Mathias Agmell

A fully coupled thermomechanical two-dimensional simulation model for orthogonal cutting: formulation and simulation

In this paper a fully coupled thermomechanical two-dimensional simulation model for orthogonal cutting is presented. The model is based on the arbitrary Lagrangian–Eulerian formulation with the remeshing technique. The material model used for the workpiece material includes Johnson–Cook plasticity, and as the chip separation criterion the Johnson–Cook damage law is employed. The different friction zones are modelled by the Coulomb friction law with a maximum limit for the friction. The capability of the model to represent the cutting process realistically is validated by performing simulations for different feed depths. The model is validated by comparison of the simulated values and measured experimental data for several different important process parameters, such as the feed force, the cutting force, the chip thickness ratio, the relative deformation widths, and the temperature distribution. The results from the simulations showed very good agreement with the experimental data.

A Numerical and Experimental Investigation of the Deformation Zones and the Corresponding Cutting Forces in Orthogonal Cutting

This study are focused on the deformation zones occurring in the work piece in a machining process and the corresponding cutting forces. The fully coupled thermo-mechanical FE-model for orthogonal cutting, developed in [1] is utilized. The work piece material is modeled with Johnson-Cook plasticity including damage formulation. Simulations for different feed depths were performed. The cutting forces, the chip thickness ratio and the deformation widths were determined experimentally by the quick-stop images and a force measurements. The results from the simulations have been compared to experimental data for the cutting forces and the chip thickness ratio as a function of the theoretical chip thickness.

Modeling subsurface deformation induced by machining of Inconel 718

ABSTRACT Traditionally, the development and optimization of the machining process with regards to the subsurface deformation are done through experimental method which is often expensive and time consuming. This article presents the development of a finite element model based on an updated Lagrangian formulation. The numerical model is able to predict the depth of subsurface deformation induced in the high- speed machining of Inconel 718 by use of a whisker-reinforced ceramic tool. The effect that the different cutting parameters and tool microgeometries has on subsurface deformation will be investigated both numerically and experimentally. This research article also addresses the temperature distribution in the workpiece and the connection it could have on the wear of the cutting tool. The correlation of the numerical and experimental investigations for the subsurface deformation has been measured by the use of the coefficient of determination, R2. This confirms that the finite element model developed here is able to simulate this type of machining process with sufficient accuracy.

Analysis of the minimum chip thickness during turning of duplex stainless steel

The goal of this study has been to establish a method for quantifying the minimum chip thickness, h1min, during longitudinal turning of duplex stainless steel, and explore how the value of h1min changes with varying process parameters. Based on experimental results, it was found that the tool edge radius only has a limited influence on the size of h1min up to a certain feed level after which the chip flow direction close to the nose radius will have an increasingly pronounced effect. Experimental results show that h1min may be as large as 40% of the theoretical chip thickness when machining duplex stainless steel, results which were corroborated by an finite element method (FEM) analysis. Thus, it can be concluded that a substantial amount of workpiece material will only be deformed onto the machined surface or will form the side flow and not removed as a chip.

Correlation between edge radius of the cBN cutting tool and surface quality in hard turning

AbstractcBN cutting tools with superior mechanical properties are widely used in machining various hard materials. The microgeometry of cBN cutting tools, such as the edge radius, has great influence on the surface quality of components and tool life. For optimized tool geometry, it is crucial to understand the influence of the cBN cutting tool microgeometry on the machined surface quality. In this study, the attempt has been made to investigate the correlation between the cutting tool edge radius and surface quality in terms of the surface roughness and subsurface deformation through a FE simulation and experiment. Machining tests under different machining conditions were also conducted and the surface roughness and subsurface deformation were measured. Surface roughness and subsurface deformation were produced by the cutting tools with different edge radii under various cutting parameters. Both results from the FE simulation and machining tests confirmed that there was a significant influence on the surface quality in terms of both the surface roughness and subsurface quality from the edge radius. There is a critical edge radius ofcBN tools in hard turning in terms of surface quality generated.