This study is focused on numerical modeling analysis of laser-assisted micro-milling (LAMM) of difficult-to-machine alloys, such as Ti6Al4V, Inconel 718, and stainless steel AISI 422. Multiple LAMM tests are performed on these materials in side cutting of bulk and fin workpiece configurations with 100-300 µm diameter micro endmills. A 3D transient finite volume prismatic thermal model is used to quantitatively analyze the material temperature increase in the machined chamfer due to laser-assist during the LAMM process. Novel 2D finite element (FE) models are developed in ABAQUS to simulate the continuous chip formation with varying chip thickness with the strain gradient constitutive material models developed for the size effect in micro-milling. The steady-state workpiece and tool cutting temperatures after multiple milling cycles are analyzed with a heat transfer model based on the chip formation analysis and the prismatic thermal model predictions. An empirical tool wear model is implemented in the finite element analysis to predict tool wear in the LAMM side cutting process. The FE model results are discussed in chip formation, flow stresses, temperatures and velocity fields to great details, which relate to the surface integrity analysis and built-up edge (BUE) formation in micro-milling.
To analyze the surface defects caused by the size effect in micromachining using conventional micro tools, I have developed a novel finite element model with a strain gradient plasticity analysis to simulate the continuous chip formation for a complete micromilling cycle using Abaqus Explicit. My model was able to predict the steady-state tool and workpiece cutting temperatures in micromilling and laser-assisted micro milling. It was shown to be a useful tool in predicting size effect, tool wear, and surface integrity issues in micromachining.
Fig. 1 Micro Slotting and Side Cutting
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