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Investigations into hard turning process using wiper tool inserts
Available online at www.sciencedirect.com
ScienceDirect Materials Today: Proceedings 5 (2018) 12579–12587
www.materialstoday.com/proceedings
ICMMM - 2017
Investigations into hard turning process using wiper tool inserts Amardeep Kumara1, S.K.Pradhanb a b
M.E. Student, Mechanical Engineering Department, NITTTR Bhopal-462002, INDIA
Associate Professor, Mechanical Engineering Department, NITTTR Bhopal-462002, INDIA
Abstract Now a day, major objectives of industries are to increase productivity and quality of product at low cost with minimum energy consumption which in turn lead to economic and eco-friendly manufacturing. Hard turning with the tool having wiper geometry possess these advantages over conventional turning process followed by grinding process. Hard turning is a primary metal cutting process which is extensively used for reduction of the diameter of workpiece to specified dimension and generation of smooth surface finish on the workpiece material having hardness greater than 45 HRC without supplementing it with grinding. Wiper geometry technology which is used for hard turning operation is made by carefully developed series of radii which make up the cutting edge. In conventional insert, nose of the edge has only one radius while in wiper geometry, wiper cutting edge has large main radius complemented by a number of smaller radii. Materials used for hard machining are hardened alloy steel, tool steels, case hardened steels, Inconel, nitride irons, hastelloys, Hadfield steel, hard chrome coated steels and heat treated powder metallurgical parts etc. While the cutting tool material used for hard turning are coated carbide tool, tungsten carbide, ceramics, CBN, PCBN etc. Few researchers have identified that efficient turning of material having high hardness is achieved through proper selection of process parameter to minimise surface roughness and cutting forces and for this optimization of process parameter is required available conventional and non-conventional optimization processes. Process parameter for hard turning are cutting speed, feed rate, depth of cut, cutting angle, hardness of workpiece, diameter of workpiece, nose radius of tool etc. while output parameter are surface roughness, material removal rate, energy consumption etc. While other researchers have used numerical techniques like Finite Element method to perform various analysis like thermal, vibration, buckling, stress and modal analysis related to hard turning. It is felt that a comprehensive review is required to identify the challenges exist in hard turning using wiper geometry tool and measures needed to overcome them. This paper presents a study of such research contributions, mechanics of material removal, finite element analyses, associated challenges and possible remedies related to hard turning with wiper geometry tool so as to propose a guideline for fresh researchers and practising production engineers. © 2017 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of International Conference on Materials Manufacturing and Modelling (ICMMM - 2017).
Keywords: Hard turning, wiper geometry, finite element method, cutting tool, optimization. 1. Introduction Main objectives of today’s industries are to produce high quality product at low cost with minimum time consumption. Machining process which consist of turning, milling, grinding, drilling etc. play an important role to 1
* Corresponding author Tel.: +91-7562980031; E-mail address: [email protected]
2214-7853 © 2017 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of International Conference on Materials Manufacturing and Modelling (ICMMM - 2017).
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Amardeep Kumar and S.K.Pradhan / Materials Today: Proceedings 5 (2018) 12579–12587
meet these objectives. Hard turning operation is a type of turning operation in which material which have hardness greater than 45 HRC is machined. In this process of machining, a non-rotary cutting tool moves linearly while workpiece rotate about their axis. Thus locus of cutting tool with respect to workpiece is helix. Basically, it is the process of removal of material from outer periphery of the axisymmetric workpiece. Hard turning is used to reduce the diameter of workpiece to specified dimension and generation of smooth surface finish on the workpiece. Generally, cylindrical body is used for turning. Input process parameters in turning operation are cutting speed, depth of cut, feed rate, cutting angle and coolant while performance parameters are surface roughness, material removal rate, tool wear rate, energy consumption etc. material which is used for hard machining are hardened alloy steel, tool steels, case – hardened steels, Inconel, nitride irons, hastelloys, Hadfield steel, hard – chrome – coated steels and heat – treated powder metallurgical parts etc. Tool which is used for hard turning are coated carbide tool, tungsten carbide, ceramics, CBN, PCBN etc. To reduce high cutting temperature, coolant can be used. There are various types of coolant which includes oil, oilwater emulsions, pastes, gels, aerosols (mists), air and other gasses but coolant is generally avoided in hard turning process because ceramics, CBN and PCBN inserts can tolerate high cutting temperature which eliminates cost and difficulties associated with coolant. 1.2 Hard turning operation using tool with wiper geometry Wiper geometry technology which is used for hard turning operation is made by carefully developed series of radii which make up the cutting edge. In conventional insert, as shown in figure 1 (a), nose of the edge having only one radius while in wiper geometry, as shown in figure 1(b), wiper cutting edge has large main radius complemented a number of smaller radii.
Figure 1 (a) Conventional insert (b) wiper insert
In turning with single point conventional insert, surface finish can easily be calculated by following relationship
Ra = Where “Ra” is average surface roughness and r is nose radius. It means that surface roughness increases with increase in feed for a cutting tool of given nose radius but it has been changed through the effect of its carefully developed edge in addition to this wiper geometry have improved chip breaking capacity. It is also designed for good chip control at low feed rate and smooth chip breaking at high feed. Hard turning with wiper geometry tool gives very high surface finish and so, grinding operation is being replaced by this process. Effect of feed and nose radius on surface finish in conventional and wiper inserts, as shown in figure 2.
Amardeep Kumar and S.K.Pradhan /Materials Today: Proceedings 5 (2018) 12579–12587
12581
Figure 2. Effect of feed and nose radius on surface finish in conventional and wiper inserts.
