In recent years, the applications of finite element method (FEM) in metal cutting operations have proved to be effective in studying the cutting process and chip 

formation. In particular, the simulation results can be used for both researchers and machine tool makers to optimize the cutting process and designing new tools. Many researches were done on two-dimensional simulation of  cutting process because the three-dimensional versions of FEM software required more computational time. The present work aims to simulate three-dimensional orthogonal cutting operations using FEM software of Deform-3D. Orthogonal 

cutting finite element model simulations were conducted to study the effect of cutting speed on effective-stress, strain and temperature in turning process. AISI 1045 was used as work material and cutting tool was TNMA 332 (uncoated carbide tool, SCEA = 0; BR = -5; SR = -5 and radius angle 60o). The emphasis on the designed geometries are limited to the changes in the cutting speed between

100 m/min and 450 m/min. The machining parameters of feed rate and depth of cut were kept constant at 0.35 mm/rev and 0.3 mm respectively. The simulation results show that by increasing the cutting speed causes a decrease in cutting force and effective-strain. On the other hand, increasing in

cutting speed will increase effective -strain and temperature of the chip formed

Che, Hassan Che Harun

Hendri, Yanda

Jaharah, A. Ghani

English

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Seminar II - AMReG 08, 15 Disember 2008, Bangi, Malaysia      1  Machining Simulation of AISI 1045 and Carbide Tool Using FEM  Hendri. Y., Jaharah A.G., Che Hassan C.H.  Department of Mechanics and Materials Faculty of Engineering Universiti Kebangsaan Malaysia   ABSTRACT  In recent years, the applications of finite element method (FEM) in metal cutting operations have proved to be effective in studying the cutting process and chip formation. In particular, the simulation results can be used for both researchers and machine tool makers to optimize the cutting process and designing new tools. Many researches were done on two-dimensional simulation of cutting process because the three-dimensional versions of FEM software required more computational time. The present work aims to simulate three-dimensional orthogonal cutting operations using FEM software of Deform-3D. Orthogonal cutting finite element model simulations were conducted to study the effect of cutting speed on effective-stress, strain and temperature in turning process. AISI 1045 was used as work material and cutting tool was TNMA 332 (uncoated carbide tool, SCEA = 0; BR = -5; SR = -5 and radius angle 60o). The emphasis on the designed geometries are limited to the changes in the cutting speed between 100 m/min and 450 m/min. The machining parameters of feed rate and depth of cut were kept constant at 0.35 mm/rev and 0.3 mm respectively.  The simulation results show that by increasing the cutting speed causes a decrease in cutting force and effective-strain. On the other hand, increasing in cutting speed will increase effective -strain and temperature of the chip formed.     Key Words: finite element method, three-dimensional of orthogonal cutting, AISI 1045, carbide tool   INTRODUCTION  Finite Element Analysis (FEA) technique was the first introduced in 1960s and has been widely used to analyze in designing  tools and forming processes. Based on the success of FEM simulations for bulk forming processes, many researchers developed their own FEM codes to analyze metal cutting processes during the early 1980s up to now (Marusich, et all, 1995; Cerenitti et al, 1996 ;  Xie et all, 1998; Shet et all, 2000).  Cerenitti (1996) assumed a rigid sharp tool and elasto-plastic workpiece, and defined a node separation criterion based on the geometry of the element approaching the cutting edge. Cerenitti (1996) used an early version of a commercial implicit FEM code “DEFORM-2DTM”. This code uses four-node quadrilateral elements and is based on static Lagrangian formulation. Today, DEFORM-3D™ code is commonly used by researchers and industry in  2machining simulation (Columbus, 2007).   Applications of FEM models for machining can be divided into six groups: 1) tool edge design, 2) tool wear, 3) tool coating, 4) chip flow, 5) burr formation and 6) residual stress and surface integrity.  