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Chip formation simulations provide an effective tool for the further development of machining processes. The models on which the simulations are based require a realistic prediction of the flow stress behavior of the material as well as the friction behavior of tool and material. In the presented work, experimental investigations were carried out to characterize the flow stress and friction behavior for the machining of the cold work steel AISI D2 and the resulting models have been implemented in finite element chip formation simulations. These simulations are validated concerning mechanical loads using orthogonal cutting experiments. [ABSTRACT FROM AUTHOR]

The characteristic segmented chip formation of titanium alloy Ti6Al4V leads to a periodic excitation and therefore to vibrations during the process. One way to avoid these chip formation induced vibrations is to position a counter element, the constraint, in front of the primary shear zone which suppresses the segmentation mechanism. In this paper, the simulative design of the geometry and position of the constraint, which are decisive for the successful suppression of the segmented chip formation, is shown. The most promising design is then manufactured and used in experimental investigations and the results are compared with those from the simulations. [ABSTRACT FROM AUTHOR]

The productivity and the tool life of cutting tools are majorly influenced by the cutting edge micro shape. The identification of optimized cutting edges is usually based on empirical knowledge or is carried out in iterative investigation steps. This paper presents an approach to predict optimal cutting edge micro shapes with the aid of finite-element-simulations of the chip formation. The approach is investigated for the machining of the nickel-base alloy Inconel 718. The cutting edges are prepared by pressurized air wet abrasive jet machining. Utilizing this method, the prepared cutting edges have a certain profile, which is considered for the modelling. By applying a model for tool wear the influence of the cutting edge micro shape on the tool life span is estimated. Subsequently, a statistical modelling provides the prediction of the tool wear rate for any possible parameter set within the investigated range. This is used to find an optimized cutting edge profile that minimizes the tool wear. An experimental investigation concludes the optimization procedure. [ABSTRACT FROM AUTHOR]

Tool wear is an important criterion in metal cutting affecting part quality, chip formation and the economics of the cutting process. In order to account for tool wear adequately in tool and process design, simulation tools predicting tool wear in metal cutting processes are required. Within this paper, an advanced simulation approach is presented, coupling FE simulations of chip formation with a user-defined subroutine which extends the functionalities of the commercial FE code for wear simulation laying the focus on the development of this method. The continuous process of wearing is discretized in finite steps and the wear rate is modelled to be constant between. Based on the Usui wear rate equation, the local thermo-mechanical load obtained by FE simulation is transformed into local wear rates. The geometric representation of the wear progress is implemented via shifting of the finite element nodes of the engaged tool domain. A novel iterative procedure of updating the tool geometry in order to account for the wear progress is presented. [ABSTRACT FROM AUTHOR]

Steel strips are frequently used in the metal working industry for the manufacturing of tubes and bearing sleeves. These steel strips are produced by cold and warm rolling and are commonly coiled up for transportation purposes. Moreover, the obtained coils are split into customized sizes. In order to use the steel strips for further processing the edges need to be machined with respect to deburring and joint preparation. Therefore, specialized machine tools are used which apply common turning inserts with a translational cutting motion. On the one hand this process is high efficient but on the other hand the process reliability is affected by the formation of long continuous chips. In order to meet the requirements for an increased process reliability investigations on chip flow control are carried out with the aid of the finite element method (FEM). The acquired results are presented in this article. [ABSTRACT FROM AUTHOR]

The heat treatment has a major impact on the mechanical properties of steel alloys and therefore on the condition of a machining processes. In this paper, the low alloy steel 51CrV4 with different heat treatments is investigated in terms of its mechanical properties under high dynamic conditions using a Split Hopkinson Pressure Bar (SHPB) and by means of orthogonal cutting tests. The latter provide a detailed insight in the ongoing processes during chip formation by analyzing the present microstructure of the generated chips. Furthermore, the obtained data from the SHPB tests is used as an input for material models applied for the simulation of chip formation with the Finite-Element-Method. The results reveal fundamental differences in the chip formation mechanisms between the differently heat treated workpiece materials. [ABSTRACT FROM AUTHOR]

The conventional development of a coating system for cutting tools includes a variety of test series with elaborate experimental parameter studies. In particular, experimental investigations of the cutting behavior cause a significant consumption of cost, time and resources. In order to adapt the coating properties to the specific requirements of the cutting process, it is desirable to reduce the experimental effort of coating development by simulation of the machining process. Therefore, the main factors of the thermo-mechanical coating load in machining AISI 4140 were identified by means of 2D FEM chip formation simulations. In order to provide the required thermal and mechanical coating properties for the simulations, CrAlN-based coatings were deposited onto cutting inserts and extensively characterized. Within the simulations, the coating properties were varied between the physical and technological boundaries of CrAlN-based coatings. It was shown that the Young's modulus, the coating thickness and the friction coefficient significantly influence the thermomechanical load and the stress distribution within the coating. Finally, the cutting performance of the coated inserts was experimentally investigated and compared with the results of the simulations. Here, it was shown that delamination of the coating is particularly influenced by coating thickness. [ABSTRACT FROM AUTHOR]

Thermal effects often limit the performance of cutting processes. The energy spent in cutting is almost completely converted into heat which partly flows to workpiece, chip, and tool during the process. Therefore, knowledge about this partition is valuable for the process, tool, and coolant system design or for the compensation of thermal deformations of the workpiece and machine tool. For this reason, a simulation model based on the finite element method was developed to analyze the heat partition in dry metal cutting. The model utilizes the coupled Eulerian-Lagrangian method to simulate the chip formation in orthogonal cutting and to calculate the temperature distribution within workpiece, chip, and tool. This distribution was used to compute the heat partition between workpiece, chip, and tool in dependence of relevant process parameters. Furthermore, the results were validated by orthogonal cutting experiments and summarized in a formula to calculate the rate of heat flow into the workpiece as a function of those parameters. [ABSTRACT FROM AUTHOR]

In dry cutting an intensified heating of workpiece, tool and machine tool results in thermoelastic deformation which in turn causes dimensional and geometrical deviations of the machined parts. This paper presents a multiscale simulation method to calculate and compensate this effect. A chip formation model is used to compute the thermomechanical energy conversion and to determine the heat source of the cutting process on a mesoscopic model scale. This heat source is transferred on a macroscopic model that simulates the workpiece heating for a complete process sequence in order to analyze, reduce and compensate thermoelastic deformations. The multiscale simulation method is validated regarding the temperature and the resulting longitudinal workpiece deformation in dry turning of a gear shaft. However, the prediction of thermal deformation in radial dimensions needs additional validation with improved experiments and model features in future works. [ABSTRACT FROM AUTHOR]

In this paper FE-based tool wear simulation has been applied to complex shaped and coated cutting tools in turning operations. The coating has been considered by an own functional layer with specific friction and thermal properties as well as wear resistance. Therefore, a modified Usui tool wear model is calibrated for the coating and the substrate and combined in a three-dimensional simulation in order to simulate the wearing process including the baring of the substrate with a change in local thermal, friction and wear properties. Turning of AISI 1045 with PVD-TiAlN-coated and uncoated carbide tools was considered. The simulation results are validated by a comparison of simulated wear and external longitudinal turning experiments for a wide field of cutting parameters. [ABSTRACT FROM AUTHOR]