HARD TURNING MACHINABILITY PROCESS BY GRAPHENE OXIDE ASED NANO-LUBRICANT THROUGH MULTI-NOZZLE INJECTION MQL SYSTEM

Abstract

ABSTRACT “HARD TURNING MACHINABILITY PROCESS BY GRAPHENE OXIDE ASED NANO-LUBRICANT THROUGH MULTI-NOZZLE INJECTION MQL SYSTEM” The present invention provides a graphene oxide-based nanofluid for hard turning of hardened AISI D2 steel, improving CNC machining performance through a multi-nozzle MQL (minimum quantity lubrication) system. Graphene oxide nanoparticles, dispersed in LRT 30 base oil at concentrations from 0.05% to 0.5% wt., provide superior cooling and lubrication. The nanofluid reduces tool wear, cutting temperature, power consumption, and noise emission while enhancing surface quality and accuracy. The process incorporates a two-step nanofluid preparation involving preheating, stirring, and ultrasonic treatment. Optimal performance is achieved at 0.5% wt., ensuring high machining quality and dimensional accuracy. The method offers a sustainable, eco-friendly solution, reducing manufacturing costs and environmental impact by utilizing cost-effective CVD-coated carbide tools with wiper geometry, a novel approach in hard turning operations. Figure 1

Specification

Description:TECHNICAL FIELD
[0001] The present invention relates to the field of mechanical engineering, and more particularly, the present invention relates to the hard turning machinability process by Graphene Oxide ased nano-lubricant through multi-nozzle injection MQL system.
BACKGROUND ART
[0002] The following discussion of the background of the invention is intended to facilitate an understanding of the present invention. However, it should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was published, known, or part of the common general knowledge in any jurisdiction as of the application's priority date. The details provided herein the background if belongs to any publication is taken only as a reference for describing the problems, in general terminologies or principles or both of science and technology in the associated prior art.
[0003] The use of conventional fluid is inadequate in effectively dissipating heat during the process of high-speed cutting. Therefore, nanofluids can be used as a replacement cutting fluid in the Minimal Quantity Lubrication (MQL) process. The exceptional thermal conductivity of nanofluids enhances the cooling and lubrication processes in the MQL process. Furthermore, within a conventional flood cooling setting, a substantial quantity of synthetic oil is employed, posing challenges in terms of disposal and posing potential health risks to the operator. Currently, the MQL system is widely preferred in many sectors due to its sustainability benefits and its capacity to provide improved cooling and lubrication during machining applications.
[0004] In the process of machining hardened steel, the presence of high friction at the interface between the tool and workpiece leads to an elevation in the cutting temperature. This, in turn, has a notable impact on the overall quality of the finished product. Lubrication of the machining zone is achieved by the application of metal cutting fluids. The machining zone generates intense heat, necessitating the use of cutting tools of superior quality and imposing limitations on the machining settings. The improved edge stability and high hardness value of CBN, PCBN, and Ceramic tools make them useful in hard turning operations. Nevertheless, the high price of these tools significantly impacts the entire production expenses of the company or manufacturer. In order to address this particular circumstance, the present invention introduces commercially accessible, cost-effective coated carbide inserts specifically designed for the purpose of hard turning. This study employs coated carbide inserts with wiper finishing geometry, which demonstrates superior performance compared to alternative geometry cutting tools in terms of surface finish. The coatings on the tool substrate are applied using the chemical vaporization deposition process. The application of coating layers serves to create a barrier between the workpiece and tool substrate during the machining process. This barrier prevents the tool material from being subjected to excessive heat generated at the cutting zone. Consequently, the lifespan of the tools is extended, leading to improved surface quality. In addition, CBN, PCBN, and Ceramic tools are mostly utilized in arid conditions, resulting in initial damage to the cutting tool due to the sudden increase in temperature inside the cutting area and the significant friction between the workpiece and cutting tool. In order to achieve cost-effectiveness and high precision in the production process of hardened materials during the turning operation, it is imperative to carefully choose an appropriate cooling and lubrication strategy. Therefore, it can be argued that high-cost CBN, PCBN, and ceramic tools, which incorporate advanced cooling and lubrication techniques known as nanofluid-assisted minimum quantity lubrication technique (Nano-Fluid MQL), may be overshadowed by the availability of low-cost CVD-coated cutting tools with wiper finishing geometry.
[0005] The MQL machining technique enables the utilization of nanofluids in hard turning, therefore enhancing machining characteristics and ensuring an ecologically sustainable cutting zone with increased accessibility. This, in turn, reduces frictional contact between the tool and work surfaces. The present study introduces a novel approach that combines Graphene oxide (GO) based nanofluid with a multi-nozzle injected Minimum Quantity Lubrication (MQL) system to address the aforementioned issues encountered in the turning process of hardened Steel. By incorporating Graphene oxide (GO) nanoparticles into LRT 30 mineral oil, the cutting fluid's heat transfer and lubrication characteristics may be enhanced, resulting in improved cutting performance and less tool wear during severe turning. Utilising Graphene oxide nanofluids as cutting fluids can result in enhanced surface accuracy, decreased cutting force, and prolonged tool lifespan. In a multi-nozzle assisted MQL system, coolants or lubricants are delivered via multi nozzles to the cutting tool in order to decrease friction and lower the temperature of the cutting zone.
