Analysis of Cutting Forces in High Speed Turning of Inconel 718 by using Ceramic Tools

Transcription

1 International Conference on Multidisciplinary Research & Practice P a g e 17 Analysis of Cutting Forces in High Speed Turning of Inconel 718 by using Ceramic Tools Ganesh. S. Sonawane 1 1 PG Student, Mechanical Engineering Department, S.S.G.M.C.O.E, Shegaon, M.S. India Chinmay.V.Patil 2 2 Assistant Professor, Mechanical Engineering Department, S.S.G.M.C.O.E, Shegaon, M.S. India Raju. S. Pawade 3 3 Associate professor, Dept. of Mechanical Engineering, Dr. Babasasheb Ambedkar Technological University, Lonere, M.S. India Abstract- The paper presents an experimental investigation of cutting forces of super alloy Inconel 718 during high speed turning using advanced ceramic grade KYS25 and KYS3 inserts with three different nose radii. The effect of machining parameters on cutting forces was investigated in dry machining. Firstly varying one input parameter speed v=1-45m min -1, f=.25mm rev -1 and d=.75 is kept constant. Second varying f=.5 to.4 mmrev-1, Vc=25-mmin -1 and d=.75mm is kept constant, Finally varying d= mm,v=25 mmin -1 and f=.25mmrev -1 is kept constant. The result show that KYS3 rhomboid shaped insert is good surface finish and lower cutting forces in between v=1 - mmin-1 as compared to KYS25 insert. Keywords: High speed machining, Advance ceramic tools, Cutting force, Inconel 718. N I. INTRODUCTION ickel based alloy, Inconel, 718 is extensively used in an aerospace engine, gas turbine, space vehicle, rocket engine, nuclear reactor, submarine and petrochemical devices [1].The components assembled in these devices are subjected to extreme stress and temperature condition. This necessitates the component with high degree surface integrity which is vital need for better performance, reliability and longevity of the machined parts during service. The machining forces have an important share in the generation of stresses and temperature in the machined surfaces and hence, it is important to know the machining parameters, which reduce the cutting forces and generate favorable surface characteristics [2]. Inconel 718 is machined using coated carbide, ceramic and CBN cutting tools. Due to short life of carbide cutting tools, the ceramic inserts are finding promising result while machining these alloys. These are possible due to improved properties of the ceramic tools such as fracture strength, toughness, thermal shock resistance, hardness and wear resistance. These developments made the ceramic tools to withstand temperature produced in high speed cutting of Inconel 718.Besides reduction in cutting forces and improved surface finish as compared to that of plain and coated carbides makes them suitable for machining at higher cutting speeds. [3].The paragraph below highlights the few prominent studies of machinablity of Inconel 718 using ceramic insert. Narutaki et al [4] observed that the SiC-whiskered ceramic insert showed best performance in respect of notch wear at cutting speed under 3m/min and Tic added alumina ceramic tool showed small tool wear as compared to carbide tools. Ezugwu [5] used pure oxide and mixed oxide ceramic tools to study the extent of surface damage on machined surface under optimum cutting condition. A rhomboid shaped and round inserts were used during experimentation. Machining with the mixed oxide ceramic tools generally produced better surface finish than with oxide ceramic because of their improved hot hardness, fracture toughness and wear resistance. Li and wang [6] focused on cutting speed influenceon tool wear and tool life. They reported that the Sialon grade ceramic insert with square and round shape proved better for high speed machining of Inconel 718. Coelho et al [7] studied the performance of similar insert subjected to modification on edge geometry form on tool wear, surface roughness and temperature during high speed turning of speed nickel based alloy. They found that round inserts made of alumina based ceramic C5 are the best in terms of tool wear and flank wear. Ceramic tools shown lower temperature on the rake face during machining compared to PCBN. Ezugwu et al [8] focused their study on cutting force and tool wear during machining of Inconel 718 using round shaped whisker reinforced ceramic insert. They observed that lower forces are generated at high coolant supply pressure due to improved cooling and lubrication at cutting interfaces. Nalbant [9] discussed the effect of cutting speed on tool wear and tool life when machining of Inconel 718 using square and round ceramic insert. He observed that square type inserts shows good performance compared to round inserts at low main cutting force are obtained square insert SNGN and highest cutting forces are observed on RNGN 127 ceramic tools, which depends on tool geometry. Bushly [11] experimentally observed the effect of cutting parameters and coolant condition on damage to the machined surface. cutting speeds and round type insert are good at high cutting speeds. Muammer and Altin [1] studied the effect of cutting speed and edge geometry on cutting force. They reported that The literature review shows that the work undertaken using advance ceramic tool under dry cutting condition is inadequate. In this investigation super alloy Inconel 718 is machined by using advanced SIALON grade ceramic CVD coating KYS25 and KYS3 rhomboid shaped inserts having different nose radii. The main objective of this research is to study the influence of machining parameters on cutting force using experiment Volume I Issue VII IJRSI ISSN

