3D FEA Simulations in Machining

The Finite Element Method (FEM) is arguably one of the most valuable tools when studying manufacturing processes. Therefore, it is widely used for the development of models that are able to predict the behavior of a manufacturing process under a variety of conditions with acceptable accuracy. Especially as computational resources develop, so does the FEM, making it an integral part of modern studies. Even though FEM can nowadays be implemented in 3D, 2D modeling still holds an important role. In the present work, a comparison between the application of 2D and 3D FEMs in machining was made, with both the advantages and disadvantages in mind. Specifically, an effort was made to capture the effectiveness of each method when studying standard machining results such as the cutting forces and torque, the temperatures, the residual stresses, and the tool wear.

The present chapter introduces the fundamentals of Finite Element Method (FEM) applied in standard machining processes such as turning, drilling, and milling. The most broadly used models for material flow, friction, and material separation and evolution are presented. In addition, a short introduction is included to meshing, element types, contact interface, and boundary conditions. Finally, the most recent modifications and advances in the various models implemented in FEM are presented, as well as the state of the art, especially in three dimensions.

In this research, the cutting forces that are induced during AISI52100 turning and the geometrical characteristics of the generated chips are studied by means of combined 2D and 3D Finite Element (FE) analyses. A number of 2D simulation tests were performed according to a design of experiments in order to evaluate the accuracy of three friction models, as well as a flow stress model at a given range of cutting conditions. Upon the comparison of the numerical results with the equivalent experimental ones, in terms of the thrust and cutting force, the model with the best fit was selected and, consequently, the establishment of a 3D FE model was achieved based on the 2D concepts. The three force components, as well as the chip’s geometrical aspects, were studied and visualized.

Finite Element Method (FEM) in machining is a technique that is widely accepted by the research community in the past few years, because it offers increased accuracy, robust results, and simplified test repeatability. The 3D-FE modeling of 7075-T6 aluminium alloy drilling is being presented in this study, with the use of commercial Finite Element Analysis (FEA) software, namely DEFORM^TM. The drilling process was simulated according to typical cutting parameters such as cutting speed and feed. The approximation of the process was achieved by implementing the most critical aspects, including flow stress of the material, tool geometry, friction behavior, and proper meshing. Prior to the development of the Finite Element (FE) model, an identical set of drilling tests was conducted with a CNC machine. Moreover, the results (thrust force and cutting torque) were outputted via a dynamometric system. The yielded numerical and experimental results demonstrated an increased agreement, with the relative error varying at reasonable levels for both cutting force and torque.

Nowadays, three-dimensional Finite Element (FE) modeling is used more often for the investigation of the machining processes, due to the increased approximation it provides and the fact that a number of variables cannot be examined by other means. The present work introduces a 3D FE model of CK45 (AISI1045) steel face-milling. In specific, it proposes a model for full immersion face-milling with a head mill. Moreover, it focuses on the comparison of the simulated chip formation process with experimental results, as well as the investigation of the tool wear in terms of the generated temperatures. The results of this study exhibit good agreement results for the generated chip morphology and dimensions. In addition, it is pointed out that tool wear is directly connected to cutting-edge temperatures and chip flow.