[0006] The present study involves the application of two distinct nozzles to the flank face and rake face of the cutting tool during the hard turning process of AISI D2 steel. The base oil utilised in this research study was LRT 30, which is an iron aluminum-based spring oil. In order to enhance the thermal conductivity and lubricating characteristics of LRT 30, Graphene oxide nanoparticles were added into it and supplied using a multi-nozzle aided MQL system. After the detail analysis on the result, it can be concluded that graphene oxide based nanofluid has a great impact on machinability improvement of AISI D2 steel. The application of Graphene oxide (GO) nanofluid through the MQL system, with the assistance of multiple nozzles (double nozzles), reduces both cutting power consumption and cutting noise. This is due to the superior lubricious properties of the graphene oxide based nanofluid. This reduces production costs for the industry or manufacturer and minimizes unnecessary noise pollution, making it a step towards a sustainable manufacturing process. The application of Graphene oxide nanofluid through the MQL system, with the assistance of many nozzles, has the potential to become a promising solution for enhancing tool longevity and enhancing the surface quality of machined products, while also promoting environmental sustainability.
[0007] The presence of high friction at the interface between the tool and workpiece during the machining process of hardened steel leads to an elevation in the cutting temperature. This, in turn, exerts a notable impact on the overall quality of the finished product. Fluids for metal cutting are employed for the purpose of lubricating the machining zone. Owing to the intense heat generated by the machining area, only cutting tools of superior quality are permissible, and the machining parameters are limited. The use of CBN, PCBN, and Ceramic tools is prevalent in hard turning operations owing to their exceptional edge stability and elevated hardness metric. Nevertheless, the high cost of these equipment has a significant impact on the cost of manufacturing for the industry or company. In order to address this issue, our present invention introduces commercially accessible, affordable coated carbide inserts specifically designed for hard turning applications. This study employs coated carbide inserts with wiper finishing geometry, which outperforms other geometry cutting tools in terms of surface finish. The coatings on the tool substrate are applied using the chemical vaporisation deposition process. The application of these coating layers creates a barrier between the workpiece and tool substrate during the machining process. This barrier prevents the tool material from being damaged by the excessive heat generated at the cutting zone. As a result, the lifespan of the tools is extended and improved surface quality can be attained. Furthermore, it is worth noting that CBN, PCBN, and Ceramic tools are predominantly employed in arid settings, resulting in initial damage to the cutting tool. This damage is primarily attributed to the sudden increase in temperature inside the cutting zone and the subsequent generation of high friction between the workpiece and the cutting tool. For a cost-effective and high-precision production process of hardened materials in the turning operation, it is necessary to choose an appropriate cooling and lubrication strategy. Therefore, the utilization of low-cost cutting tools coated with CVD and featuring a wiper finishing geometry may present a more favorable option compared to the high-cost CBN, PCBN, and ceramic tools. This alternative approach incorporates an advanced cooling and lubrication technique known as nanofluid-assisted minimum quantity lubrication technique (Nano-Fluid MQL).
[0008] CBN, PCBN, and Ceramic tools are commonly investigated for the machining of hard materials, but their acquisition is expensive, resulting in an overall rise in manufacturing costs. The use of commercially available low-cost multi-CVD coated carbide tools with wiper finishing geometry is employed in this innovation. CVD coated tools have previously been utilized for harsh machining operations. However, this present study introduces the usage of wiper finishing geometry with CVD coated carbide tools, which has not been previously employed.
[0009] In order to minimize the utilization of metal cutting fluid, it is common practice to conduct hard turning operations in a dry atmosphere. Numerous industries employ synthetic metal cutting fluids as flood cooling settings throughout the machining process. Nevertheless, these metal cutting fluids offer a significant risk to the health of operators, are not environmentally friendly, and are extremely challenging to dispose of. This study primarily focuses on the use of single nozzle MQL systems in the context of hard machining. During hard machining, it is more beneficial to have several MQL mist flow in the cutting zone (Tool-workpiece contact zone) and on the major flank face of the cutting insert, as opposed to a single mist flow. There is currently no information on the impact of MQL double nozzles on the machining performance of hardened steel (AISI D2 steel) in the relevant innovation. Therefore, a thorough examination is required to ensure sustainability.