The direct experimental approach to study machining processes is expensive and time consuming. For solving this problem, the finite element methods are most frequently used. Modeling tool wear using FEM has advantages over conventional statistical approach because it requires less experimental effort and it provides useful information such as deformations, stresses, strain and temperature in chip and the work piece, as well as the cutting force, tool stress and temperature on the tool working under specific cutting parameter. (Mackerle, 1999)   METHODOLOGY  This paper presents the application of Deform-3D in simulation orthogonal cutting process of AISI 1045 and carbide tool at various cutting speeds while the other machining parameters of feed rate and depth of cut were kept constant. The commercial software Deform-3D for deformation analysis was used to simulate orthogonal metal cutting process. It is based on an updated Lagrangian formulation and employs an implicit integration scheme. Figure 1 shows Geometry and Schematic of orthogonal cutting condition model.   Figure 2 Geometry and Schematic of orthogonal cutting condition model  The workpiece material was an AISI 1045 carbon steel. AISI 1045 carbon steel had been selected as the workpiece material in this study because it was well characterized and had been the focus of many recent modelling studies.  Table. 1 show flow stress models for AISI-1045 carbon steel used in the simulation.   The tool is modeled as a rigid body, so there are no mechanical properties need to be assigned and only thermal properties are needed. The mechanical properties of AISI 1045 steel and carbide cutting tool are shown in Table 3. The tool was -  - 3defined to be a rigid body which considers thermal transfer for modeling the cutting temperature field.   Deform  software had been used to simulate the effect of cutting speed on the parameter of machining when turning  AISI 1045 using uncoated carbide cutting tool. The simulations were performed by changing the cutting speed while the feet rate and depth of cut were kept constant at 0.35 mm/rev and 0.3 mm respectively as shown in Table 2. The simulation results of cutting force, effective-stress, strain and chip temperature on the cutting were studied and analyzed. The operation is simulated using a nose angle 60o and without used  of coolant.   The three-dimensional finite element model was generated under a plane strain assumption because the width of cut was larger than the undeformed chip thickness in this orthogonal cutting arrangement. The flow stress behavior of the work material and the contact conditions, physical and thermomechanical properties of the workpiece and tool materials, and cutting conditions are predefined and input to the simulation model as listed in Table 3.   Table 1    Flow stress models for AISI-1045 carbon steel   Material Model Equation for flow stress σ models Material constants Variables  Oxley (1989)    σ = σ1εn σ1,n=f(Tmod) ε, έ, T  Maekawa et al. (1983)  M m m/NaT /strain path   B e   e-1000 1000 1000NaT Nέ έ έ d                       B,N = f(T)M,m,a ε, έ, T Zerilli and Amstrong  (1987) σ = C0 + C1 + exp (-C3T + C4T ln έ*) + C2 εn C0,C1, C2,C3, C4,n ε, έ, T Johnson and Cook (1983)  σ = (A + Bεn)(1+C ln έ*)(1-T*m) A,B,C,m,n ε, έ, T El-Magd et al. (2003) σ = f(σo, έ), σo = f (ε, έ, T) ∆ σsteel – CK45 = f(T, έ), σsteel = σ + σsteel – CK45 έ*,m,n ε, έ, T   TABLE  2 Input Parameters in the simulation process  Parameters          Cutting Speed (m/min) 100 150 200 250 300 350 400 450  Feed Rate      Kept constant at 0.35 mm/rev Depth of cut      Kept constant at 0.3 mm Nose Angle (oC)      Kept constant at 60 oC    4 Table 3 Cutting condition to the simulation models   Tool Geometry of TNMA 332 (WC as base material, uncoated carbide tool) Side Cutting Edge Angle (SCEA)  0         Back Rake Angle (deg) Side Rake Angle (deg) -5 -5         Nose Angle (oC) 0.6                   Tool properties (uncoated carbide; Poisson’s ratio, 0.22) Modulus Young (GPa) 500         Modulus of Elasticity (Gpa) 641         Poison Ratio 0.26                   Boundary Condition Initial Temperature (oC) Shear friction factor  Heat transfer coefficient at the  workpiece tool interface (N/s mm°C) 20 0,5 45          Work peace geometry          Depth of cut Width of cut (mm) Length of workpeace 0,3 3,4 10                   Workpiece properties (AISI 1045; Poisson’s ratio, 0.30) Modulus of elasticity [37] (GPa) 215    210 165 160            at temperature (°C ) 20 200 400 600      Thermal expansion [38] (·105 °C-1) 1.1 1.2 1.3 1.4 1.4 1.5 1.5         at temperature (°C ) 100 200 300 400 500 600 700   Heat capacity [39] (N/mm2 ° C) 3.7 3.8 4.3 5.1 8.8 8.3 7.5 6 5.64       at temperature (°C ) 25 125 325 525 725 825 875 925 975 Thermal conductivity [39] (W/m °C) 42 43 38 35 29 28 24 23 23       at temperature (°C ) 25 100 300 500 700 800 900 950 1000    Figure 2 (a) Initial mesh and tool indentation, (b) Chip formation at step 25,   -  - 5              (c) Chip formation at step 50, (d) Developed continues chip at step 100.                        