1. MODELLING THERMAL EFFECTS IN MACHINING BY FINITE ELEMENT METHODS Authors Andrea Bareggi (presenter) Andrew Torrance Garret O’Donnell IMC 2007 Department of Mechanical and Manufacturing Engineering The University of Dublin Trinity College Trinity College Dublin

2. Introduction FE modelling for metal cutting Stress, strain, strain rate predictions Temperature distribution in the primary, secondary and tertiary sub-cutting zones Trinity College Dublin IMC 2007 Cutting forces, plastic deformation (shear angles and chip thickness) Temperature in the workpiece, chip and tool

3. Commercial packages Trinity College Dublin IMC 2007 ABAQUS Manual design of geometry, meshing and boundary condition setting No material library, but materials can be defined in detail Partial support in adaptive remeshing Good control of the solver

4. Commercial packages Trinity College Dublin IMC 2007 ADVANTEDGE Very efficient interface to rapidly configure a model, tool library is provided Extensive material library Uses adaptive remeshing, but controls can not be modified Not suitable for customising control functions

5. IMC 2007 Commercial packages Trinity College Dublin DEFORM 3D Built in “wizard” for machining Good material library and comprehensive material editor Uses adaptive remeshing, good control of meshing parameters The user can chose the solver and minimal control is permitted

6. Problem formulation Trinity College Dublin IMC 2007 Incremental Lagrangian formulation Implicit integration method Solver with sparse matrix Direct method

7. Problem formulation Trinity College Dublin Cutting speed: 270m/min Feed: 0.06mm/rev Depth of cut: 0.5mm Effective rake angle = 0° nose radius = 0.2mm Cooling method: air jet AISI 1020 steel workpiece,1.5 mm of length, plastic WC insert with reduced heat capacity, rigid workpiece insert IMC 2007

8. Thermal boundary conditions Trinity College Dublin No cooling, natural convection, h=20 W/m ²/K Air jet, overhead position, h=2000 W/m ²/K Air jet, interface position, h=2000 W/m ²/K IMC 2007 overhead interface Interface nozzle dir. Overhead nozzle dir.

9. Results Trinity College Dublin IMC 2007 Steady state condition: workpiece, interface, insert Temperature prediction: workpiece, chip and interface Chip temperature (416°C)

10. Results Trinity College Dublin IMC 2007 feed=0.06mm/rev depth=0.5mm speed=270m/min Max workpiece temp. (°C) Interface temp. (°C) Chip temp. (°C) Cutting Force (N) Dry cutting 73771041693 Air jet cooling, overhead 72162738992 Air jet cooling, interface 72764840895 Reduction of interface temperature Best cooling in overhead position No influence on the cutting force

11. Results Trinity College Dublin IMC 2007 Prediction of gradient temperature within the insert Developing of experimental techniques for investigating temperature Temp (°C) A=20 B=88 C=156 D=225 E=293 F=361 G=429 H=498 I=566 J=634 K=702

12. Conclusion Trinity College Dublin IMC 2007 Results consistency: analytical results, ADVANTEDGE simulations, preliminary temperature measurements Finite Elements: cost saving in experimental work, process insight in cooling and lubricating method 3D modelling techniques under development, in particular with cooling

13. Further research Trinity College Dublin IMC 2007 Refinement of the model, estimation of the heat transfer coefficients, improved approach to jet modelling Simulation with different workpiece materials and cutting conditions Experimental validation, currently ongoing

14. Literature & Acknowledgements Trinity College Dublin IMC 2007 N.A. Abukhshim, P.T. Mativenga, M.A. Sheikh, Heat generation and temperature prediction in metal cutting: A review and implications for high speed machining, International Journal of Machine Tools & Manufacture 46 (2006) 782–800 J.D. Gardner, A.Vijayaraghavan, D.A. Dornfeld, Comparative Study of Finite Element Simulation Software, eScholarship Repository, University of California, Copyright c 2005 by the authors T. O’Donovan, Fluid flow and heat transfer of an impinging air jet, Phd. Thesis, Mechanical & Manufacturing Engineering, Trinity College Dublin, 2005 D. Umbrello, L. Filice, S. Rizzuti, F. Micari, On the evaluation of the global heat transfer coefficient in cutting, International Journal of Machine Tools & Manufacture 47 (2007) 1738–1743

15. Literature & Acknowledgements Trinity College Dublin IMC 2007 Acknowledgements Christian E. Fischer, Ph.D., PE, (Scientific Forming Technologies Corporation, Columbus, Ohio, USA) Questions?