[0010] The following existing solutions are patented for machining applications:
1. Lubricating and cooling method for cutting process and device thereof
Publication number: CN102029551A
Publication type: Grant
Publication date: 24th July 2011
2. A lubrication and cooling device and a method for lubricating and cooling a work piece
Publication number: EP3313610B1
Publication type: Grant
Publication date: 29th July 2020
3. Method and device for measuring particle size of nano particle jet minimum quantity lubrication grinding droplets
Publication number: CN103454190B
Publication type: Grant
Publication date: 20th May 2015
4. System and method for dispensing a minimum quantity of cutting fluid
Publication number: US9931724B2
Publication type: Grant
Publication date: 3rd April 2018
[0011] In light of the foregoing, there is a need for Hard turning machinability process by Graphene Oxide ased nano-lubricant through multi-nozzle injection MQL system that overcomes problems prevalent in the prior art associated with the traditionally available method or system, of the above-mentioned inventions that can be used with the presented disclosed technique with or without modification.
[0012] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies, and the definition of that term in the reference does not apply.
OBJECTS OF THE INVENTION
[0013] The principal object of the present invention is to overcome the disadvantages of the prior art by providing Hard turning machinability process by Graphene Oxide ased nano-lubricant through multi-nozzle injection MQL system.
[0014] Another object of the present invention is to provide hard turning machinability process by Graphene Oxide ased nano-lubricant through multi-nozzle injection MQL system that encompasses the utilization of LRT 30 mineral oil and the commercially accessible graphene oxide (GO) nanoparticles. Nanofluid samples may be easily and cheaply produced.
[0015] Another object of the present invention is to provide hard turning machinability process by Graphene Oxide ased nano-lubricant through multi-nozzle injection MQL system that is uncomplicated, cost-effective, and small, necessitating minimal area for installation.
[0016] Another object of the present invention is to provide hard turning machinability process by Graphene Oxide ased nano-lubricant through multi-nozzle injection MQL system that has a significant economic influence and has promise for commercial utilization in machining applications.
[0017] Another object of the present invention is to provide hard turning machinability process by Graphene Oxide ased nano-lubricant through multi-nozzle injection MQL system, wherein the technology's environmentally friendly nature presents a substantial opportunity for commercialization in other machining industries.
[0018] The foregoing and other objects of the present invention will become readily apparent upon further review of the following detailed description of the embodiments as illustrated in the accompanying drawings.
SUMMARY OF THE INVENTION
[0019] The present invention relates to Hard turning machinability process by Graphene Oxide ased nano-lubricant through multi-nozzle injection MQL system.
[0020] The present study aims to suggest a sustainable nano lubricant for enhancing the process of CNC turning of hardened AISI D2 steel. Graphene oxide nanoparticles are employed in the synthesis of nano lubricants, whereas in the production of nanofluids, Graphene oxide nanoparticles are uniformly dispersed into spring oil (LRT 30). The concentration of nanoparticles in the base fluid leads to an increase in its thermal carrying coefficient, resulting in enhanced cooling at the cutting zone and a progressive improvement in overall machining performance. Moreover, the existence of an excessive amount of nanoparticles within the base fluid occasionally leads to heightened friction between the cutting tool and the workpiece, resulting in surface degradation. Consequently, the cutting temperature escalates because of this friction, thereby causing deterioration of the tool substrate as well. In order to address this issue, a comprehensive investigation was conducted on the impact of six different concentrations of graphene oxide nanofluid on the hard turning operation of AISI D2 steel. This invention involves the preparation of six wt.% concentrations of Graphene oxide (GO) nanofluids. The performance of these nanofluids during hard turning operation is studied, and the optimal concentration for using Graphene oxide (GO) nanofluids in hard turning operations is recommended to machinists and the industry. This recommendation aims to enhance the efficiency of machining processes and promote green and sustainable machining applications.
[0021] The study focused on analysing the machining properties of AISI D2 hardened steel in a newly created NFMQL (Nanofluid MQL) environment. This was achieved by utilising Multi-layer CVD coated carbide inserts with wiper finishing shape. The output responses under investigation encompass tool wear, surface roughness, cutting temperature, cutting power, and cutting noise assessment. The studies were carried out using a CNC lathe on AISI D2 hardened steel (55 ± 1 HRC). The primary applications encompass Blanking Dies, Forming Dies, Coining Dies, Slitting Cutters, Heading Tools, Long Punches, Forming Rolls, Edging Rolls, Master Tools, Beading Rolls, Intricate Punches, Extrusion Dies, Drawing Dies, Lamination Dies, Thread Rolling Dies, Shear Blades, Burnishing Tools, Gauges, Knurls, and Wear Parts. The turning process involved the use of cutting tools supplied by WIDIA Ltd, namely the ISO-designated CNMG 120408FW coated carbide (MT-CVD/ CVD-TiN-TiCN-Al2O3) with grade WK05CT. The tools are coated with three layers of TiN-TiCN-Al2O3, which were produced using the chemical vapour deposition (CVD) process. These tools possess a wiper finishing shape, which is designed to enhance the surface quality. The cutting speed (v) of 140 m/min, feed rate (f) of 0.1mm/rev, and depth of cut (d) of 0.2 mm were chosen based on published research and the recommendations of the tool manufacturer. All studies done during the hard turning operation of AISI D2 steel under graphene oxide (GO) nanofluid MQL environment maintained fixed cutting parameters for all six nanofluid concentrations. Experiments are conducted three times for each concentration of nanofluid to prevent any unforeseen mistake percentages. The average end result value is then calculated for all the trials. The machining area was supplied with a graphene oxide-based nanofluid using a Multi-Nozzle (MQL) system operating at a 6-bar air pressure, 30 mm stand-off distance and a coolant flow rate of 50 ml/hr. This was achieved through the use of double nozzles.
