INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING AND TECHNOLOGY (IJMET)

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1 INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING AND TECHNOLOGY (IJMET) International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 ISSN (Print) ISSN (Online) Volume 3, Issue 2, May-August (2012), pp IAEME: Journal Impact Factor (2011): (Calculated by GISI) IJMET I A E M E EXPERIMENTAL INVESTIGATION ON RESPONSES IN TURNING OF ALUMINIUM WITH CARBIDE TIPPED TOOL AT DIFFERENT COOLANT CONDITIONS K.Dharma Reddy Research Scholar and Assistant Professor *Dr.P.Venkataramaiah Associate Professor Department of Mechanical Engineering Sri Venkateswara University College of Engineering, Tirupati, Andhra Pradesh, India *Corresponding author ABSTRACT Turning is a widely used metal removal process in manufacturing industry that involves generation of high cutting forces and temperature. Lubrication becomes critical to minimize the effects of these forces and temperature on life of cutting tool and, Surface finish of work. In metal industry, the use of coolant has become more problematic in terms of both workpiece quality, employee health and environmental pollution. In the present work, chip tool interface temperature was measured for three different lubricant conditions such as dry, wet, and Minimum quantity lubrication. Later has been proved to be a feasible alternative to the conventional cutting fluid system. In the present work 10% boric acid by weight mixed with base oil SAE 40 is used as a MQL in turning process. Variations in cutting force, cutting temperature, chip thickness and surface roughness are studied under different machining and coolant conditions. The results indicate that there is a considerable improvement in machining performance under MQL machining compared to dry and wet machining. Keywords: Turning,dry, wet, MQL, Temperature 1. INTRODUCTION A new alternative to traditional use of cutting fluids is Minimum Quantity Lubricant (MQL), also known as Near Dry Machining (NDM) or semi-dry machining. MQL uses a very small quantity of lubricant delivered precisely to the cutting surface. 189

2 Improvements in chip recycling, reduction of electricity consumption, increased tool life, a "greener environment, and a decrease of machine maintenance due to contamination by coolant are very much essential, to the metal cutting industry. Different work piece materials with different property and microstructure have different effect on cutting tool performance. No general equation can be available to estimate the tool life for a given tool grade, cutting condition and work piece material. In this work, carbides tipped tools are used in machining of Aluminum work piece under Dry, Wet and MQL conditions. Different researchers investigated the influence of cutting fluid in cutting of metals is reviewed as follows. Itoigawa, etal [1] are investigated the effects of MQL in intermittent turning of AL. Liang Liang, etal [2] used the finite difference solution and an inverse procedure to determine the tool-chip interface temperature. A.Liljerehn, etal [3] used analytical model for prediction of heat generation in the primary and secondary deformation zones, results obtained from finite element simulations are compared with temperatures measured using IR-CCD camera. F. Akbar,etal [4] investigated the tool-chip interface temperature and Heat Partition in High-speed Machining. H. Zhao, etal [5] The effects of the heat sink intensity, heat sink distance from the tool-chip interface, and heat sink area on the tool-chip interface temperature have been investigated. It was found that the internal cooling with a heat sink in the cutting tool could greatly affect the tool-chip interface temperature. R. M'Saoubi, etal[6] found a new method for cutting tool temperature measurement using ccd infrared technique..junzhan Hou, etal[7] measured the mean flank temperature through mounting two K-type thermocouples in work piece of AM50A magnesium alloy. W.Grzesik,etal [8] A finite difference method was proposed to model the effect of a variety of tool coatings on the magnitude and distribution of temperatures through the tool-chip contact region and the coating/substrate boundaries. J.-L. Battaglia etal[9] The temperature at the tip of a tool used in a turning process are estimated from temperature measurements in an interior point of the tool insert.j.c.outeiro, etal[10] presents the experimental analysis of the temperature distribution in the threedimensional cutting process. H. A. Kishawy[11] investigated experimentally the effects of different process parameters on the cutting edge temperature during high speed machining of D2 tool steel using polycrystalline cubic boron nitride (PCBN) tools. H. A. Kishawy, etal[12] investigated the effect of process parameters, tool geometry and edge preparation on the contact mechanics at the chip/tool interface.haj Elmoussami[13] presents an experimental technique for the estimation of the average temperature on the cutting edge of each insert in a milling tool. Tien-Chien Jen, etal [14] analysed interrupted cutting tool temperatures. Lorraine Olson etal [15] estimated the tool/chip interface temperatures for on-line tool monitoring.after the review,this work concentrated on study of response, like temperature, surface finish and force in turning of Aluminium of different lubricating conditions. 2. Methodology 2.1 fluids and lubricants During the metal cutting process heat is generated due to deformation of the material ahead of the tool and Friction at the tool point. Heat generated due to friction can readily be reduced by using a lubricant.in the pursuit of environmental, profit, safety, and convenience a number of alternatives to traditional machining are currently under development. Dry machining has been around for as long as traditional machining but has seen a recent surge in interest as more people are realizing the true cost of cutting fluid management. There are some alternatives to replace cutting fluids such as dry 190