1.2.1 Feature which make hard turning different from conventional turning process ● In hard machining, shear angle is very low which increases with increase in hardness of workpiece and it doesn’t depends upon rake angle while in case of conventional machining, shear angle is large. ● In the case of hard machining, Tangential component of cutting force is lower than radial component of cutting force. With increase in flank wear, difference between these two forces increases. ● In case of hard machining, Chip compression ratio is two. ● Power required for plastic deformation of layer is more in hard machining. ● Power required for generation of new surface is more in case of hard machining. ● Heat generation in hard machining is more than conventional machining. 1.2.2 Advantage of hard turning using tool with wiper inserts ● In comparison to conventional insert, the surface finish does not deteriorate even if the feed rate become double. ● Cutting efficiency is improved by machining at high feed rate. ● As compared to the conventional insert, surface finish of the workpiece get improve with increase in feed rate under same condition. ● When high feed is applied, time required to cut one component is decreased by increasing in feed and thus productivity is improved. ● When high feed rate is applied, chip becomes thicker which gets break easily. Thus, chip control is improved. ● By this process machining of complex contours part can be done easily. ● In this process, types of components can be changed quickly. ● Many operations can be calculated in one setup. ● Material removal rate is high. ● Coolant is not required. ● Very small tool inventory. ● Low investment in machine tool. ● High flexibility. ● Ability to cut complex geometry with single machine setup. ● High surface finish as grinding process. That’s why grinding operation is being replaced by this process. 1.2.3 Issues in hard turning process ● In this process, cost of tooling is higher than grinding. ● Ratio of Length to diameter (L/D) of workpiece should be small because long thin part induces chatter. So L/D ratio of workpiece should not be more than 4 for unsupported workpiece. ● For successful hard machining, machine must be rigid. ● A very thin layer of material formed during hard machining is called White layer. White layer is harder than inner material formed. Generally, white layer is formed during machining of bearing steel which create problem for bearing races and receive high contact stress causes bearing failure. ● Surface roughness increases with increase in tool wear.
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1.2.4 Detrimental effect of high cutting temperature on cutting tool and workpiece 1. 2. 3. 4. 5. 6.
Rapid tool wear which reduces tool life. Thermal flaking and fracturing of the cutting edge due to thermal shocks. Built up edge formation. Dimensional inaccuracy of workpiece due to thermal distortion. Surface damage by oxidation, rapid corrosion, burning etc. Residual stresses and micro cracks induced at the surface.
2. Existing research efforts In the literature survey, it is found that many researchers had studied hard turning operation using tool with wiper geometry and optimized process parameter using different types of cutting conditions which is depicted through Table 1. Table 1: Different machining condition studied in Literature Review.
Name of researchers
Year
Objective of research
Rocha et.al [1]
2016
Optimizatio n of process parameter
Input parameter Cutting Speed, Feed, Depth of cut
Out parameter Surface roughness,
Workpiece material
Tool used
Software/methodology used
AISI H13 steel
PCBN wiper tool
Robust multiple criteria was used for decision making based on entropic measure to obtain optimal final solution.
Tool life, Ratio of material removal rate to cutting force
Schaal et.al [2]
D’Addona et.al [3]
2016
2015
Comparison of ground and laser machined wiper geometry on carbide inserts for high performance finishing
Cutting Speed,
Cutting force
Feed, Depth of cut
Machined surface quality
Comparison of turning operation using conventional turning tool, wiper inserted geometry
Cutting speed
Surface roughness
Feed Depth of cut
Response surface methodology(RSM)
AISI 1035 Steel
OHNS steel
TCGW 110204 carbide inserts. with wiper geometry made by conventio nal process and LASER machining process Conventio nal insert (WNMG 06 04 08 MT, 06 04 12 MT)
Nose radius Wiper
Normal boundary intersection (NBI) method Mixture of design expert(MDE) 3D CAD model
Taguchi method Analysis of variance(ANOVA) Analysis of means(AOM
Amardeep Kumar and S.K.Pradhan /Materials Today: Proceedings 5 (2018) 12579–12587
M’Saoubia et.al[4]
Balestrassi et.al [5]
Gaitonde et.al [6]
Gaitonde et.al [7]
2011
2011
2010
2009
tool and grinding process on the basis of surface roughness
Inserts geometry
Analysis of surface integrity in hard turning using wiper inserts compared with conventional inserts. Optimizatio n of hardened steel using Multivariate Robust parameter design in hard turning operation
Feed,
Comparison of conventional inserts and wiper inserts in hard turning operation
Investigation of machinabilit y in hard turning operation
insert (WNMG 06 04 08WT, 06 04 12 WT) Surface roughness
AISI 52100
PCBN Wiper inserts
Finite element method.