[0022] The size and elemental analysis of graphene oxide nanoparticles were analysed using FESEM and EDS techniques. Based on the research conducted using a Finite element scanning electron microscope (FESEM), the average size of the nanoparticles was determined to be 18 nm. Additionally, the existence of Carbon(C) and oxygen (O) elements in the sample was identified using energy-dispersive spectrometry (EDS) analysis, with percentages of 96.5 percent and 3.5 percent, respectively. Prior to nanofluid production, the graphene oxide (GO) nanoparticles undergo a preheating process for a duration of 3 hours at a temperature of 200℃ in order to eliminate moisture from the nanoparticles. Subsequently, graphene oxide (GO) nanoparticles are uniformly distributed into LRT 30, spring oil composed of iron and aluminium. This current innovation involves the preparation and development of six different concentrations of graphene oxide (GO) based nanofluids, namely 0.05%wt, 0.1%wt, 0.2%wt, 0.3%wt, 0.4%wt, and 0.5%wt. In order to achieve pre-dispersing, graphene oxide (GO) nanoparticles were introduced into the base oil LRT 30. To facilitate the immediate mixing of graphene oxide (GO) and LRT 30 oil, a mechanical stirrer was employed for a duration of 30 minutes at a speed of 1400 rpm for all concentrations. Nanofluids are created using a two-step method. Initially, nanoparticles are dispersed in the base oil. Subsequently, nanofluids with concentrations of 0.05%wt., 0.1%wt., 0.2%wt., 0.3%wt., 0.4%wt., and 0.5%wt. are mixed in a magnetic stirrer for durations of 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, and 9 hours, respectively. To prevent nanoparticle clustering in base oil, nanofluids with concentrations of 0.05%wt, 0.1%wt, 0.2%wt, 0.3%wt, 0.4%wt, and 0.5%wt were subjected to ultrasonication for durations of 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, and 8 hours, respectively. The approach for preparing nanofluids is illustrated in Figure 1. The hard turning operation was performed on hardened AISI D2 steel using multilayer CVD coated carbide tools with wiper finish geometry. The specified fixed input parameters included a cutting speed (v) of 140 m/min, feed rate (f) of 0.1mm/rev, and depth of cut (d) of 0.2 mm. To ensure accuracy, each experiment was repeated three times. The average results were then calculated for various parameters including tool wear, surface roughness, cutting temperature, cutting power, and cutting noise.
[0023] Multi nozzle application (Double nozzle) was employed to spray the developed nanofluids with high pressure into the cutting zone from two directions. 1st nozzle was kept vertically facing towards the tool- workpiece contact zone and the second nozzle was faced toward the principal flank face of the cutting tool with an angle of 45° from the cutting tool holder axis as shown in Figure. 2. For each nozzle continuous coolant flow (Graphene oxide Nano-Fluid) of 50 ml/hr was maintained with 6 bar pressure and 30 mm standoff or nozzle distance through an MQL system. The components and the configuration of the MQL system are demonstrated in Figure.2.
[0024] In order to enhance the machinability of AISI D2 steel during the turning process, an initial experiment was conducted to ascertain the ideal concentration of nanofluid. The investigation on tool wear exhibited a direct correlation between the concentration of nanoparticles in the base fluid and the gradual reduction in flank wear. As the concentration of graphene oxide (GO) nanofluid increases from 0.05% wt. to 0.5% wt., there is a gradual reduction in average tool wear was noticed. The minimum tool wear is seen when the concentration of graphene oxide (GO) nanofluid is 0.5% by weight. At the highest concentration of nanofluid, a reduction in tool wear of 32.14% was observed. At 0.5% of GO nanofluid condition lowest tool wear observed which is very low according to hard turning concern. The enhanced capacity to cool and lubricate in the cutting zone region may be due to the remarkable thermal conductivity of the nanofluid based on graphene oxide, which is paired with Mult-nozzle injection in the MQL setup. An investigation was carried out to assess the state of the tool following machining in environments with GO concentrations of 0.05% and 0.5%. Moreover, during the examination of the cutting temperature values, a significant reduction in the temperature of the cutting zone was seen at the highest concentration (0.5%) of graphene oxide (GO) nanofluid. According to the results, it has been demonstrated that a higher concentration of nanoparticles in the base fluid causes a gradual increase in thermal conductivity. The observed rise in temperature contributes to a significant reduction in the cutting zone during hard turning operations. The empirical evidence suggests a persistent reduction in temperature of 37.67% when the nanoparticle concentration in the base oil LRT 30 escalates from 0.05% to 0.5%. The examination of the findings showed a significant improvement in the quality of the surface due to an enhanced cooling and lubrication strategy. The highest recorded surface polish value obtained when the weight percentage was 0.05%, far lower than the needed level for hard turning. The surface quality get improved when the concentration of GO nanofluid was 0.5% wt., leading to a reduction in surface roughness by 30.21% compared to the surface roughness observed with a nanofluid concentration of 0.05% wt. The power consumption was found to be the lowest while using a concentration of 0.5% wt. of GO Nanofluid, in comparison to all other concentrations. The application of a 0.5% concentration of GO nanofluid resulted in a reduction of approximately 32.08% in cutting power, compared to the lowest concentration of GO nanofluid (0.05%). The increased lubrication at the highest concentration resulted in a significant decrease in friction between the tool tip and workpiece, leading to a reduction in cutting force and thus decreasing power consumption and reduction in noise emission. A lowest noise emission was recorded at the 0.5% graphene oxide nanofluid condition which is less than 75 db. Also, high accuracy machining operation was observed at the higher concentration of 0.5% wt. with a circularity and cylindricity value less than 0.010 mm deviation.