3 machining, minimum quantity lubricant and liquid nitrogen technology.mql is alternative to traditional use of cutting fluids. As the name implies MQL uses a very small quantity of lubricant delivered precisely to the cutting surface. Often the quantity used is so small that no lubricant is recovered from the piece. Any remaining lubricant may form a film that protects the piece from oxidation or the lubricant may vaporize completely due to the heat of the machining process. With the large volumes of cutting fluid used in traditional machining, misting, skin exposure and fluid contamination are problems that must be addressed to assure minimal impact on worker health. In the present work, boric acid is used as coolant, it is one of the most popular solid lubricants and has excellent lubrication properties without calling for expensive disposal techniques. The most important characteristics of boric acid for use as a lubricant are that it is readily available in cheap and environmentally safe. Several studies related to the lubrication properties of boric acid are carried out over the past several decades. This work also focused on the performance of boric acid in high temperature applications. The studies indicated that boric acid is unique layered intercrystalline structure makes it a very promising solid lubricant material because of its relatively high load carrying capacity and low steady state friction coefficient (0.02). 2.2 MATHEMATICAL MODEL OF SHEAR PLANE TEMPERATURE IN ORTHOGONAL CUTTING In the present work to check the validity of experimental results the following mathematical model has been used. The temperature rise at the shear plane can be approximately estimated by assuming a thin zone model of metal cutting and by assuming a uniform rise of temperature all over the shear plane. Losses due to conduction may be taken into account by multiplying the heat generated with a factor. Let Es be the energy per unit volume dissipated at the shear plane, then λ Es θs = + θi (1.1) J Cw Where θs = Temperature at shear angle zone) θi = Initial temperature of work piece (not consider at primary λ = factor representing the fraction of heat retained by the chip J = heat equivalent of mechanical energy = 4.2 N-m/cal = density of work material Cw = specific heat of work material The value of Es is given by Fs.Vs Es = N-m/cm³ (1.2) b.t.v 191

4 Where Fs is the shear force in N on the shear plane and Vs is the shear velocity in m/min, b is the width of cut in mm, t is uncut chip thickness in mm and V is the cutting velocity in m/min. Otherwise K cosα Es = N/mm² (1.3) SinØ cos (Ø α) K = yield strength of material in N/mm² r cosα (1.4) TanØ = 1- r sinα When it is rake angle of tool (It is considered as10 ) Chip thickness ratio (r) = Depth of cut (d) Chip thickness (tc) Cosα Shear strain on the shear plane εs = (1.5) SinØ cos (Ø α) Using above models the cutting parameters are calculated as shown in table.8.the results obtained from mathematical model are compared with experimental results. (See Table. 8 and figure.10) 3. EXPERIMENTAL WORK The Experiment is conducted at different conditions like dry, wet and Minimum lubricant (Boric acid 10% with base oil SAE40) for different cutting speeds. The cutting temperature, cutting force,chip thickness,surface finish are measured and recorded. Setup for measuring temperature and cutting force is shown in Fig.1and fig