Figure 3  Example of the simulation result for cutting speed at                                 200 m/min (for running in 300 step)  Displacement, shape and surface mesh of tool and workpiece at initial mesh in the beginning of the cutting operation until the developed chip formation at step 100 as illustrated in Figure 2 a , 2b, 2c and 2d respectively The workpiece and the tool are characteristized by non uniform mesh distribution in the simulation. Very small element is required in the contact area between tool and workpiece because of very large temperature gradient and stress that will develop in this region during the simulation. Figure 3 shows an example of simulation result for cutting speed 100 m/min that was found from 300 steps of simulation running and needs longer time simulation.   RESULT AND DISCUSSION  Detailed Study of FEM Simulation  Figure 4a shows the simulation result for displacement. The longer the chip generated caused higher mesh displacement found as at the end of chip formed. The biggest deformation was occurred on the primary deformation zone, followed by the secondary deformation zone. This also cause higher stress occurred in this section. This result is agreeable with Kalhori (2001) where the major deformation during cutting process were concentrated in two region close to the cutting tool edge, and the bigger deformation were occurred in the primary deformation zone, followed by secondary deformation zone, sliding region and sticking region as shown in Figure 4b.     6           (a). Displacement     (b). Effective stress                                                          Figure  4  The simulation result for (a) displacement, cutting speed,  (b).                                    Stress  and strain at 100 m/min (step 100)                            Stress and temperature can be analyzed in detail based on its contour, this will give the value of stress and temperature for each of lines or points in all region of workpiece and chip formed as shown in Figure 5 and Figure 6.    Figure 5 shows that on the primary deformation zone, higher deformation is experienced, which resulted in higher stress It can be seen the contour of stress where higher at line of H (1520 MPa) and G (1300 MPa).     Figure 5 The simulation result for stress contour at 100 m/min                              (Step 100)                   -  - 7              Figure 6   The simulation result for temperature contour  at 100 m/min                                 (Step 100)   In the sticking region, the work piece material adheres to the tool and shear occurs within the chip, the frictional force is high and consequently is generated.  Therefore, the highest temperature in the chip usually occurs in the sliding region.  Figure 6  shows contour of temperature generated in each region, and higher temperatures are around  at line of G (439oC) and H (509oC) on sliding region.      Figure 7 shows the cutting force that generated during the cutting simulation, the cutting force remained constant (fluctuation on horizontal direction) after step 20, the same phenomenon is also observed in the gradient temperature, it remained constant after Step 42. Bigger fluctuation are found in effective-strain, therefore more difficult to predict  the strain value compared to predict  the effective-stress as given in Figure 8.               Figure 7  The graph result of simulation for cutting force and temperature                    contour  for cutting speed 100 m/min (step 100)  8 Figure  8  The graph result of simulation for cutting effective-stress and strain for      cutting speed 100 m/min (step 100)   Effect of Increasing of Cutting Speed on Machining Result  The cutting force, effective stress, strains and chip temperature at various cutting speed were studied and analyzed as shown in Table 4. The maximum and minimum value of each cutting parameter for cutting force, effective-stress, effective-strain and generated chip temperature in this simulation were plotted in Figure 9, Figure 10, Figure 11 and Figure 12 respectively.    In Table 4,  the simulation for cutting speed were done for 100 m/s -  450 m/min.    Table 4   The cutting force, effective stress, strain and chip temperature at                 various cutting speed were studied and analyzed.                 No Cut. Speed (m/min) Depth of cut (mm) Feed (mm/ tooth) Min Force (N) Max Force (N) Av. Force (N) Min Eff. Stress  (MPa) Max. Eff Stress (MPa) Av. Eff. Stress (MPa) Av. Strain  (mm/mm)  Min Temp  (C ) Max Temp (C ) Av. Temp (C ) 1 100 0,3 0,35 281 337 309 1253 1740 1497 3.9 553 478 516 2 150 0,3 0,35 249 400 325 1260 1778 1519 4.7 644 675 660 3 200 0,3 0,35 255 344 300 1330 1590 1460 5.3 707 763 735 4 250 0,3 0,35 256 349 303 1270 1680 1475 4.2 723 777 750 5 300 0,3 0,35 256 308 282 1400 1430 1415 4.1 780 821 801 6 350 0,3 0,35 250 325 288 1290 1550 1420 4.2 731 870 801 7 400 0,3 0,35 249 336 293 1300 1630 1465 5.1 937 984 961 8 450 0,3 0,35 250 272 261 1350 1450 1400 6.8 821 849 835  -  - 9    Figure  9 Cutting speed vs cutting force    Figure 10  Cutting speed vs           maximum effective-stress     Figure  11  Cutting speed vs                  Figure 12  Cutting speed vs maximum                      chip temperature      maximum effective-strain   Figure 9 shows that by the increasing of the cutting speed, it will decrease the cutting force. This is agreeable with theory that by the increasing of cutting speed will soften the material, therefore this will make material easier to cut in higher cutting speed condition.    