Surface roughness
AISI 52100 hardened steel
Wiper mixed ceramic coatedWit h TiCN
Full Factorial Design (FFD)
Nose radius
Cutting speed
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Feed
Multivariate Robust Parameter Design (MRPD)
Depth of cut Mean Squire Error (MSE) Two factor Workpiece hardness, tool flank wear Cutting speed
Principle Component Analysis (PCA Tool wear
Feed
Surface roughness
Machining time
Specific cutting force
Cutting speed
Tool wear
Feed
Surface roughness
Machining time
Specific cutting force
High Chromium AISI D2 cold worked Steel
High Chromium AISI D2 Cold worked steel
Conventio nal ceramic insert CC650, Wiper ceramic insert CC650W G, Wiper ceramic insert GC6050 WH Conventio nal ceramic insert CC650 Wiper ceramic insert CC650W G Wiper ceramic insert
Artificial Neural Network (ANN) Response Surface Methodology (RSM) MATLAB
Analysis of Variance (ANOVA) Full factorial design(FFD) Response Surface methodology (RSM)
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Kurniawan et.al [8]
Su et.al [9]
Amardeep Kumar and S.K.Pradhan / Materials Today: Proceedings 5 (2018) 12579–12587
2007
2006
Analysis of effect of process parameter on Tool life, tool wear
Cutting speed
Surface roughness
Feed
Tool life
Constant depth of cut
Tool wear
Analysis of cutting force in hard turning operation
Cutting speed
Crater wear Radial force
AISI 420 martensitic steel
51CrV4
Feed force Feed depth of cut
Tangential fore
GC6050 WH Coated carbide wiper tool CNMG 120408 CBN With Wiper cutting edge
Mathematical model for predicting forces Finite Element Method
3. Optimization techniques used for Hard machining processes The process which is used to for making system, design or decision as effective as possible is termed as optimization. The word “optimization” was first coined in 1857. Various types of software or methodology used for optimization of hard machining are Artificial Neural Network (ANN), Genetic algorithm (GA),Analysis of variance (ANOVA), Taguchi, Analysis of mean (AOM), Response surface methodology (RSM), Mixture of design Expert (MDE), Normal boundary intersection (NBI) method. Taguchi method. MINITAB etc 4. Finite element Simulation used for Hard machining processes It is a numerical technique used to find approximate solution to boundary value problem of partial differential equations. In this method, a body is discretized into a number of subdivisions called finite element. Thus, this method is representation of a body by assemblage of finite elements. An approximate function (shape function or interpolating function) is assumed to express field variable within each element at specified point called node or nodal point. Finite element method consist of three stages. (1) Preprocessing, (2) solution, (3) post processing. In preprocessing, model is generated and physical properties is applied. After that meshing is done to discretize the model and boundary conditions are applied. In solution stage, program convert it into mathematical model and solve it to get primary quantities (displacement, stress, force). In Post processing, values of primary quantities are obtained and examined. Various types of analysis such as thermal analysis, vibration analysis, buckling analysis, static analysis etc. can be done using finite element method. “ANSYS” is used as commercial software for finite element analysis. Few researchers have performed simulation of conventional machining processes like turning, milling, drilling to predict residual stresses, cutting forces, vibration analysis etc. but no one has attempted Finite element simulation of Hard turning process with wiper tool geometry to predict performance parameters. 4.1 Steps in finite element analysis of Hard turning operations Finite element simulation is done in three phase. Phase 1. Pre-processing. Step 1- Defining the geometry of workpiece and tool. Step2- Applying material properties such as Young's modulus, density, ultimate tensile strength, ultimate compressive strength, bulk modulus, poisson’s ratio, thermal conductivity, convective heat transfer coefficient, heat capacity, coefficient of thermal expansion etc. Step 3 - Defining boundary condition. ● Setting in type of simulation. a) Lagrangian mode (non-stationary process), in which nodes of mesh elements are connected to material. b) Eulerian approach (stationary process) in which motion of continuum occurs through a fix mesh. c) Arbitrary Lagrangian Eulerian method (ALE) is combination of both Lagrangian and Eulerian approach. In this approach motion of mesh is independent of material.
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●
Setting in Simulation mode. Deformation mode, heat transfer mode, coupled thermo-mechanical simulation mode. ● Object boundary conditions. a) Boundary conditions for workpiece and tool (friction, movement, and heat transfer), b) Boundary condition for tool workpiece interface (friction, heat transfer), c) Environmental boundary condition (convection, radiation). ● Chip separation- chip separation based on nodal distance, chip separation based on a critical indicator. Step 4- Meshing to discretise the geometry into finite elements. ● Defining element type (1-D bar element, 2-D triangular or quadrangular element, 3-D tetrahedron, pyramid, and hexahedron), ● Defining element size or number of elements. Phase2- Software solution of simulation of cutting operation. Phase3- Post processing to evaluate the results. ● Process model - simulation of orthogonal/oblique cutting process, high speed cutting process. ● Evaluation of temperature, stress and strain distribution, material removal rate, chip thickness, etc. 4.2 Governing equation for cutting operation. Elastic-viscoplastic finite element formulation. During cutting of material, large plastic deformation takes place in workpiece and so, geometrical and material nonlinearity is considered in finite element formulation. In order to face with the geometrical and material nonlinarites and the contact conditions between the cutting tool and boundary nodes of the workpiece, the finite element simulation is conducted incrementally. On the basis of updated Lagrangian formulation, elastic-viscoplastic finite element formulation of workpiece for the elemental equilibrium equation can be written in matrix form as }={ } (1) [KB] + [KS] { [ ] [Eep] [ ] dV
[KB] =
(2)
Where, [KB] is stiffness matrix. [ ] is strain displacement matrix, [Eep] is the elastic-viscoplastic constitutive matrix, [Ks] is the initial stress stiffness matrix, { } s the vector of the variation of incremental displacements, and (δf) is the vector of unbalanced forces during the iterative process used to achieve equilibrium and is defined as {
}={ }–
[ ] { } dV
(3)
4.3 Governing equation for thermal analysis Governing equation for heat transfer analysis can be written as (
)+
(
)+
(
)+Q=0
Assumptions: ● Material is isotropic in nature. ● There is no internal heat generation. ● Heat transfer occurs in steady state. Formulation of problem for thermal analysis using finite element method. [C] { }+ ([Kk] + [Kc]) { } = { } + { } Where, [ ]=
{ } {N}T ρ C dV
(4)
(5) (6)
[Kk] =
[ ] [B] k dV
(7)
[KC] =
{ } {N} h dSc
(8)
{
}=
{ }
(9)
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Where, {T} = Temperature vector at node. {N}= Shape function vector C= Heat capacity of workpiece h = Convective heat transfer coefficient. SC = Convection boundary of the workpiece. [Fp] = Vector of heat generation due to plastic deformation. = Rate of work due to plastic deformation. {Ft} = rate of heat generation on the node of the workpiece due to frictional. Assuming ρ, c, h, and k as direction independent. 5. Available materials and wiper tool for Hard turning operation List of available tool with wiper inserts are tabulated in table 2. CBN 010, CBN 060K, CBN 160C, CBN 300, CBN 400, CBN 150, DNMG-432-W6 (carbide) etc Table 2. List of material used for hard turning and its application. Materials Alloy steel (9310)
Hardness (HRC) 60
Alloy steel (4320)
60
AISI 1050 carbon steel AISI 5120 SAE-52100
62 62 60-64
Application Used to manufacture gear, crankshaft, heavy duty gear shaft in truck and aircraft construction etc. Used to manufacture Forged gear, pinions, and other heavy duty machinery components. Used to manufacture Forged shaft and gear. Connecting rod, forged cam shaft, gear, gear shaft, bushing etc. Used to manufacture bearing.