[0025] The analytical results indicate that a concentration of 0.5% wt. of graphene oxide (GO) nanofluid exhibits enhanced performance in relation to tool wear, surface roughness, cutting temperature, cutting power, noise emission and high dimensional component accuracy (cylindricity and circularity). Therefore, this concentration is advised for further improving the machinability in the hard turning process of AISI D2 steel in industry.
[0026] While the invention has been described and shown with reference to the preferred embodiment, it will be apparent that variations might be possible that would fall within the scope of the present invention.
BRIEF DESCRIPTION OF DRAWINGS
[0027] So that the manner in which the above-recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may have been referred by embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
[0028] These and other features, benefits, and advantages of the present invention will become apparent by reference to the following text figure, with like reference numbers referring to like structures across the views, wherein:
[0029] Figure 1: Methodology followed for preparation of Nanofluid;
[0030] Figure 2: Nano MQL system set up for CNC turning process (1- Air compressor, 2-Relief valve, 3- Pressure gauge, 4- Solenoid Valve 5-Mixing chamber, 6-MQL flow rate adjustment valve,7- Moisture control valve, 8-Pressure gauge, 9- Oil reservoir 10-MQL hose pipe for nozzle1, 11-MQL nozzle 1,12- MQL hose pipe 2, 13-MQL nozzle 2, 14- Cutting insert, 15-Tool holder, 16- Turret head, 17-Workpiece, 18- Head stock, 19- Tail stock.
DETAILED DESCRIPTION OF THE INVENTION
[0031] While the present invention is described herein by way of example using embodiments and illustrative drawings, those skilled in the art will recognize that the invention is not limited to the embodiments of drawing or drawings described and are not intended to represent the scale of the various components. Further, some components that may form a part of the invention may not be illustrated in certain figures, for ease of illustration, and such omissions do not limit the embodiments outlined in any way. It should be understood that the drawings and the detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the scope of the present invention as defined by the appended claim.
[0032] As used throughout this description, the word "may" is used in a permissive sense (i.e. meaning having the potential to), rather than the mandatory sense, (i.e. meaning must). Further, the words "a" or "an" mean "at least one" and the word "plurality" means "one or more" unless otherwise mentioned. Furthermore, the terminology and phraseology used herein are solely used for descriptive purposes and should not be construed as limiting in scope. Language such as "including," "comprising," "having," "containing," or "involving," and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers, or steps. Likewise, the term "comprising" is considered synonymous with the terms "including" or "containing" for applicable legal purposes. Any discussion of documents, acts, materials, devices, articles, and the like are included in the specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention.
[0033] In this disclosure, whenever a composition or an element or a group of elements is preceded with the transitional phrase "comprising", it is understood that we also contemplate the same composition, element, or group of elements with transitional phrases "consisting of", "consisting", "selected from the group of consisting of, "including", or "is" preceding the recitation of the composition, element or group of elements and vice versa.
[0034] The present invention is described hereinafter by various embodiments with reference to the accompanying drawing, wherein reference numerals used in the accompanying drawing correspond to the like elements throughout the description. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiment set forth herein. Rather, the embodiment is provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. In the following detailed description, numeric values and ranges are provided for various aspects of the implementations described. These values and ranges are to be treated as examples only and are not intended to limit the scope of the claims. In addition, several materials are identified as suitable for various facets of the implementations. These materials are to be treated as exemplary and are not intended to limit the scope of the invention.
[0035] The present invention relates to hard turning machinability process by Graphene Oxide ased nano-lubricant through multi-nozzle injection MQL system.
