Modeling of minimum uncut chip thickness in micro machining of aluminum

State-of-the-art of surface integrity induced by tool wear effects in machining process of titanium and nickel alloys: A review

In this work, an attempt is made to reduce the detrimental effects that occurred during machining of Ti–6Al–4V by employing surface textures on the rake faces of the cutting tools. Numerical simulation of machining of Ti–6Al–4V alloy with surface textured tools was employed, taking the work piece as elasto-plastic material and the tool as rigid body. Deform 3D software with updated Lagrangian formulation was used for numerical simulation of machining process. Coupled thermo-mechanical analysis was carried out using Johnson-cook material model to predict the temperature distribution, machining forces, tool wear and chip morphology during machining. Turning experiments on Ti–6Al–4V alloy were carried out using surface textured tungsten carbide tools with micro-scaled grooves in preferred orientation such as, parallel, perpendicular and cross pattern to that of chip flow. A mixture of molybdenum disulfide with SAE 40 oil (80:20) was used as semi-solid lubricant during machining process. Temperature distribution at tool–chip interface was measured using an infrared thermal imager camera. Feed, thrust and cutting forces were measured by a three component-dynamometer. Tool wear and chip morphology were captured and analyzed using optical microscopic images. Experimental results such as cutting temperature, machining forces and chip morphology were used for validating numerical simulation results. Cutting tools with surface textures produced in a direction perpendicular to that of chip flow exhibit a larger reduction in cutting force, temperature generation and reduced tool wear.

Effect of micro-textured tools on machining of Ti–6Al–4V alloy: An experimental and numerical approach

This study focuses on the prediction of cutting forces during micro end milling using a novel approach that takes into account the chip thickness accumulation phenomenon. The proposed original force model considers the micro end milling kinematics, geometric errors of the machine tool–toolholder–mill system, elastic and plastic deformations of workpiece correlated with the minimum uncut chip thickness, and flexibility of the slender micro end mill. It also includes a novel analytical approach for the instantaneous area of cut. The chip thickness accumulation phenomenon can be manifested as chip thickness variations in the current tool rotation, resulting from material burnishing and elastic recovery in all previous tool rotations. The predicted forces consider the minimum uncut chip thickness value, which has been estimated directly from the micromilling process of AISI 1045 steel based on an original analytic–experimental approach that applies the identification of a stagnant point in the milling process. The results obtained show that the instantaneous and average micromilling forces determined using the proposed model have considerably better conformity with the experimental forces than those predicted using the commonly used rigid micro end milling model. Moreover, the non-linearity of the cutting forces as a function of feed per tooth is strongly affected by multiple cutting mechanism transitions observed during micromilling with uncut chip thicknesses close to the minimum uncut chip thickness value.

Prediction of cutting forces during micro end milling considering chip thickness accumulation

On the importance of the choice of the parameters of the Johnson-Cook constitutive model and their influence on the results of a Ti6Al4V orthogonal cutting model

Numerical modeling of metal cutting is a complex problem involving many nonlinear and coupled phenomena (high speed, large strains, large strain-rates, heat generation, etc.). Due to the large deformations, the mesh of the workpiece is often highly distorted. When it does not ends prematurely the computing, it slows it down and decreases the confidence in the results. Many formalisms are encountered in the literature to model the orthogonal cutting process, each with their pros and cons, more or less significant. This paper introduces the Coupled Eulerian-Lagrangian (CEL) formulation, in which the workpiece is described by the Eulerian formulation and the tool by the Lagrangian one. The comparison with experimental results and an Arbitrary Lagrangian-Eulerian (ALE) model with pure Lagrangian boundaries shows that the chip morphology and the cutting forces are well predicted by that new model. The absence of mesh deformation in the part does not decrease the stable time increment and therefore does not slow down the computing, which is competitive compared to the reference ALE model. This also increases confidence in the results given by the CEL model and opens new possibilities in the modeling of metal cutting.

Application of the Coupled Eulerian-Lagrangian (CEL) method to the modeling of orthogonal cutting

Numerical contribution to the comprehension of saw-toothed Ti6Al4V chip formation in orthogonal cutting

On the introduction of adaptive mass scaling in a finite element model of Ti6Al4V orthogonal cutting

Material constitutive model and chip separation criterion influence on the modeling of Ti6Al4V machining with experimental validation in strictly orthogonal cutting condition

Enrico Filippi

Papers

On the importance of the choice of the parameters of the Johnson-Cook constitutive model and their influence on the results of a Ti6Al4V orthogonal cutting model

Application of the Coupled Eulerian-Lagrangian (CEL) method to the modeling of orthogonal cutting

Numerical contribution to the comprehension of saw-toothed Ti6Al4V chip formation in orthogonal cutting

On the introduction of adaptive mass scaling in a finite element model of Ti6Al4V orthogonal cutting

Material constitutive model and chip separation criterion influence on the modeling of Ti6Al4V machining with experimental validation in strictly orthogonal cutting condition