6. Conclusion In the present work, hard turning with wiper geometry tool is studied and the efforts made by different researchers are reviewed. Hard turning is a primary metal cutting process which is used for reduction of the diameter of workpiece to specified dimension and generation of smooth surface finish on the workpiece material having hardness greater than 45 HRC without supplementing it with grinding. Wiper geometry technology which is used for hard turning operation is made by carefully developed series of radii which make up the cutting edge. Materials used for hard machining are hardened alloy steel, tool steels, case hardened steels, Inconel, nitride irons, hastelloys, Hadfield steel, hard chrome coated steels and heat treated powder metallurgical parts etc. While the cutting tool material used for hard turning are coated carbide tool, tungsten carbide, ceramics, CBN, PCBN etc. It is found that AISI H13 Steel, AISI 1060 Steel, OHNS steel, AISI 4340 steel, AISD2 cold worked steel, AISI 420 martensitic steel, AISI 52100 Bearing steel etc. have been used in the experimentation of hard turning by many researchers but Alloy steel AISI 9310, AISI 4320, AISI 1050 CARBON STEEL has not been used. Very few researchers have used CBN/PCBN as tool inserts. It is identified that efficient turning of material having high hardness is achieved through proper selection of process parameter to minimize surface roughness and cutting forces and for this optimization of process parameter is required using available conventional and non-conventional optimization processes. Process parameter for hard turning are cutting speed, feed rate, depth of cut, cutting angle, hardness of workpiece, diameter of workpiece, nose radius of tool etc. while output process parameter are surface roughness, material removal rate, energy consumption etc. Very few researchers have optimized more than one parameter. In most of the optimization related research efforts, analysis of variance (ANOVA), Analysis of mean (AOM), Taguchi method and Response Surface methodology have been used for optimization through MINITAB software. Very few researchers used Artificial Neural Network (ANN) and Genetic Algorithm for optimization of process parameters related to turning using wiper tool. It is found that many researchers had optimized surface roughness, material removal rate, energy consumption, tool wear, ratio of MRR to cutting force using wiper insert tool where cutting speed, feed and depth of cut have been used as process parameters. Performance comparison of conventional and wiper ceramic inserts in
Amardeep Kumar and S.K.Pradhan /Materials Today: Proceedings 5 (2018) 12579–12587
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hard turning through artificial neural network modelling has also been attempted. Few researchers have used numerical techniques like Finite Element method to perform various analysis like thermal, vibration, buckling, stress and modal analysis related to conventional turning only. No one has attempted Finite Element Analysis on the tool having Wiper Insert Geometry in Hard Turning process. This work presents a study of such research contributions, mechanics of material removal, finite element analyses, associated challenges and possible remedies related to hard turning with wiper geometry tool. It has been reviewed that grinding process is not required when machining is done by this process which eliminate cost and energy required for grinding operation and leads to economic and ecofriendly manufacturing. References [1]
[2] [3] [4] [5]
[6] [7] [8] [9]
Rocha Luiz Célio Souza, Anderson Paulo de Paiva, Paulo Rotela Junior, Pedro Paulo Balestrassi1, Paulo Henrique da Silva Campos; Robust multiple criteria decision making applied to optimization of AISI H13 hardened steel turning with PCBN wiper tool; Int J Adv Manuf Technol,DOI 10.1007/s00170-016-9250-8 Schaal Nikolas, Konrad Wegener; Comparison of ground and laser machined wiper geometry on carbide inserts for high performance finishing; Procedia CIRP 46 ( 2016 ) 623 – 626 D'Addona D.M, Sunil J Raykar; Analysis of surface roughness in hard turning using wiper insert geometry; Procedia CIRP 41 (2016) 841 – 846 M’Saoubi R, J.Guddat , P.Alm, D.Meyer; Hard turning of AISI 52100 using PCBN wiper geometry inserts and the resulting surface integrity; Procedia Engineering 19 (2011) 118 – 124 Balestrassi P.P, E.J Paiva, L.G.D Lopes, J.R Ferreira, P.H Campos, A.P Paiva; A multivariate robust parameter design approach for optimization of AISI 52100 hardened steel turning with wiper mixed ceramic tool; Int. Journal of Refractory Metals and Hard Materials 30 (2012) 152–163 Gaitonde V.N, S.R Karnik, Luis Figueira, J. Paulo Davim; Performance comparison of conventional and wiper ceramic inserts in hard turning through artificial neural network modelling; Int J Adv Manuf Technol (2011) 52:101–114 DOI 10.1007/s00170-010-2714-3 Gaitonde V.N, S.R Karnik, Luis Figueira, J. Paulo Davim; Machinability investigations in hard turning of AISI D2 cold work tool steel with conventional and wiper ceramic inserts; Int. Journal of Refractory Metals & Hard Materials 27 (2009) 754–763 Kurniawan D, M.Y Noordin, S Sharif; Hard turning of stainless steel using wiper coated carbide tool; Int. J. Precision Technology, Vol. 1, No. 1, 2007 Su Wu, HE Xinfeng, Hurbert Kratz; Forces in Hard Turning of 51CrV4 with Wiper Cutting Tool; Tsinghua Science And Technology, ISSN 1007-0214 02/18 pp501-506,Volume 11, Number 5, October 2006.