[0036] The present study aims to suggest a sustainable nano lubricant for enhancing the process of CNC turning of hardened AISI D2 steel. Graphene oxide nanoparticles are employed in the synthesis of nano lubricants, whereas in the production of nanofluids, Graphene oxide nanoparticles are uniformly dispersed into spring oil (LRT 30). The concentration of nanoparticles in the base fluid leads to an increase in its thermal carrying coefficient, resulting in enhanced cooling at the cutting zone and a progressive improvement in overall machining performance. Moreover, the existence of an excessive amount of nanoparticles within the base fluid occasionally leads to heightened friction between the cutting tool and the workpiece, resulting in surface degradation. Consequently, the cutting temperature escalates because of this friction, thereby causing deterioration of the tool substrate as well. In order to address this issue, a comprehensive investigation was conducted on the impact of six different concentrations of graphene oxide nanofluid on the hard turning operation of AISI D2 steel. This invention involves the preparation of six wt.% concentrations of Graphene oxide (GO) nanofluids. The performance of these nanofluids during hard turning operation is studied, and the optimal concentration for using Graphene oxide (GO) nanofluids in hard turning operations is recommended to machinists and the industry. This recommendation aims to enhance the efficiency of machining processes and promote green and sustainable machining applications.
[0037] The study focused on analysing the machining properties of AISI D2 hardened steel in a newly created NFMQL (Nanofluid MQL) environment. This was achieved by utilising Multi-layer CVD coated carbide inserts with wiper finishing shape. The output responses under investigation encompass tool wear, surface roughness, cutting temperature, cutting power, and cutting noise assessment. The studies were carried out using a CNC lathe on AISI D2 hardened steel (55 ± 1 HRC). The primary applications encompass Blanking Dies, Forming Dies, Coining Dies, Slitting Cutters, Heading Tools, Long Punches, Forming Rolls, Edging Rolls, Master Tools, Beading Rolls, Intricate Punches, Extrusion Dies, Drawing Dies, Lamination Dies, Thread Rolling Dies, Shear Blades, Burnishing Tools, Gauges, Knurls, and Wear Parts. The turning process involved the use of cutting tools supplied by WIDIA Ltd, namely the ISO-designated CNMG 120408FW coated carbide (MT-CVD/ CVD-TiN-TiCN-Al2O3) with grade WK05CT. The tools are coated with three layers of TiN-TiCN-Al2O3, which were produced using the chemical vapour deposition (CVD) process. These tools possess a wiper finishing shape, which is designed to enhance the surface quality. The cutting speed (v) of 140 m/min, feed rate (f) of 0.1mm/rev, and depth of cut (d) of 0.2 mm were chosen based on published research and the recommendations of the tool manufacturer. All studies done during the hard turning operation of AISI D2 steel under graphene oxide (GO) nanofluid MQL environment maintained fixed cutting parameters for all six nanofluid concentrations. Experiments are conducted three times for each concentration of nanofluid to prevent any unforeseen mistake percentages. The average end result value is then calculated for all the trials. The machining area was supplied with a graphene oxide-based nanofluid using a Multi-Nozzle (MQL) system operating at a 6-bar air pressure, 30 mm stand-off distance and a coolant flow rate of 50 ml/hr. This was achieved through the use of double nozzles.
[0038] The size and elemental analysis of graphene oxide nanoparticles were analysed using FESEM and EDS techniques. Based on the research conducted using a Finite element scanning electron microscope (FESEM), the average size of the nanoparticles was determined to be 18 nm. Additionally, the existence of Carbon(C) and oxygen (O) elements in the sample was identified using energy-dispersive spectrometry (EDS) analysis, with percentages of 96.5 percent and 3.5 percent, respectively. Prior to nanofluid production, the graphene oxide (GO) nanoparticles undergo a preheating process for a duration of 3 hours at a temperature of 200℃ in order to eliminate moisture from the nanoparticles. Subsequently, graphene oxide (GO) nanoparticles are uniformly distributed into LRT 30, spring oil composed of iron and aluminium. This current innovation involves the preparation and development of six different concentrations of graphene oxide (GO) based nanofluids, namely 0.05%wt, 0.1%wt, 0.2%wt, 0.3%wt, 0.4%wt, and 0.5%wt. In order to achieve pre-dispersing, graphene oxide (GO) nanoparticles were introduced into the base oil LRT 30. To facilitate the immediate mixing of graphene oxide (GO) and LRT 30 oil, a mechanical stirrer was employed for a duration of 30 minutes at a speed of 1400 rpm for all concentrations. Nanofluids are created using a two-step method. Initially, nanoparticles are dispersed in the base oil. Subsequently, nanofluids with concentrations of 0.05%wt., 0.1%wt., 0.2%wt., 0.3%wt., 0.4%wt., and 0.5%wt. are mixed in a magnetic stirrer for durations of 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, and 9 hours, respectively. To prevent nanoparticle clustering in base oil, nanofluids with concentrations of 0.05%wt, 0.1%wt, 0.2%wt, 0.3%wt, 0.4%wt, and 0.5%wt were subjected to ultrasonication for durations of 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, and 8 hours, respectively. The approach for preparing nanofluids is illustrated in Figure 1. The hard turning operation was performed on hardened AISI D2 steel using multilayer CVD coated carbide tools with wiper finish geometry. The specified fixed input parameters included a cutting speed (v) of 140 m/min, feed rate (f) of 0.1mm/rev, and depth of cut (d) of 0.2 mm. To ensure accuracy, each experiment was repeated three times. The average results were then calculated for various parameters including tool wear, surface roughness, cutting temperature, cutting power, and cutting noise.
