Browsing by Author "Menze, Christian"

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Open Access
Assessment of the heat transfer conditions in the cavity of a rotating circular saw
(2024) Stegmann, Jan; Baumert, Moritz; Kabelac, Stephan; Menze, Christian; Ramme, Johannes; Möhring, Hans-Christian
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: 2×103
Open Access
Determination of the tool-chip contact length for the cutting processes
(2022) Storchak, Michael; Drewle, Konstantin; Menze, Christian; Stehle, Thomas; Möhring, Hans-Christian
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.
Open Access
Evaluation of methods for measuring tool-chip contact length in wet machining using different approaches (microtextured tool, in-situ visualization and restricted contact tool)
(2022) Ellersiek, Lars; Menze, Christian; Sauer, Florian; Denkena, Berend; Möhring, Hans-Christian; Schulze, Volker
The contact length is one of the most important factors to evaluate the chip formation process and the mechanical loads in metal cutting. Over the years, several methods to identify the contact length were developed. However, especially for wet cutting processes the determination of the contact length is still challenging. In this paper, three methods to identify the contact length for dry and wet processes in cutting of Ti6Al4V and AISI4140 + QT are presented, discussed and analyzed. The first approach uses tools with a microtextured rake face. By evaluating the microstructures on the chip, a new method to identify the contact length is established. The second approach applies high speed recordings to identify the contact length. The challenge is thereby the application of high-speed recordings under wet conditions. In the third approach, tools with restricted contact length are used. It is shown that with all three methods the contact length is reduced using metal working fluid.
Open Access
Flow visualisation and evaluation studies on metalworking fluid applications in manufacturing processes : methods and results
(2023) Fritsching, Udo; Buss, Lizoel; Tonn, Teresa; Schumski, Lukas; Gakovi, Jurgen; Hatscher, Johnson David; Sölter, Jens; Avila, Kerstin; Karpuschewski, Bernhard; Gerken, Julian Frederic; Wolf, Tobias; Biermann, Dirk; Menze, Christian; Möhring, Hans-Christian; Tchoupe, Elio; Heidemanns, Lukas; Herrig, Tim; Klink, Andreas; Nabbout, Kaissar; Sommerfeld, Martin; Luther, Fabian; Schaarschmidt, Ingo; Schubert, Andreas; Richter, Markus
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.
Open Access
Fundamental characterization of lubrication effects through various cooling lubricants in the chip formation zone
(2025) Biermann, Dirk; Saelzer, Jannis; Bergmann, Benjamin; Schenzel, J.; Menze, Christian; Gerken, Julian Frederic; Wolf, T.; Denkena, Berend; Möhring, Hans-Christian; Zabel, Andreas
Using cooling lubricants in metalworking requires a high consumption of energy and resources. However, cooling lubricants serve to increase the productivity and quality of these processes. Accordingly, it is necessary to expand the efficiency of their application. This requires fundamental understanding of the working mechanisms. Driven by this motivation, this publication compares six cooling lubricants regarding their lubrication effect in orthogonal cutting. Three types of fluid supply, each conducted on a specific special machine tool for chip formation analysis, and two cutting speeds have been used in the tests. In order to analyze the lubricating effect of these different scenarios, force measurements were carried out and the chip formation was recorded with high-speed recordings. It was found that the process improvements due to lubrication is determined by the interaction of fluid properties, supply strategy and cutting speed. Moreover, clear limitations of water-based cooling lubricants (especially oil-water-emulsions) in the ability to lubricate the chip formation zone have been determined and quantified.