Figure 10 shows that by increasing the cutting speed also will reduce the effective-stress. This is also agreeable with theory and Cerenitty. Et all (1996) an other research.  The good result were get for the graph of temperature where the increasing of cutting speed will increase the generated temperature on chip as given in Figure 12. This is agree with Cerenitti. et all (1996) where the maximum temperature of chip are increasing with increasing cutting speed.  Based on theory, the graph of effective-strain should remain constant, but in this simulation, as given in Figure 11, the increasing cutting speed cause a sligh increase effective-strain, this was caused by difficulty in getting the average of effective-strain value, because there were high fluctuation in resulted graphs.      10CONCLUSION  The distribution of cutting force, effective stress and temperature obtained from simulations are in good agreement with the result given in literature. From simulation, there can be concluded that by increasing of the cutting speed in turning of AISI 1045 using Tungsten Carbide (CW) will decreasing of cutting force and effective stress. In the different case, increasing of cutting speed cause increasing of generated temperature on chip.      ACKNOWLEDGEMENT  The authors would like to Government of Malaysia and Universiti Kebangsaan Malaysia for their financial support under 03-01-01-SF1214 and UKM-GUP-BTT-07-25-025 Grants.  REFERENCE  Aurich. J.C (2006),  Finite Element Modelling of Segmented Chip Formation,  Annals of the CIRP, Volume 11, 2006 Cerenitti A.E, Fallbohmer B.P, W. Wu C.W.T, Altan B.T (1996), Application of 2D FEM to Chip Formation in Orthogonal Cutting,  Journal of materials Processing Technology, Elsevier Science,  Volume 59 Columbus, OH (2007), DeformTM - 3D Machining (Turning) Lab, Scientific Forming Technologies Corporation.  Cerenitti.A.E,, Lazzaroni.C,  Menegardo. L,  Altan. T (2000), Turning SimulationUsing a Three- Dimensional FEM Code,  Journal of materials Processing Technology, Elsevier Science,  Volume 98, 2000 Jawahir. I. S (2008), An Intermediatary Level Short Course on Machining Process Modelling and Optimization for Improved Productivity, Machining Research Laboratory Center for Manufacturing, and department of Mechanical Engineering Lexington, USA  Kalhori. V. 2001, Modelling and Simulation of Mechanical Cutting,  Doctoral Thesis,  Institutionen for Maskinteknik  Mackerle. J (1999), Finite Element Analysis and Simulation of Machining: a Bibliography (1976 – 1996), Journal of Materials Processing Technology, Elsevier Science, Volume 86 Marusich, T.D. and Ortiz, (1995)., Modeling and Simulation of High-Speed  Machining, International Journal Num. Metallurgy Engineering, Volume  38. Shet, C. (2000), Finite Element Analysis of the Orthogonal  Metal Cutting  Process,  Journal of Materials Processing Technology, Elsevier Science,  Volume 105 Oxley, P. L. B. (1989). Mechanics of Machining: An Analytical Approach to  Assessing Machinability, 1989, pp. 223–227 (Ellis Horwood, Chichester, West Sussex). -  - 11Xie. J. Q, Bayoumi. A.E., Zbib. H. M. (1998),  FEA Modelling and Simulation of Shear Localized Chip Formation in Metal Cutting, Journal of Materials Processing Technology, Elsevier Science, Volume 30.                                              12                                                                  Email kepada amregfkej@gmail.com                                                                                                                                                           BORANG PENDAFTARAN   Nama         :        Tajuk        :      Penyelia     :   No Telefon :            (Pejabat)         (H/P)   E-Mail        :                 Hendri Yanda  Modelling of Cutting and Machining:     Turning of  Ductile Cast Iron using a three-    Dimensional FEM Method      Prof. Dr. Jaharah. A. Ghani   0162365017  Hendriynd@yahoo.com Persidangan AMReG ii 2008 -  - 13       14   -  - 15                                  

Machining Simulation of AISI 1045 and Carbide Tool Using FEM

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Machining Simulation of AISI 1045 and Carbide Tool Using FEM

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