[0039] Multi nozzle application (Double nozzle) was employed to spray the developed nanofluids with high pressure into the cutting zone from two directions. 1st nozzle was kept vertically facing towards the tool- workpiece contact zone and the second nozzle was faced toward the principal flank face of the cutting tool with an angle of 45° from the cutting tool holder axis as shown in Figure. 2. For each nozzle continuous coolant flow (Graphene oxide Nano-Fluid) of 50 ml/hr was maintained with 6 bar pressure and 30 mm standoff or nozzle distance through an MQL system. The components and the configuration of the MQL system are demonstrated in Figure.2.
[0040] In order to enhance the machinability of AISI D2 steel during the turning process, an initial experiment was conducted to ascertain the ideal concentration of nanofluid. The investigation on tool wear exhibited a direct correlation between the concentration of nanoparticles in the base fluid and the gradual reduction in flank wear. As the concentration of graphene oxide (GO) nanofluid increases from 0.05% wt. to 0.5% wt., there is a gradual reduction in average tool wear was noticed. The minimum tool wear is seen when the concentration of graphene oxide (GO) nanofluid is 0.5% by weight. At the highest concentration of nanofluid, a reduction in tool wear of 32.14% was observed. At 0.5% of GO nanofluid condition lowest tool wear observed which is very low according to hard turning concern. The enhanced capacity to cool and lubricate in the cutting zone region may be due to the remarkable thermal conductivity of the nanofluid based on graphene oxide, which is paired with Mult-nozzle injection in the MQL setup. An investigation was carried out to assess the state of the tool following machining in environments with GO concentrations of 0.05% and 0.5%. Moreover, during the examination of the cutting temperature values, a significant reduction in the temperature of the cutting zone was seen at the highest concentration (0.5%) of graphene oxide (GO) nanofluid. According to the results, it has been demonstrated that a higher concentration of nanoparticles in the base fluid causes a gradual increase in thermal conductivity. The observed rise in temperature contributes to a significant reduction in the cutting zone during hard turning operations. The empirical evidence suggests a persistent reduction in temperature of 37.67% when the nanoparticle concentration in the base oil LRT 30 escalates from 0.05% to 0.5%. The examination of the findings showed a significant improvement in the quality of the surface due to an enhanced cooling and lubrication strategy. The highest recorded surface polish value obtained when the weight percentage was 0.05%, far lower than the needed level for hard turning. The surface quality get improved when the concentration of GO nanofluid was 0.5% wt., leading to a reduction in surface roughness by 30.21% compared to the surface roughness observed with a nanofluid concentration of 0.05% wt. The power consumption was found to be the lowest while using a concentration of 0.5% wt. of GO Nanofluid, in comparison to all other concentrations. The application of a 0.5% concentration of GO nanofluid resulted in a reduction of approximately 32.08% in cutting power, compared to the lowest concentration of GO nanofluid (0.05%). The increased lubrication at the highest concentration resulted in a significant decrease in friction between the tool tip and workpiece, leading to a reduction in cutting force and thus decreasing power consumption and reduction in noise emission. A lowest noise emission was recorded at the 0.5% graphene oxide nanofluid condition which is less than 75 db. Also, high accuracy machining operation was observed at the higher concentration of 0.5% wt. with a circularity and cylindricity value less than 0.010 mm deviation.
[0041] The analytical results indicate that a concentration of 0.5% wt. of graphene oxide (GO) nanofluid exhibits enhanced performance in relation to tool wear, surface roughness, cutting temperature, cutting power, noise emission and high dimensional component accuracy (cylindricity and circularity). Therefore, this concentration is advised for further improving the machinability in the hard turning process of AISI D2 steel in industry.
[0042] This innovation presents the first-ever method for cooling and lubricating in the hard turning operation of hardened AISI D2 Steel, specifically utilizing Graphene oxide (GO) + LRT 30. Prior to the turning process, no nanofluid solution with a substantial concentration was given for enhancing the machinability of AISI D2 steel. This invention proposes the optimal concentration of graphene oxide nanoparticles in the base oil LRT 30 to enhance the machining application of hardened steel, hence introducing a distinctive approach.
[0043] CBN, PCBN, and Ceramic tools are commonly investigated for the machining of hard materials, but their acquisition is expensive, resulting in an overall rise in manufacturing costs. The use of commercially available low-cost multi-CVD coated carbide tools with wiper finishing geometry is employed in this innovation. Prior to this study, CVD coated tools were utilized for hard machining operations. However, the utilization of wiper finishing geometry with CVD coated carbide tools has not been previously employed and is being utilized for the first time in this present research.
