The thermomechanical interaction of the tool with the chip in the most loaded secondary cutting zone depends on the contact length of the tool rake face with the chip. Experimental studies of the dependency of the contact length on the cutting speed, the undeformed chip thickness, and the tool rake angle, performed by the optical method, are used for comparison with the contact length obtained by the FE modeling of the orthogonal cutting process. To determine the parameters of the constitutive Johnson–Cook equation, which serves as a material model of the FE cutting model that has a predominant influence on the contact length, a software-implemented algorithm was developed. This algorithm is based on determining the generalized parameters of the constitutive equation through finding the intersection of these parameter sets. The plurality intersection of the parameter sets of the constitutive equation is determined by means of the design of experiments and refined by subsequent multiple iterations. The comparison of the contact length values, obtained by simulating the cutting process using the generalized parameters of the constitutive equation as a material model with their experimental values, does not exceed 12% for a wide range of cutting speeds and depths of cut, as well as for the tool rake angle.

Metalworking operations rely on the successful application of metalworking fluids (MWFs) for effective and efficient operation. Processes such as grinding or drilling often require the use of MWFs for cooling, lubrication, and chip removal. Electrochemical machining processes require electrolyte flow to operate. However, in those machining operations, a fundamental understanding of the mode of action of MWF is lacking due to the unknown flow dynamics and its interaction with the material removal during the process. Important information on the behaviour of MWFs during machining can be obtained from specific experimental flow visualisation studies. In this paper, promising flow visualisation analysis techniques applied to exemplary machining processes (grinding, sawing, drilling, and electrochemical machining) are presented and discussed. Shadowgraph imaging and flow measurements, e.g., particle image velocimetry, allow the identification of typical flow and MWF operating regimes in the different machining processes. Based on the identification of these regimes, efficient machining parameters and MWF applications can be derived. In addition, detailed experimental analyses of MWFs provide essential data for the input and validation of model development and numerical simulations within the Priority Programme SPP 2231 FluSimPro.

The simulation of machining processes holds the opportunity for process improvement on many levels. Possible benefits that can be derived from accurate representations of the real processes on the tool from simulations include a prediction of tool wear, the shape of the chips produced, the forces, frictions and temperatures that arise and the residual stresses in the workpiece. These predictions can be used to improve the process in terms of its economic and ecological behaviour: Increasing the service life of the tools used through an improved understanding of the tool-workpiece interaction. The finite element method (FEM), among others, has emerged as a common method for simulating these processes. When simulating machining processes using FEM, a major challenge is to avoid or compensate for the mesh distortions caused by the massive, fast-moving deformation processes, but at the same time to allow the mesh to be discretised in some way to ensure chip removal. To this end, various approaches will be presented in the course of this work and the mesh-based approaches will be explored in depth. Among other things, a remeshing approach for these investigations was developed. The machining of TI6AL4V is used to illustrate these approaches, as its tendency to form segmented chips is particularly challenging to model.

Circular sawing is an important intermediate step in industrial production. Due to the increasing demand for high-performance materials such as titanium alloys, efficient manufacturing for such difficult-to-machine materials is becoming more and more important. Traditionally, large quantities of cutting fluid are supplied to the sawing process by means of flood lubrication. However, the application of cutting fluids is expensive and energy-intensive. Additionally, cutting fluids pollute the environment and are harmful to health. The aim should therefore be to develop resource-saving machining processes and to reduce the need for cutting fluids in a sustainable manner. During sawing, a saw kerf is created which makes it difficult to supply the cutting process with cutting fluid. Chip formation plays an important role in the circular sawing process. This paper shows that by using a transparent kerf, the chip deformation can be studied and evaluated using a high-speed camera. By investigating the chip diameter from the camera recordings, the filling of the saw tooth gullet can be evaluated. As main result of the investigation an internal coolant supply in circular sawing can reduce the volume flow by 50% and improve the chip deformation process at the same time. This allows a sustainable and resource-efficient design of sawing processes.

To improve machining processes concerning the usage of lubricants, knowledge of the thermo-mechanical and thermo-fluid interactions at the cutting zone is of great importance. This study focuses on the description of the convective heat transfer which occurs during circular sawing when the lubricant is provided via an internal coolant supply. The highly complex flow field inside the cavity of the sawing process is separated into two distinct flow forms, an impingement and a channel flow. With the aid of experimental and numerical studies, the heat transfer characteristics of these two flow forms have been examined for water and a lubricant used in the circular sawing process. Studies have been conducted over a wide range of Reynolds numbers (impingement flow: $2\times {10}^3<\mathrm{Re}<17\times {10}^3$, channel flow: $1\times {10}^3<\mathrm{Re}<30\times {10}^3$). Additionally, the variation in the inlet temperature of the fluid, as well as the variation in heating power, has been studied. Overall, the impingement flow yields a significantly higher heat transfer than the channel flow with Nußelt-numbers ranging from 120 to 230, whereas the Nußelt-numbers in the case of the channel flow range from 20 to 160. For both flow forms, the use of the lubricant results in a better heat transfer compared with the usage of water. With the aid of these studies, correlations to describe the heat transfer have been derived. The provided correlations are to be used in a coupled numerical model of the chip formation process which also includes the effects of the heat transfer to the coolant lubricant.