Tool wear and heat transfer analyses in dry machining based on multi-steps numerical modelling and experimental validation B. Haddag, M. Nouari n University of Lorraine, Laboratoire d’E ´ nerge´tique et de Me´canique The´orique et Applique ´e, LEMTA CNRS-UMR 7563, Mines Nancy, GIP-InSIC, 27 rue d’Hellieule, St-Die´-des-Vosges, France article info Article history: Received 31 August 2012 Received in revised form 10 January 2013 Accepted 13 January 2013 Keywords: Tool wear Heat transfer Interface temperature 3D FE Multi-steps modelling Dry machining abstract In machining, tool–chip interface parameters such as pressure, temperature, sliding velocity and friction are extremely difficult to estimate only by experimental means. Theoretical methods can then give important solutions for predicting these quantities required for the assessment of tool wear. This work deals with a multi-steps modelling strategy based on several numerical calculations. The first step is a 3D thermomechanical analysis of the chip formation process. Cutting forces, chip morphology and chip flow direction as well as tool–chip interface parameters are obtained. The second step concerns the tool wear prediction using tool–chip interface parameters. The last step focuses on a 3D thermal analysis of the heat diffusion into the cutting tool using adequate thermal loading. An applied non- uniform heat flux is estimated using contact parameters obtained from the first step. Obtained results at each step of calculation are compared to experimental data. The predicted tool wear has been found in good agreement with experiments, and measured temperatures (using embedded thermocouples) very close to the temperature obtained by the last step of numerical calculation. & 2013 Elsevier B.V. All rights reserved. 1. Introduction Metal cutting is characterised by extreme contact loading at the tool–chip interface. The coupling between the thermal and the mechanical loads leads to tool failure, especially under dry configuration, i.e. machining without using lubrication. Efficient heat transfer and temperature rise at the tool–chip interface play an important role in preserving the structural integrity of the cutting tool. Generally, interface parameters are extremely diffi- cult to estimate only by experimental means because of the high contact pressure, high temperature, and intense friction applied to the tool–chip interface during the machining process. Theore- tical methods can give important solutions for predicting tool wear. Analytical models are generally based on several assumptions (geometrical simplifications, boundary conditions, simplified tool–workpiece configuration, etc.) which allow a rapid estima- tion of some thermomechanical parameters. Such developments can be found in [1–9]. Some models are dedicated to tool wear estimation, as proposed e.g. by Usui et al. [10–12], Molinari and Nouari [13], and Luo et al. [14]. Besides, numerical models are more efficient for cutting operations where complex tool geometry and/or tool–workpiece configuration should be considered. Finite Element [15–24], Difference Element [25,26] and more recently Smoothed Particle Hydrodynamics [27] methods are an example of such approaches used in this case. In recent years, as much as 90 percent of the published work has used the Finite Element Method (FEM). In fact, the FEM allows treating the chip formation process with few assumptions, particularly when cutting process should be treated under the 3D configuration (non-orthogonal cutting conditions), as in the present work. However, compared to analytical approaches, the high computation time remains the critical point of numerical approaches. Cutting process is modelled considering either the tool– workpiece couple, as in [15–27], or only the cutting tool with adequate thermomechanical loading, as in [28–41]. For the first case, chip formation process is globally analysed, including in some research works tool wear estimation, as performed by Filice et al. [42], and Lorentzon and J¨ arvstrat [43] using 2D FE model- ling. However, in most research works, the problem is treated in orthogonal cutting configuration. The main quantities estimated are the cutting force, the chip morphology and tool–chip interface characteristics (contact length/area, contact pressure, interface temperaturey). Simulations with FEM in 3D case are performed recently thanks to advanced developments in remeshing techni- ques in several commercial FE codes, like Deform TM [44] and Abaqus TM [45]. But including tool wear prediction in 3D case remains a big challenge for scientific community. Since the integrity of cutting tools during machining is of particular Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/wear Wear 0043-1648/$ - see front matter & 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.wear.2013.01.028 n Corresponding author. Tel.: þ33 3 29 42 22 26; fax: þ33 3 29 42 18 25. E-mail addresses: badis.haddag@univ-lorraine.fr (B. Haddag), mohammed.nouari@univ-lorraine.fr (M. Nouari). Please cite this article as: B. Haddag, M. Nouari, Tool wear and heat transfer analyses in dry machining based on multi-steps numerical modelling and experimental validation, Wear (2013), http://dx.doi.org/10.1016/j.wear.2013.01.028i Wear ] (]]]]) ]]]–]]]