[0044] Tool wear and surface roughness are widely researched reactions in machining applications. However, this innovation also thoroughly examines cutting temperature, power consumption, and cutting noise, in addition to tool wear and surface roughness. The current research examination for high dimensional accuracy product has been conducted through cylindricity and circularity, which is also a notable response study for component accuracy. The cutting temperature has a direct correlation with tool wear and surface roughness, necessitating the implementation of a suitable cooling lubrication strategy for effective management. This innovation uses a double nozzle mist flow (Multi nozzle assisted Nanofluid MQL) of coolant (GO + LRT 30) nanofluid to regulate the temperature in the cutting zone. The implementation of this method has resulted in a notable decrease in temperature generation during machining. Power consumption is a crucial determinant of sustainability that significantly impacts the whole cost of manufacturing. This innovation proposes the use of a certain concentration of nanofluid (GO + LRT 30) to effectively reduce power consumption during harsh machining processes. The presence of cutting noise is directly linked to the wear of the tool and the friction that occurs between the tool and the workpiece during the machining process. In this study, it was determined that the implementation of a suitable lubrication approach utilizing a nanofluid containing (GO + LRT 30) at the specified concentration may effectively reduce the undesirable cutting noise, hence enabling industries to effectively manage noise pollution. In order to address the health concerns of workers and operators, it is imperative that the level of sound reduction does not exceed 85dB. The present study has documented a notable decrease in cutting noise with the use of a nanofluid consisting of (Graphene oxide (GO) + LRT 30).
[0045] This innovation primarily focuses on the development of high-precision products with better surface quality. Additionally, it aims to reduce the entire manufacturing cost of the product or industry while considering sustainability and environmental factors. The idea in question is widely regarded as a promising cooling lubrication approach that holds promise for the advancement of green and sustainable industrial processes.
[0046] The current innovation is novel and not used yet for any machining applications.
[0047] The technical differences between the conventional and current process are technically compared in Table 1.
Table 1: Technical differences in between conventional and current process
Conventional/existing process Current process
Lower cutting performance Relatively higher cutting performance
Tool life is minimum The tool life is more
Higher production cost Respectively lower production cost
Hazardous to worker's and operator's health No bad health impact on workers and operators
Environmental and sustainability concerns Sustainable and environment-friendly
[0048] The innovative characteristics of this invention are as follows:
- The use of Nano-Fluid MQL (Graphene oxide (GO)+ LRT 30) cooling technology is an innovative principle that has not before been employed in the context of machining operations.
- This invention proposes a new concentration of Graphene oxide nanofluid for machining applications which has not been previously used.
- Furthermore, the trials are conducted using inexpensive multi-CVD coated carbide tools with wiper finishing geometry. This approach has the potential to reduce overall machining costs and improve product quality by achieving a superior finished product.
[0049] Various modifications to these embodiments are apparent to those skilled in the art from the description and the accompanying drawings. The principles associated with the various embodiments described herein may be applied to other embodiments. Therefore, the description is not intended to be limited to the 5 embodiments shown along with the accompanying drawings but is to be providing the broadest scope consistent with the principles and the novel and inventive features disclosed or suggested herein. Accordingly, the invention is anticipated to hold on to all other such alternatives, modifications, and variations that fall within the scope of the present invention and appended claims. , C , Claims:CLAIMS
We Claim:
1) A hard turning machinability process using graphene oxide-based nanofluids, comprising:
- preparing a nano-lubricant by dispersing graphene oxide (GO) nanoparticles in a base oil (LRT 30);
- employing the nano-lubricant in a multi-nozzle minimum quantity lubrication (MQL) system to spray at a controlled flow rate into the cutting zone;
- using the nanofluid for hard turning of hardened AISI D2 steel with carbide tools having a wiper finishing geometry;
- wherein the nanofluid concentration comprises six weight percentages of graphene oxide, ranging from 0.05% wt. to 0.5% wt., to optimize machining performance.
2) The process as claimed in claim 1, wherein the graphene oxide nanoparticles are preheated at 200°C for 3 hours prior to dispersion to eliminate moisture.
3) The process as claimed in claim 1, wherein the concentration of graphene oxide nanofluid is optimized for minimizing tool wear, reducing surface roughness, decreasing cutting temperature, and enhancing tool life, particularly at a concentration of 0.5% wt.
4) The process as claimed in claim 1, wherein a multi-nozzle system is configured with one nozzle directed towards the tool-workpiece interface and another directed at a 45° angle towards the principal flank face of the tool, each spraying nanofluid at 6-bar pressure and a flow rate of 50 ml/hr.
5) The process as claimed in claim 1, wherein the cooling and lubricating effect of the graphene oxide nanofluid significantly reduces cutting temperature, tool wear, and power consumption during the hard turning of AISI D2 steel.
6) The process as claimed in claim 1, wherein the reduction in tool wear is directly correlated with the concentration of graphene oxide nanoparticles, resulting in a 32.14% reduction at a 0.5% wt. concentration.
7) The process as claimed in claim 1, wherein the nanofluid enhances the surface quality by reducing surface roughness by up to 30.21% at a concentration of 0.5% wt., as compared to lower concentrations.

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