2 International Conference on Multidisciplinary Research & Practice P a g e 18 and to find the suitable tool geometry and the optimal cutting conditions in order to achieve higher mach inability. II. EXPERIMENTAL SET UP Machining tests are carried out on a CNC turning lathe(make-micromatic Model-Jobber XL) with capacity of 5.7 KW and maximum spindle rpm of 5.The three force components F c, F t and F f are measured online during turning of Inconel 718 with a sensitive three component kistler dynamometer (Model-9257 BA) with built in charge amplifier. Data acquisition was made through the charge amplifier and a computer using dynoware software. Specimen of Inconel 718 are prepared in the dimension 3 x15mm and then used for experiment. Chemical composition of work material is given in Table 1. ( a ) CNGA1248E TABLE 1.CHEMICAL COMPOSITION OF WORK MATERIAL C Mn Si Cr Ni Co Mo Nb Al Fe (b) CNGA12412E In this experiment SIALON ceramic having three different nose radii with rhomboid shaped inserts are used. They are specially designed for high temperature application material. Their geometry is shown in Table 2.Tool holder PCLNL2525M12 ISO with p clamping is used having is rake angle 5 clearance angle -6 and approach angle 95. TABLE 2.GEOMETRY AND MATERIAL OF THE CUTTING TOOL INSERTS Material Nose radius Grade ISO Designation SIALON CERAMIC.8mm KYS25 CVD CNGA1248E ( c) CNGA12416E Fig1. Cutting tools used for experiment SIALON CERAMIC SIALON CERAMIC 1.2mm KYS25CVD CNGA12412E 1.6mm KYS3 CNGA12416E III.RESULTS AND DISCUSSION The cutting force generated during machining are recorded and is shown in Table 3.The one factor at a time approach of experimentation was employed to understand the mechanics of cutting force generation in response to input process parameter Volume I Issue VII IJRSI ISSN

3 International Conference on Multidisciplinary Research & Practice P a g e 19 Table 3. Observed values of cutting force components Exp No Input parameters, Cutting forces in Newton F c F t F f F c F t F f F c F t F f Vc mmin f mmrev -1 a p mm r h =.8mm r h =1.2mm r h =1.6mm Volume I Issue VII IJRSI ISSN

4 Force N International Conference on Multidisciplinary Research & Practice P a g e Effect of cutting speed on force magnitude Fig. 2(a-c) presents the variation of cutting force (F x, F y, F z ) magnitude with the change in cutting speed during high speed turning. The feed rate and depth of cut were fixed at.25mmrev -1 and.75mm respectively. It is seen from the plot that as the cutting speed increases from 1 to 4mmin -1, the magnitude of all force components reduces except for 1.6mm nose radius tool. This might happen that as the cutting speed increases, the temperature in the shear zone rise leading to thermal softening of the work material. As a result, the lower forces are required to shear the material in deformation zone. However in case of higher nose radii tool (1.6mm), because of larger area of contact in case of higher nose radius tool, the deformation is severe leading to sever high the frictional conditional leading to increase in the strain and strain rate and therefore the forces increased when cutting speed changes from to 4mmin FX=Cutting FY=radial FY=feed Speed V=(1-45)mmin -1, r h =.8mm. (a) FX=cutting FY=radial FZ=feed Speed V=(1 to 45) m/min1,r h =1.2mm FX=cutting FY=radial FY=feed (c) Fig. 2(a-c) Force components in dry machining of Inconel 718 with ceramic tool with f=.25 mmrev -1 and d=.75mm. 3.2 Effect of feed rate on force magnitude Fig.3. (a-c) presents the variation of cutting force (F x,f y,f z ) magnitude with the feed rate during high speed turning. The cutting speed and depth of cut were fixed at 25 mmin-1 and.75mmrespectively. It is seen from plots that as the feed rate increases from.15 to.4mmrev -1, the magnitude of all the force components increased. This is because the increase in co efficient of friction at tool tip nose radius is more. Hence grater forces needed to shear the material. In between feed rate.5 to.15 mmrev -1, the performance of all the inserts are good. However, at 1.6mm nose radius insert larger forces are produced as compared to.8 mm and 1.2mm nose radius. This is because grater friction experienced by the tool nose radius to shear the work piece material Speed V=1-4 mmin -1,r h =1.6mm Feed=(.5 to.4)mmrev -1,r h =.8mm (b) (a) Volume I Issue VII IJRSI ISSN