ScienceDirect Materials Today: Proceedings 5 (2018) 12579–12587
www.materialstoday.com/proceedings
ICMMM - 2017
Investigations into hard turning process using wiper tool inserts Amardeep Kumara1, S.K.Pradhanb a b
M.E. Student, Mechanical Engineering Department, NITTTR Bhopal-462002, INDIA
Associate Professor, Mechanical Engineering Department, NITTTR Bhopal-462002, INDIA
Abstract Now a day, major objectives of industries are to increase productivity and quality of product at low cost with minimum energy consumption which in turn lead to economic and eco-friendly manufacturing. Hard turning with the tool having wiper geometry possess these advantages over conventional turning process followed by grinding process. Hard turning is a primary metal cutting process which is extensively used for reduction of the diameter of workpiece to specified dimension and generation of smooth surface finish on the workpiece material having hardness greater than 45 HRC without supplementing it with grinding. Wiper geometry technology which is used for hard turning operation is made by carefully developed series of radii which make up the cutting edge. In conventional insert, nose of the edge has only one radius while in wiper geometry, wiper cutting edge has large main radius complemented by a number of smaller radii. Materials used for hard machining are hardened alloy steel, tool steels, case hardened steels, Inconel, nitride irons, hastelloys, Hadfield steel, hard chrome coated steels and heat treated powder metallurgical parts etc. While the cutting tool material used for hard turning are coated carbide tool, tungsten carbide, ceramics, CBN, PCBN etc. Few researchers have identified that efficient turning of material having high hardness is achieved through proper selection of process parameter to minimise surface roughness and cutting forces and for this optimization of process parameter is required available conventional and non-conventional optimization processes. Process parameter for hard turning are cutting speed, feed rate, depth of cut, cutting angle, hardness of workpiece, diameter of workpiece, nose radius of tool etc. while output parameter are surface roughness, material removal rate, energy consumption etc. While other researchers have used numerical techniques like Finite Element method to perform various analysis like thermal, vibration, buckling, stress and modal analysis related to hard turning. It is felt that a comprehensive review is required to identify the challenges exist in hard turning using wiper geometry tool and measures needed to overcome them. This paper presents a study of such research contributions, mechanics of material removal, finite element analyses, associated challenges and possible remedies related to hard turning with wiper geometry tool so as to propose a guideline for fresh researchers and practising production engineers. © 2017 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of International Conference on Materials Manufacturing and Modelling (ICMMM - 2017).
Keywords: Hard turning, wiper geometry, finite element method, cutting tool, optimization. 1. Introduction Main objectives of today’s industries are to produce high quality product at low cost with minimum time consumption. Machining process which consist of turning, milling, grinding, drilling etc. play an important role to 1
* Corresponding author Tel.: +91-7562980031; E-mail address: [email protected]
2214-7853 © 2017 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of International Conference on Materials Manufacturing and Modelling (ICMMM - 2017).
12580
Amardeep Kumar and S.K.Pradhan / Materials Today: Proceedings 5 (2018) 12579–12587
meet these objectives. Hard turning operation is a type of turning operation in which material which have hardness greater than 45 HRC is machined. In this process of machining, a non-rotary cutting tool moves linearly while workpiece rotate about their axis. Thus locus of cutting tool with respect to workpiece is helix. Basically, it is the process of removal of material from outer periphery of the axisymmetric workpiece. Hard turning is used to reduce the diameter of workpiece to specified dimension and generation of smooth surface finish on the workpiece. Generally, cylindrical body is used for turning. Input process parameters in turning operation are cutting speed, depth of cut, feed rate, cutting angle and coolant while performance parameters are surface roughness, material removal rate, tool wear rate, energy consumption etc. material which is used for hard machining are hardened alloy steel, tool steels, case – hardened steels, Inconel, nitride irons, hastelloys, Hadfield steel, hard – chrome – coated steels and heat – treated powder metallurgical parts etc. Tool which is used for hard turning are coated carbide tool, tungsten carbide, ceramics, CBN, PCBN etc. To reduce high cutting temperature, coolant can be used. There are various types of coolant which includes oil, oilwater emulsions, pastes, gels, aerosols (mists), air and other gasses but coolant is generally avoided in hard turning process because ceramics, CBN and PCBN inserts can tolerate high cutting temperature which eliminates cost and difficulties associated with coolant. 1.2 Hard turning operation using tool with wiper geometry Wiper geometry technology which is used for hard turning operation is made by carefully developed series of radii which make up the cutting edge. In conventional insert, as shown in figure 1 (a), nose of the edge having only one radius while in wiper geometry, as shown in figure 1(b), wiper cutting edge has large main radius complemented a number of smaller radii.
Figure 1 (a) Conventional insert (b) wiper insert
In turning with single point conventional insert, surface finish can easily be calculated by following relationship
Ra = Where “Ra” is average surface roughness and r is nose radius. It means that surface roughness increases with increase in feed for a cutting tool of given nose radius but it has been changed through the effect of its carefully developed edge in addition to this wiper geometry have improved chip breaking capacity. It is also designed for good chip control at low feed rate and smooth chip breaking at high feed. Hard turning with wiper geometry tool gives very high surface finish and so, grinding operation is being replaced by this process. Effect of feed and nose radius on surface finish in conventional and wiper inserts, as shown in figure 2.
Amardeep Kumar and S.K.Pradhan /Materials Today: Proceedings 5 (2018) 12579–12587
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Figure 2. Effect of feed and nose radius on surface finish in conventional and wiper inserts.