5 Fig.1 Experimental setup for measuring chip-tool interface Temperature Fig.2 Tool lathe Dynamometer measures force Table: 1 Experimental conditions 1 Type of Machine Lathe full details 2 Tool used Carbide insert 3 Work-piece material Aluminium fluid used Mineral oil and SAE Measurement of responses in turning (i)measurement of forces The forces acting on the tool have been measured using an Kistler Dynamometer.The dynamometer senses all the three forces viz. feed force(fx),cutting force(fy), and thrust force (Fz) generated during the cutting. Values of these forces are recorded while turning(table.7.1,7.2,7.3). (ii)measurement of surace finish The surface quality of the machined surface has been measured using Mitutoyo surface roughness tester. The tester consists of a flat table, tracer with drive unit and recorder. The machined flat surface to be tested was kept on the table by adjusting the tracer arm. The stylus traces the machined surface in the direction of feed motion. The stylus moves over the surface of work piece for a limited length of 0.8mm. The arithmetic mean deviation in micrometers was recorded as in Table.6. (iii)measurement of chip thickness Chip thickness was measured with out side micrometer, of MITUTOYO more precise measuring instrument (Table.5) 4.Experimental Results The experimental values for various parameters are recorded and graphs are plotted as follows. 193

6 Table 1 Experimental values of temperature at dry condition. Depth of cut = 1.0mm speed (m/min)(rpm) (mm/rev) 21 (228) 1 34 (360) (450) (580) ( 740) (800) 0.1 Temperature ( C) Length of Cut (mm) Table 2 Experimental values of Fig.1 Variation of cutting temperature at Wet condition Temperature with Length of Cut under dry condition Speed (m/min) (RPM) (mm/rev) 21 (228) 1 34 (360) (450) (580) ( 740) (800) 0.1 Temperature( C) Length of Cut (mm) Table 3 Experimental values of Temperature with temperature in MQL condition. Fig.2 Variation of cutting Length of Cut under Wet Condition Speed m/min (RPM) (mm/rev) 21 (228) 1 34 (360) (450) (580) ( 740) (800) 0.1 Temperature ( C) Length of Cut(mm) Fig. 3 Variation of cutting Temperature with Length of Cut under MQL condition 194

7 Table 4 Experimental Values of Temperature at shear Zone for different conditions. Dry Speed m/min (RPM) (mm/rev) Average Temperature ( C) Dry Wet MQL 21 (228) (360) (450) (580) (740) (800) MQL Table 5 Experimental Values of Fig.4 Variation of cutting Chip thickness for depth of cut=1mm Temperature with speed under dry, wet, MQL conditions Wet Speed m/min (RPM) (mm/re v) Average Chip Thickness(mm) MQL Dry Wet DRY WET 21 (228) (360) (450) (580) ( 740) (800) Table 6 Experimental values of Surface Roughness different speeds and feed rates at Dry, Wet and MQL condition. Depth of cut = 1.0mm Speed m/min m/min (RPM) (mm/rev) Surface Roughness (µm) Dry Wet MQL Fig.5 Variation of Chip thickness with under Dry, wet, MQL conditions MQL MQL WET 21 (228) (360) (450) (580) ( 740) (800) DRY Fig.6 Variation of Surface Roughness under dry, wet & MQL condition 195

8 Table 7.1 Experimental values of cutting forces at Dry condition. Depth of cut = 1.0mm Speed m/min(rpm) (rev/min) 21 (228) 1 34 (360) (450) (580) ( 740) 0.2 X (kgf) Y (kgf) Thrust Z (kgf) Y X Z 76 (800) Table 7.2 Experimental values of cutting at Wet condition Fig. 7 Variation of with forces rate under dry condition Depth of cut = 1.0mm Speed Thrust Y m/min(rpm) (rev/min) X (kgf) Y (kgf) Z (kgf) X Z Table 7.3 Experimental values of cutting forces MQL condition Fig.8 Variation of with rate under Wet Condition Depth of cut = 1.0mm Speed m/min(rpm) (rev/min) X (kgf) Y (kgf) Thrust Z (kgf)

