooling lubrication (SQCL) grinding, small quantity of cutting fluid is air-atomized to serve the purpose of cooling and lubrication during the process. As the flow rate of cutting fluid is intended to be set as low as possible, it is essential to develop high performance cutting fluids. In the present work, it has been attempted to enhance cooling-lubrication and wetting characteristics of a bio-degradable flower seed extracted oil, namely sunflower oil, with suspension of multi-walled carbon nano tubes (MWCNT). The suspension was realized by ultrasonic agitation provided through a 700 W probe sonicator. This new generation fluid was used as a cutting fluid in small quantity cooling-lubrication (SQCL) mode; for grinding hardened AISI52100 steel by a vitrified bonded alumina wheel. Thermal conductivity, anti-frictional properties and therefore the cooling-lubrication characteristics of sunflower oil could be enhanced significantly by the dispersion of nanoparticles. Similarly, wettability of the ordinary sunflower oil was substantially improved with nano-suspension. Augmentation of its overall quality by such nano particle suspension subsequently led to remarkable reduction in requirement of specific energy in the grinding process, as compared with the values obtained by using ordinary sunflower oil (SQCL mode) and soluble oil (delivered in conventional flood and SQCL mode). The wear rate of wheel was also significantly minimized and Ft/Fn ratio could be kept at steady and lower level, which depict the better sharpness retention of grits under nano-SQCL environment. Surface quality was superior under the nano-SQCL environment. Compressive residual stress could be achieved on the ground surface along with acceptable surface roughness. - PublicationAn experimental evaluation of solid lubricant based nanofluids in small quantity cooling and lubrication during grinding(01-01-2017)
;Paul, SourabhSmall quantity cooling lubrication (SQCL) with commercially available metal working fluids (MWF) and nano-fluids has been attempted successfully in machining and grinding. Solid lubricants also provided some benefits in grinding of metallic alloys. However, there are very few studies using molybdenum di-sulphide (MoS2) and hexagonal boron nitride (hBN) dispersed nanofluids applied in SQCL mode in grinding. The aim of the present work is to experimentally study improvement in grinding of EN31 steel using alumina grinding wheel with aqueous MoS2 and hBN nano-fluids. The grinding study is supported by detailed tribometry at 1 m/s sliding speed to reveal the possible reasons behind such improvement. MoS2 dispersed nano-fluids provided minimum coefficient of friction in ball-on-disc test. It also provided the maximum reduction in specific grinding energy and improvement in surface finish with respect to flood cooling. hBN dispersed nano-fluids could not match the performance of MoS2 dispersed nanofluids both in ball-on-disc and grinding experiments. - PublicationHigh speed turning of AISI 4140 steel using nanofluid through twin jet SQL system(18-12-2013)
;Roy, SougataApplication of small quantity lubrication (SQL) technology in high speed machining is being recognized as a sustainable approach for achieving suitable cooling/lubrication in machining zone. Present investigation focused on effectiveness of SQL with nanofluids in high speed turning of AISI 4140 steel with a TiN-top coated multilayered carbide insert and explored the advantages of using a twin-jet SQL system instead of a single jet one. SQL system was developed in-house with external-mix nozzles. The experiment was conducted varying the cutting velocity at two different feed rates (0.05mm/rev and 0.10mm/rev) with conventional coolant and nanofluids. Immediate improvement in machinability and the quality of turned surface was observed with twin-jet nanofluid SQL. A significant reduction of force and specific energy could be achieved by using 3vol% alumina and 1vol% multi walled carbon nano tube (MWCNT) nanofluid instead of soluble oil. The MWCNT nanofluid was found to be superior to alumina nanofluid in reduction of tensile residual stress. Such a reduction is typically an indirect indication of reduction of cutting zone temperature, which could be achieved due to enhanced level of lubricity at chip-tool interface and enhanced level of heat dissipation ability of the nanofluids. Improvement in retention of sharpness of tool cutting edges was also observed under nanofluid-SQL environment, which could have played important role in improvement of surface quality. Copyright © 2013 by ASME. - PublicationGrinding of Ti-6Al-4V Under Small Quantity Cooling Lubrication Environment Using Alumina and MWCNT Nanofluids(26-04-2017)