1.2.1 Feature which make hard turning different from conventional turning process ● In hard machining, shear angle is very low which increases with increase in hardness of workpiece and it doesn’t depends upon rake angle while in case of conventional machining, shear angle is large. ● In the case of hard machining, Tangential component of cutting force is lower than radial component of cutting force. With increase in flank wear, difference between these two forces increases. ● In case of hard machining, Chip compression ratio is two. ● Power required for plastic deformation of layer is more in hard machining. ● Power required for generation of new surface is more in case of hard machining. ● Heat generation in hard machining is more than conventional machining. 1.2.2 Advantage of hard turning using tool with wiper inserts ● In comparison to conventional insert, the surface finish does not deteriorate even if the feed rate become double. ● Cutting efficiency is improved by machining at high feed rate. ● As compared to the conventional insert, surface finish of the workpiece get improve with increase in feed rate under same condition. ● When high feed is applied, time required to cut one component is decreased by increasing in feed and thus productivity is improved. ● When high feed rate is applied, chip becomes thicker which gets break easily. Thus, chip control is improved. ● By this process machining of complex contours part can be done easily. ● In this process, types of components can be changed quickly. ● Many operations can be calculated in one setup. ● Material removal rate is high. ● Coolant is not required. ● Very small tool inventory. ● Low investment in machine tool. ● High flexibility. ● Ability to cut complex geometry with single machine setup. ● High surface finish as grinding process. That’s why grinding operation is being replaced by this process. 1.2.3 Issues in hard turning process ● In this process, cost of tooling is higher than grinding. ● Ratio of Length to diameter (L/D) of workpiece should be small because long thin part induces chatter. So L/D ratio of workpiece should not be more than 4 for unsupported workpiece. ● For successful hard machining, machine must be rigid. ● A very thin layer of material formed during hard machining is called White layer. White layer is harder than inner material formed. Generally, white layer is formed during machining of bearing steel which create problem for bearing races and receive high contact stress causes bearing failure. ● Surface roughness increases with increase in tool wear.
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1.2.4 Detrimental effect of high cutting temperature on cutting tool and workpiece 1. 2. 3. 4. 5. 6.
Rapid tool wear which reduces tool life. Thermal flaking and fracturing of the cutting edge due to thermal shocks. Built up edge formation. Dimensional inaccuracy of workpiece due to thermal distortion. Surface damage by oxidation, rapid corrosion, burning etc. Residual stresses and micro cracks induced at the surface.
2. Existing research efforts In the literature survey, it is found that many researchers had studied hard turning operation using tool with wiper geometry and optimized process parameter using different types of cutting conditions which is depicted through Table 1. Table 1: Different machining condition studied in Literature Review.
Name of researchers
Year
Objective of research
Rocha et.al [1]
2016
Optimizatio n of process parameter
Input parameter Cutting Speed, Feed, Depth of cut
Out parameter Surface roughness,
Workpiece material
Tool used
Software/methodology used
AISI H13 steel
PCBN wiper tool
Robust multiple criteria was used for decision making based on entropic measure to obtain optimal final solution.
Tool life, Ratio of material removal rate to cutting force
Schaal et.al [2]
D’Addona et.al [3]
2016
2015
Comparison of ground and laser machined wiper geometry on carbide inserts for high performance finishing
Cutting Speed,
Cutting force
Feed, Depth of cut
Machined surface quality
Comparison of turning operation using conventional turning tool, wiper inserted geometry
Cutting speed
Surface roughness
Feed Depth of cut
Response surface methodology(RSM)
AISI 1035 Steel
OHNS steel
TCGW 110204 carbide inserts. with wiper geometry made by conventio nal process and LASER machining process Conventio nal insert (WNMG 06 04 08 MT, 06 04 12 MT)
Nose radius Wiper
Normal boundary intersection (NBI) method Mixture of design expert(MDE) 3D CAD model
Taguchi method Analysis of variance(ANOVA) Analysis of means(AOM
Amardeep Kumar and S.K.Pradhan /Materials Today: Proceedings 5 (2018) 12579–12587
M’Saoubia et.al[4]
Balestrassi et.al [5]
Gaitonde et.al [6]
Gaitonde et.al [7]
2011
2011
2010
2009
tool and grinding process on the basis of surface roughness
Inserts geometry
Analysis of surface integrity in hard turning using wiper inserts compared with conventional inserts. Optimizatio n of hardened steel using Multivariate Robust parameter design in hard turning operation
Feed,
Comparison of conventional inserts and wiper inserts in hard turning operation
Investigation of machinabilit y in hard turning operation
insert (WNMG 06 04 08WT, 06 04 12 WT) Surface roughness
AISI 52100
PCBN Wiper inserts
Finite element method.
