A Numerical-Experimental Study on Orthogonal Cutting of AISI 1045 Steel and Ti6Al4V Alloy: SPH and FEM Modeling with Newly Identified Friction Coefficients

Mohamadreza Afrasiabi,Ivan Iovkov,Matthias Röthlin,Jannis Saelzer,Hagen Klippel,Andreas Zabel,Dirk Biermann,Konrad Wegener,Sebastian Berger

doi:10.3390/met11111683

Abstract

Numerical simulation of metal cutting with rigorous experimental validation is a profitable approach that facilitates process optimization and better productivity. In this work, we apply the Smoothed Particle Hydrodynamics (SPH) and Finite Element Method (FEM) to simulate the chip formation process within a thermo-mechanically coupled framework. A series of cutting experiments on two widely-used workpiece materials, i.e., AISI 1045 steel and Ti6Al4V titanium alloy, is conducted for validation purposes. Furthermore, we present a novel technique to measure the rake face temperature without manipulating the chip flow within the experimental framework, which offers a new quality of the experimental validation of thermal loads in orthogonal metal cutting. All material parameters and friction coefficients are identified in-situ, proposing new values for temperature-dependent and velocity-dependent friction coefficients of AISI 1045 and Ti6Al4V under the cutting conditions. Simulation results show that the choice of friction coefficient has a higher impact on SPH forces than FEM. Average errors of force prediction for SPH and FEM were in the range of 33% and 23%, respectively. Except for the rake face temperature of Ti6Al4V, both SPH and FEM provide accurate predictions of thermal loads with 5–20% error.

Highlights

As one of the most prevalent manufacturing operations with an enormous economic impact, metal cutting has always been in the research spotlight
As a first validation of the numerical results, process forces predicted by the Finite Element Method (FEM) and Smoothed Particle Hydrodynamics (SPH) simulations need to be compared against the experimental data
Three different friction coefficients are alternatively used in each SPH and FEM model: (1) constant μ; (2) temperature-dependent μ(T); and (3) velocity-dependent μ(v)

Summary

Introduction

As one of the most prevalent manufacturing operations with an enormous economic impact, metal cutting has always been in the research spotlight. The complex interplay between thermal and mechanical effects in metal cutting poses multiple challenges to its experimental and numerical investigation. Machining of titanium alloys like Ti6Al4V provides two major challenges: process-vibrations which are caused by the characteristic chip segmentation [1] and high temperatures on rake face and flank face resulting in extensive tool wear [2]. To achieve a further development of tools and processes to reduce the tool wear in machining, numerical models are important resources. The models are not yet qualified to achieve valid wear predictions over a broad parameter field. This applies to difficult-to-machine materials such as Ti6Al4V, and to less demanding materials such as AISI 1045 [5].

Methods

Results

Conclusion