9 Theoretical Y X Experimental Z Fig.9 Variation of with rate under MQL condition Fig.10 Variation of cutting Temperature at shear zone for different Speeds and feeds Table 8 Theoretical calculations of temperature for Aluminium Speed tc r tanø Ø Es εs θs m/min(rpm) (rev/min) (mm) (N/mm²) C 21 (228) (360) (450) (580) ( 740) (800) DISCUSSIONS AND CONCLUSIONS forces, tool temperature, chip formation and surface roughness of work piece during machining under the MQL (Boric Acid mixed with SAE oil) are compared with dry and wet machining using carbide tipped cutting tool. The experimental results reveal that the use of MQL is advantageous over dry and wet machining. This lubrication has improved the process performance by reducing the cutting forces and temperature. It is due to unique bond characteristics, MQL machining reduces chip thickness considerability over dry turning that are favorable for chip formation in compare to dry machining. And also the chip-tool interface temperature is reduced depending upon the level of process parameters. With increase in speed resulted decrease in cutting forces and machined surface temperature. This reduction in temperature attribute to higher metal removal rate which carried more heat by chip. 197

10 However, the present work may be extend to address the variability of machining parameters in attempt to maximize tool life while optimizing the machined surface quality using mists application. We can also use the analysis of variance (ANOVA) to check the validity of proposed parameters and also their percentage contributions. Further, ranges of cutting speed, feeds and depth of cut for machining harder materials may be investigated using MQL. Acknowledgements: Authors would like to acknowledge the technical staff and P.G students E.Madhusudhana Rao, S.Saritha of Mechanical Engineering Department,Sri Venkateswara University College of Engineering, Tirupati for their help in completing this research work. REFERENCES [1] F.Itoigawa,D.Takeuchi,T.Nakamura & T.H.C.Childs, Experimental study on lubrication mechanism in MQL intermittent cutting process, Machining Science and Technology, Volume 11, Issue 3, 2007, pages ,(T&F). [2] Liang Liang, Yanming Quan and Zhiyong Ke, Investigation of tool-chip interface temperature in dry turning assisted by heat pipe cooling, The International Journal of Advanced Manufacturing Technology, Volume 54, Numbers 1-4,April 2011, pp (9),Springer. [3] A. Liljerehn, V. Kalhori, and M. Lundblad, Experimental studies and modeling of heat generation in metal machining, Machining Science and Technology: An International Journal, Volume 13, Issue 4, 2009(T&F). [4] F. Akbar,P. T. Mativenga and M. A. Sheikh, An Investigation of the Tool-Chip Interface Temperature and Heat Partition in High-speed Machining of AISI/SAE 4140 Steel with TiN-coated Tool, Proceedings of the 35th International MATADOR Conference 2007, 10, [5]H. Zhaoa, G. C. Barberb, Q. Zoub & R. Gub, Effect of Internal Cooling on Tool-Chip Interface Temperature in Orthogonal, Tribology Transactions, Volume 49, Issue 2, 2006, pages [6] R. M'Saoubi,J.L.Lebrun & B.Changeux, A new method for cutting tool temperature measurement using ccd infrared technique: influence of tool and coating, Machining Science and Technology: An International Journal,Volume 2, Issue 2, 1998, pages [7] Junzhan Hou, Ning Zhao & Shaoli Zhu, Influence of Speed on Flank Temperature during Face Milling of Magnesium Alloy, Materials and Manufacturing Processes, Volume 26, Issue 8, 2011, pages [8] W.Grzesik, M.Bartoszuk & P.Nieslony, Finite difference method-based simulation of temperature fields for application to orthogonal cutting with coated tools, machining science and technology: an international journal volume 9, issue 4, 2005, pages [9] J.-L.Battaglia & J.-C.Batsale, Estimation of heat flux and temperature in a tool during turning, Inverse problems in Engineering Volume 8,Issue 5,2000. Pages [10] J. C. Outeiro, A. M. Dias & J. L. Lebrun, Experimental Assessment of Temperature Distribution in Three Dimensional Process, Machining Science and Technology: An International Journal Volume 8, Issue 3, 2004, pages [11] H.A. Kishawya,An Experimental evaluation of cutting temperatures during high speed machining of hardened d2 tool steel, Machining science and technology: An international journal volume 6, issue 1, 2002, pages

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