;Paul, Sourabh ;Singh, Abhinav KumarTi-6Al-4V is a difficult-to-grind material as chips tend to adhere to the grit materials of an abrasive wheel due to its chemical affinity. In the present work, it has been attempted to improve the grindability by application of small quantity cooling lubrication (SQCL) technology using nanofluids, namely, multiwalled carbon nanotube (MWCNT) and alumina nanofluid. The suitability of nanofluids was experimentally evaluated in reciprocating surface grinding using a vitrified SiC wheel. Substantial improvement in grindability under the influence of MWCNT nanofluid (SQCL) could be achieved compared to soluble oil (flood). Reduction of specific grinding forces and specific energy was observed due to the combined effect of superior heat dissipation and lubrication abilities; when the latter one was realized through on-site rolling of MWCNT strands, inter-tubular slip and solid lubrication of the film adhered onto the wheel surface. These outperforming characteristics of MWCNT nanofluid helped in retaining grit sharpness superiorly, thus resulting in better surface finish and less re-deposition of metal on the ground workpiece. On the contrary, Al2O3 nanofluid (SQCL) underperformed even soluble oil (flood). For an ageing effect, Al2O3 nanoparticles resulted in abrasive agglomerates, which led to its failure, despite its good heat dissipation capability. - PublicationExperimental and theoretical investigation on cutting forces in off-centre micro ball end milling(01-11-2018)
;Baburaj, M.; Free-form surfaces and micro features are finish machined by a micro ball end mill by removing steps left behind by flat end mill in the previous operation. For effective machining, off-centre ball end milling is employed in such a way that rubbing zone near ball tip is avoided. After confirming the limits of angular immersion from full-slot experimental results, both down and up off-centre milling experiments are conducted on edges of steps created on a test piece. The micro milling forces in off-centre mode are also investigated theoretically using a mechanistic model that considers the geometry of micro ball end mill and basic mechanics of cutting. The amplitudes of predicted forces match well with experimental values and the deviations in the experimental values arise out of micro level unevenness in the step edge. The up milling with lower transverse force is found to be more suitable for machining of thin features. - PublicationOn grinding force ratio, specific energy, G-ratio and residual stress in SQCL assisted grinding using aerosol of MWCNT nanofluid(01-01-2021)
;Manoj Kumar, K.In the present investigation, water based multi-walled carbon nanotube (MWCNT) dispersed nanofluid was produced and used as a cutting fluid in small quantity cooling lubrication (SQCL) assisted grinding of hardened AISI52100 steel. The work material was ground by an alumina wheel. The SQCL technology utilizes atomized aerosol of liquid grinding fluid. Use of MWCNT nanofluid aerosol in place of soluble oil was found to be substantially beneficial in reduction of specific energy and development of compressive residual stress on ground surface. The steady and lower value of the force ratio (tangential to normal grinding force, Ft/Fn) was suggestive of the superior lubrication and grit sharpness retention ability of the aerosol of MWCNT nanofluid. Higher compressive residual stress on the ground surface under MWCNT nanofluid environment suggests lesser grinding zone temperature, which can be attributed to its superior wettability, lubricity and heat dissipation ability of the MWCNT nanofluid. The consumption rate of grinding fluid in SQCL was varied. It could be reduced to 200 ml/h for MWCNT nanofluid to obtain an almost similar or better effect to that of 500 ml/h for soluble oil. Lesser surface tension of MWCNT nanofluid, compared to its counterpart, seemed to facilitate wetting, thus improving lubrication and heat transfer capability further. - PublicationAnti-frictional role of diamond and graphite suspended bio-oil based nano-aerosols at sliding interface of Al-SiCp and WC-6Co(01-01-2021)