Surface roughness
AISI 52100 hardened steel
Wiper mixed ceramic coatedWit h TiCN
Full Factorial Design (FFD)
Nose radius
Cutting speed
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Feed
Multivariate Robust Parameter Design (MRPD)
Depth of cut Mean Squire Error (MSE) Two factor Workpiece hardness, tool flank wear Cutting speed
Principle Component Analysis (PCA Tool wear
Feed
Surface roughness
Machining time
Specific cutting force
Cutting speed
Tool wear
Feed
Surface roughness
Machining time
Specific cutting force
High Chromium AISI D2 cold worked Steel
High Chromium AISI D2 Cold worked steel
Conventio nal ceramic insert CC650, Wiper ceramic insert CC650W G, Wiper ceramic insert GC6050 WH Conventio nal ceramic insert CC650 Wiper ceramic insert CC650W G Wiper ceramic insert
Artificial Neural Network (ANN) Response Surface Methodology (RSM) MATLAB
Analysis of Variance (ANOVA) Full factorial design(FFD) Response Surface methodology (RSM)
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Kurniawan et.al [8]
Su et.al [9]
Amardeep Kumar and S.K.Pradhan / Materials Today: Proceedings 5 (2018) 12579–12587
2007
2006
Analysis of effect of process parameter on Tool life, tool wear
Cutting speed
Surface roughness
Feed
Tool life
Constant depth of cut
Tool wear
Analysis of cutting force in hard turning operation
Cutting speed
Crater wear Radial force
AISI 420 martensitic steel
51CrV4
Feed force Feed depth of cut
Tangential fore
GC6050 WH Coated carbide wiper tool CNMG 120408 CBN With Wiper cutting edge
Mathematical model for predicting forces Finite Element Method
3. Optimization techniques used for Hard machining processes The process which is used to for making system, design or decision as effective as possible is termed as optimization. The word “optimization” was first coined in 1857. Various types of software or methodology used for optimization of hard machining are Artificial Neural Network (ANN), Genetic algorithm (GA),Analysis of variance (ANOVA), Taguchi, Analysis of mean (AOM), Response surface methodology (RSM), Mixture of design Expert (MDE), Normal boundary intersection (NBI) method. Taguchi method. MINITAB etc 4. Finite element Simulation used for Hard machining processes It is a numerical technique used to find approximate solution to boundary value problem of partial differential equations. In this method, a body is discretized into a number of subdivisions called finite element. Thus, this method is representation of a body by assemblage of finite elements. An approximate function (shape function or interpolating function) is assumed to express field variable within each element at specified point called node or nodal point. Finite element method consist of three stages. (1) Preprocessing, (2) solution, (3) post processing. In preprocessing, model is generated and physical properties is applied. After that meshing is done to discretize the model and boundary conditions are applied. In solution stage, program convert it into mathematical model and solve it to get primary quantities (displacement, stress, force). In Post processing, values of primary quantities are obtained and examined. Various types of analysis such as thermal analysis, vibration analysis, buckling analysis, static analysis etc. can be done using finite element method. “ANSYS” is used as commercial software for finite element analysis. Few researchers have performed simulation of conventional machining processes like turning, milling, drilling to predict residual stresses, cutting forces, vibration analysis etc. but no one has attempted Finite element simulation of Hard turning process with wiper tool geometry to predict performance parameters. 4.1 Steps in finite element analysis of Hard turning operations Finite element simulation is done in three phase. Phase 1. Pre-processing. Step 1- Defining the geometry of workpiece and tool. Step2- Applying material properties such as Young's modulus, density, ultimate tensile strength, ultimate compressive strength, bulk modulus, poisson’s ratio, thermal conductivity, convective heat transfer coefficient, heat capacity, coefficient of thermal expansion etc. Step 3 - Defining boundary condition. ● Setting in type of simulation. a) Lagrangian mode (non-stationary process), in which nodes of mesh elements are connected to material. b) Eulerian approach (stationary process) in which motion of continuum occurs through a fix mesh. c) Arbitrary Lagrangian Eulerian method (ALE) is combination of both Lagrangian and Eulerian approach. In this approach motion of mesh is independent of material.
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●
Setting in Simulation mode. Deformation mode, heat transfer mode, coupled thermo-mechanical simulation mode. ● Object boundary conditions. a) Boundary conditions for workpiece and tool (friction, movement, and heat transfer), b) Boundary condition for tool workpiece interface (friction, heat transfer), c) Environmental boundary condition (convection, radiation). ● Chip separation- chip separation based on nodal distance, chip separation based on a critical indicator. Step 4- Meshing to discretise the geometry into finite elements. ● Defining element type (1-D bar element, 2-D triangular or quadrangular element, 3-D tetrahedron, pyramid, and hexahedron), ● Defining element size or number of elements. Phase2- Software solution of simulation of cutting operation. Phase3- Post processing to evaluate the results. ● Process model - simulation of orthogonal/oblique cutting process, high speed cutting process. ● Evaluation of temperature, stress and strain distribution, material removal rate, chip thickness, etc. 4.2 Governing equation for cutting operation. Elastic-viscoplastic finite element formulation. During cutting of material, large plastic deformation takes place in workpiece and so, geometrical and material nonlinearity is considered in finite element formulation. In order to face with the geometrical and material nonlinarites and the contact conditions between the cutting tool and boundary nodes of the workpiece, the finite element simulation is conducted incrementally. On the basis of updated Lagrangian formulation, elastic-viscoplastic finite element formulation of workpiece for the elemental equilibrium equation can be written in matrix form as }={ } (1) [KB] + [KS] { [ ] [Eep] [ ] dV
[KB] =
(2)
Where, [KB] is stiffness matrix. [ ] is strain displacement matrix, [Eep] is the elastic-viscoplastic constitutive matrix, [Ks] is the initial stress stiffness matrix, { } s the vector of the variation of incremental displacements, and (δf) is the vector of unbalanced forces during the iterative process used to achieve equilibrium and is defined as {
}={ }–
[ ] { } dV
(3)
4.3 Governing equation for thermal analysis Governing equation for heat transfer analysis can be written as (
)+
(
)+
(
)+Q=0
Assumptions: ● Material is isotropic in nature. ● There is no internal heat generation. ● Heat transfer occurs in steady state. Formulation of problem for thermal analysis using finite element method. [C] { }+ ([Kk] + [Kc]) { } = { } + { } Where, [ ]=
{ } {N}T ρ C dV
(4)
(5) (6)
[Kk] =
[ ] [B] k dV
(7)
[KC] =
{ } {N} h dSc
(8)
{
}=
{ }
(9)
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Where, {T} = Temperature vector at node. {N}= Shape function vector C= Heat capacity of workpiece h = Convective heat transfer coefficient. SC = Convection boundary of the workpiece. [Fp] = Vector of heat generation due to plastic deformation. = Rate of work due to plastic deformation. {Ft} = rate of heat generation on the node of the workpiece due to frictional. Assuming ρ, c, h, and k as direction independent. 5. Available materials and wiper tool for Hard turning operation List of available tool with wiper inserts are tabulated in table 2. CBN 010, CBN 060K, CBN 160C, CBN 300, CBN 400, CBN 150, DNMG-432-W6 (carbide) etc Table 2. List of material used for hard turning and its application. Materials Alloy steel (9310)
Hardness (HRC) 60
Alloy steel (4320)
60
AISI 1050 carbon steel AISI 5120 SAE-52100
62 62 60-64
Application Used to manufacture gear, crankshaft, heavy duty gear shaft in truck and aircraft construction etc. Used to manufacture Forged gear, pinions, and other heavy duty machinery components. Used to manufacture Forged shaft and gear. Connecting rod, forged cam shaft, gear, gear shaft, bushing etc. Used to manufacture bearing.