5 International Conference on Multidisciplinary Research & Practice P a g e Feed=(.5 to.4)mmrev- 1,r h =1.2mm D..C=(.35 to 1.5)mm,r h =.8mm (b) (a) D..C=(.35 TO 1.5)mm,r h =1.2mm (b) (c) Fig.3. (a-c) Force components in dry machining of Inconel 718 at (.5-.4) mmrev -1 feed rate with ceramic cutting tools having v=25 mmin -1 and d=.75mm. 3.3 Effect of depth of cut on force magnitude Fig. 4 presents the variation of cutting force (F x, F y, F z ) magnitude with the change in depth of cut during high speed turning. The speed and feed rate were fixed at 25mmin -1 and.25mmrev -1 respectively.it is seen from the plots that as the depth of cut increases from.35 to 1.5 mm the main cutting force components increased. At the larger depth of cut material removal rate is high. Higher forces are needed to shear the work material. Further increasing the depth of cut from.35 mm to.5 mm, with the insert having 1.6mm nose radius shows better performance. This might happens due to large contact area of 1.6mm nose radius resulting into gradual and uniform deformation of work material and hence, less forces are needed to shear work piece material D=(.35 to 1.5)mm,r h =1.6mm (c) Fig.4. (a-c) Force components in dry machining of Inconel 718 at ( ) mm depth of cut having v=25mmmin -1 and f=.25mmrev -1. Volume I Issue VII IJRSI ISSN

6 International Conference on Multidisciplinary Research & Practice P a g e 112 IV. CONCLUSIONS This experimental work involves analysis of cutting forces in high speed turning operation on Inconel 718 using ceramic insert. The following conclusions are yielded The CNGA12416E shaped ceramic insert shows better performance as compared to CNGA1248E and CNGA12412E shaped ceramic inserts in the cutting speed range 1 to mmin -1 -,f=.25mmrev -1 and a p =.5mm. Increasing the cutting speed from 1 to 35 mmin -1, all force components are reduces.8 mm nose radius. The suitable range for the CNGA1248E insert for high speed machining is Vc= 35mmin -1, f=.25mm. Cutting speed Vc =4mmin -1, f=.25mm and a p =.75mm is suitable for CNGA12412E shaped insert for high speed machining. Increasing feed rate from (.5 to.2) mmrev -1, VC=25mmin- 1 and a p =.75mm is suitable for all type insert during high speed machining of Inconel 718. This is because all force components are minimum in this range. ACKNOWLEDGEMENT The authors acknowledge support of MHRD, government of India for providing grant for CNC machine and kistler dynamometer procurement through TEQIP scheme. REFERENCES [1]. E.O.Ezugwu, J.Bonney, An overview of the mach inability of aero engine alloys, Journal of Material processing Technology 134(33) [2]. A.Senthil Kumar, A.Raja, Machinability of hardened steel using alumina based ceramic cutting tools, International Journal of Refractory Metals and Hard Material 21(3) [3]. Giampaolo E.D.Errico, Advanced ceramic tools: an experimental assessment in turning test, Journal of material processing Technology 54(1995) [4]. N.Narutaki.Y.Yamane, High- speed Machining of Inconel 718 with ceramic Tools, Annals of The CIRP Vol.42/1/1993. [5]. E.O.Ezugwu. S.H.Tang, Surface abuse when machining cast iron (G- 17) and nickel-base super alloy (Inconel 718) with ceramic tools, Journal of Material processing Technology 55(1995) [6]. L.Li,N,He, High speed cutting of Inconel 718 with coated carbide and ceramic insert, [7]. R.T.Coelho, L.R.Silva, Some effect of cutting edge preparation and geometric modification when turning INCONEL 718 at high speed, Journal of material processing Technology 148(4) [8]. A.Altin.M.Nalbant, The effect of cutting speed on tool wear and tool life when machining Inconel 718 with ceramic tools, Material and design 28(7) [9]. E.O.Ezugwu.J.Bonney, Machining of nickel-base Inconel 718 alloy with ceramic tools under finishing conditions with various coolant supply pressures, Journal of Material processing Technology( ) [1]. Mummer Nalbant, Abdullah Altin, The effect cutting speed and tool geometry on mach inability properties of nickel-base Inconel 718 super alloys, Material and design 8(7) [11]. J.M.Zhou,V.Bushlya, An investigation of surface damage in high speed turning of Inconel 718 with use of whisker reinforced ceramic tools, Journal of Material processing Technology 212(212) Volume I Issue VII IJRSI ISSN