;Guntreddi, BalakrushnaCurrent study investigates tribo-phenomena at sliding interface of Al2124-17SiCp disc and WC-6Co pin and explores suitability of nano-oil aerosols as lubricants. They form chip-tool tribo-pair in machining. Ploughing, adhesion, abrasion were predominant under dry sliding. Adhesion and friction-coefficient (COF) were severer with higher normal load and lower sliding velocity. Aerosol of palm-oil arrested adhesion of aluminium on carbide pin and reduced COF by 80–82% through film-lubrication but at low load conditions. Diamond/graphite nanoparticles (1 wt%) suspension helped palm-oil sustain film-lubrication at sliding interface even in extreme conditions, reducing COF further and arresting adhesion phenomenon. Rolling of near-spherical nano-diamonds or basal-plane shearing within graphite nano-platelets caused additional reduction in friction. Graphite nano-aerosol was superior and similarly effective in high-speed milling as SQL-medium. - PublicationHigh-speed machining of aluminium alloy using vegetable oil based small quantity lubrication(01-01-2020)
;Guntreddi, BalakrushnaIn an attempt to investigate the effectiveness of vegetable oil based small quantity lubrication in high-speed machining of aluminium, this study finds that its usefulness is more significant in an intermittent cutting process like end milling than in turning, where continuous cutting happens. The investigation was carried out using small quantity lubrication aerosol, produced by air atomization of sunflower oil at the rate of 100 ml/h for each cutting zone. In the high-speed turning operations, uncoated and polycrystalline diamond–tipped WC inserts were used. 5%–20% reduction of cutting force could be realized by small quantity lubrication application, compared to dry environment. The highest order of reduction was observed when the cutting velocity was increased from 700 to 1000 m/min. At lower velocities, small quantity lubrication effect was almost insignificant. However, high-speed end milling operations received substantially superior benefit by small quantity lubrication application. The reduction of feed force was 30% or more among different cutting speeds. The beneficial effect of small quantity lubrication application was significantly more in machining commercially pure 1050 grade of aluminium than 7075 alloy. The required prevalence of the thick-film lubrication at the interface of chip and tool rake for arresting any possible diffusion of aluminium to tool material was significant in the intermittent cutting since every cutting edge drew in fresh micro-droplets of lubricant before resuming cutting in its next cycle of engagement with workpiece. Interestingly, the end milling performance of small quantity lubrication–assisted uncoated carbide was so good that diamond-coated tools were not necessary. Surface roughness profiles, chip morphology and traces of built up edge formation were critically investigated and the results clearly indicated the predominantly more favourable outcome of small quantity lubrication application in end milling, compared to turning. - PublicationSynthesis of MWCNT nanofluid and evaluation of its potential besides soluble oil as micro cooling-lubrication medium in SQL grinding(01-04-2015)
;ManojKumar, K.Grinding, being a high specific energy involving process, essentially requires a high-performance cutting fluid when small quantity lubrication (SQL) is employed. In SQL, a small volume of metal working fluid is broken into micro-droplets by a compressed air jet so that the aerosol jet cools and lubricates machining zone more efficiently than flood cooling. In the present work, a new generation grinding fluid was indigenously synthesized by dispersing multi-walled carbon nanotube (MWCNT) in deionized water for SQL grinding of steel by an alumina wheel, and its capability was evaluated in depth in comparison with the commercially used soluble oil. It was observed that a maximum of 1 vol% MWCNT could be dispersed without any settling tendency over 48 h, which subsequently rendered the highest thermal conductivity to the nanofluid sample. It was approximately 35 % higher than that of soluble oil. In a simulative ball (Al2O3) on disc (hardened AISI 52100 steel) test, it was further found that this nanofluid sample was 30 % more lubricious than its counterpart. The higher heat dissipation ability and better lubricity finally resulted in remarkably superior performance of MWCNT nanofluid to that of soluble oil. In comparison with the later MWCNT nanofluid, in particular, at 3 bar of atomizing air pressure and 350 ml/h flow rate, could offer substantially better G ratio, significantly reduce tangential grinding force and produce comparable surface finish. Additionally, presence of more number of long and sheared chips and less spherical chips in the collected sample was a clear indicator of reduction in grinding temperature when soluble oil was replaced by MWCNT in SQL mode.