6. Conclusion In the present work, hard turning with wiper geometry tool is studied and the efforts made by different researchers are reviewed. Hard turning is a primary metal cutting process which is used for reduction of the diameter of workpiece to specified dimension and generation of smooth surface finish on the workpiece material having hardness greater than 45 HRC without supplementing it with grinding. Wiper geometry technology which is used for hard turning operation is made by carefully developed series of radii which make up the cutting edge. Materials used for hard machining are hardened alloy steel, tool steels, case hardened steels, Inconel, nitride irons, hastelloys, Hadfield steel, hard chrome coated steels and heat treated powder metallurgical parts etc. While the cutting tool material used for hard turning are coated carbide tool, tungsten carbide, ceramics, CBN, PCBN etc. It is found that AISI H13 Steel, AISI 1060 Steel, OHNS steel, AISI 4340 steel, AISD2 cold worked steel, AISI 420 martensitic steel, AISI 52100 Bearing steel etc. have been used in the experimentation of hard turning by many researchers but Alloy steel AISI 9310, AISI 4320, AISI 1050 CARBON STEEL has not been used. Very few researchers have used CBN/PCBN as tool inserts. It is identified that efficient turning of material having high hardness is achieved through proper selection of process parameter to minimize surface roughness and cutting forces and for this optimization of process parameter is required using available conventional and non-conventional optimization processes. Process parameter for hard turning are cutting speed, feed rate, depth of cut, cutting angle, hardness of workpiece, diameter of workpiece, nose radius of tool etc. while output process parameter are surface roughness, material removal rate, energy consumption etc. Very few researchers have optimized more than one parameter. In most of the optimization related research efforts, analysis of variance (ANOVA), Analysis of mean (AOM), Taguchi method and Response Surface methodology have been used for optimization through MINITAB software. Very few researchers used Artificial Neural Network (ANN) and Genetic Algorithm for optimization of process parameters related to turning using wiper tool. It is found that many researchers had optimized surface roughness, material removal rate, energy consumption, tool wear, ratio of MRR to cutting force using wiper insert tool where cutting speed, feed and depth of cut have been used as process parameters. Performance comparison of conventional and wiper ceramic inserts in
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hard turning through artificial neural network modelling has also been attempted. Few researchers have used numerical techniques like Finite Element method to perform various analysis like thermal, vibration, buckling, stress and modal analysis related to conventional turning only. No one has attempted Finite Element Analysis on the tool having Wiper Insert Geometry in Hard Turning process. This work presents a study of such research contributions, mechanics of material removal, finite element analyses, associated challenges and possible remedies related to hard turning with wiper geometry tool. It has been reviewed that grinding process is not required when machining is done by this process which eliminate cost and energy required for grinding operation and leads to economic and ecofriendly manufacturing. References [1]
[2] [3] [4] [5]
[6] [7] [8] [9]
Rocha Luiz Célio Souza, Anderson Paulo de Paiva, Paulo Rotela Junior, Pedro Paulo Balestrassi1, Paulo Henrique da Silva Campos; Robust multiple criteria decision making applied to optimization of AISI H13 hardened steel turning with PCBN wiper tool; Int J Adv Manuf Technol,DOI 10.1007/s00170-016-9250-8 Schaal Nikolas, Konrad Wegener; Comparison of ground and laser machined wiper geometry on carbide inserts for high performance finishing; Procedia CIRP 46 ( 2016 ) 623 – 626 D'Addona D.M, Sunil J Raykar; Analysis of surface roughness in hard turning using wiper insert geometry; Procedia CIRP 41 (2016) 841 – 846 M’Saoubi R, J.Guddat , P.Alm, D.Meyer; Hard turning of AISI 52100 using PCBN wiper geometry inserts and the resulting surface integrity; Procedia Engineering 19 (2011) 118 – 124 Balestrassi P.P, E.J Paiva, L.G.D Lopes, J.R Ferreira, P.H Campos, A.P Paiva; A multivariate robust parameter design approach for optimization of AISI 52100 hardened steel turning with wiper mixed ceramic tool; Int. Journal of Refractory Metals and Hard Materials 30 (2012) 152–163 Gaitonde V.N, S.R Karnik, Luis Figueira, J. Paulo Davim; Performance comparison of conventional and wiper ceramic inserts in hard turning through artificial neural network modelling; Int J Adv Manuf Technol (2011) 52:101–114 DOI 10.1007/s00170-010-2714-3 Gaitonde V.N, S.R Karnik, Luis Figueira, J. Paulo Davim; Machinability investigations in hard turning of AISI D2 cold work tool steel with conventional and wiper ceramic inserts; Int. Journal of Refractory Metals & Hard Materials 27 (2009) 754–763 Kurniawan D, M.Y Noordin, S Sharif; Hard turning of stainless steel using wiper coated carbide tool; Int. J. Precision Technology, Vol. 1, No. 1, 2007 Su Wu, HE Xinfeng, Hurbert Kratz; Forces in Hard Turning of 51CrV4 with Wiper Cutting Tool; Tsinghua Science And Technology, ISSN 1007-0214 02/18 pp501-506,Volume 11, Number 5, October 2006.