@article{TroeberHacklLeitneretal.2023, author = {Tr{\"o}ber, Philipp and Hackl, Alfred and Leitner, Harald and Welm, Markus and Demmel, Peter and Golle, Matthias and Volk, Wolfram}, title = {On the Sensitivity of a Tool-Workpiece Thermocouple to Chemical Composition and Microstructure}, volume = {94}, pages = {2200456}, journal = {Steel research international}, number = {4}, publisher = {Wiley}, address = {Weinheim}, issn = {1869-344X}, doi = {https://doi.org/10.1002/srin.202200456}, year = {2023}, abstract = {Meeting the increasing demands on part quality and profitability of manufacturing processes despite difficult-to-machine materials is only possible with a deep understanding of the process. Herein, knowledge about the process temperature is of critical importance since it affects the material properties, such as hardness or forming behavior, as well as the chemical and physical interactions between the tool, workpiece, and lubricant. A proven thermoelectric method of temperature measurement in machining, forming, and blanking is a tool-workpiece thermocouple. Herein, instantaneous measurement of the temperature development is allowed in this setup during the manufacturing process in situ at the contact area of the tool and workpiece. The accuracy of this method is dependent on the calibration of the thermocouple, for which the Seebeck coefficients of the tool and workpiece material have to be determined. Usually, material samples from different batches are used for this purpose, although the resulting measurement errors due to slight changes in material properties are hardly known. The effects of small changes in the chemical composition and the transformation of the crystal lattice due to hardening on the Seebeck coefficient are investigated for the first time to allow precise quantification of the measurement error resulting from the calibration process.}, language = {en} } @article{WelmKindsmuellerTroeberetal.2023, author = {Welm, Markus and Kindsm{\"u}ller, Alexander and Tr{\"o}ber, Philipp and Dr{\"o}se, Lukas and Volk, Wolfram}, title = {Stresses between die and slug in blanking and their significance for slug pulling}, volume = {17}, journal = {Production Engineering: Research and Development}, number = {6}, publisher = {Springer}, address = {Berlin}, issn = {1863-7353}, doi = {https://doi.org/10.1007/s11740-023-01202-w}, pages = {875 -- 882}, year = {2023}, abstract = {The primary goal when manufacturing components in a blanking process is a high output to achieve good cost efficiency. Therefore, availability needs to be as high as possible. However, several process disturbances like slug pulling increase downtime and thus counteract this aim. Slug pulling is influenced by different forces that trigger the slug being pulled and those that hamper this effect. The predominating hampering force is friction between the slug and the die. Consequently, the influencing factors for this force have to be understood to reliably prevent slug pulling. In this publication, the influence of the die channel geometry on the occurring frictional forces and the part quality when blanking the non-alloy quality steel 1.0338 are investigated. Therefore, experiments with a variation of die channel geometry and punch diameter combined with force measurement are performed. Furthermore, a numeric simulation model based on the experimental results is used to investigate various die channels. The results enhance the knowledge about correlations between process parameters, slug properties, like slug deflection, and frictional forces and help to reliably prevent slug pulling.}, language = {en} } @article{PaetzoldTroeberWelmetal.2022, author = {P{\"a}tzold, Isabella and Tr{\"o}ber, Philipp and Welm, Markus and Volk, Wolfram}, title = {Blanking of Stainless Steel}, volume = {2022}, pages = {012030}, journal = {IOP Conference Series: Materials Science and Engineering}, number = {1238}, publisher = {IOP}, address = {Bristol}, issn = {1757-899X}, doi = {https://doi.org/10.1088/1757-899x/1238/1/012030}, year = {2022}, abstract = {Slug pulling, adhesion formation and edge fracture are major challenges in the sheet metal processing industry. They lead to a strong reduction in part quality, process stability as well as profitability. In this study, investigations are carried out on stainless steel X5CrNi18-10 to address the previous mentioned challenges. While slug pulling and edge fracture strongly depend on the geometric characteristics of active elements as well as the selection of process parameters, adhesion formation is mainly determined by temperature and thermoelectric currents. In this publication, the influence of the die channel geometry on the slug pulling effect and the part quality is investigated. Furthermore, the temperature profile over the shear cutting process as well as the resulting thermoelectric currents are determined for the test material. The relationship between edge crack sensitivity, shear cutting parameters and strategies is examined. These investigations thus form the basis for an improved understanding of the shear cutting of stainless steel.}, language = {en} } @article{LandesbergerKoosHofmannetal.2020, author = {Landesberger, Martin and Koos, Robert and Hofmann, Michael and Li, Xiaohu and Boll, Torben and Petry, Winfried and Volk, Wolfram}, title = {Phase Transition Kinetics in Austempered Ductile Iron (ADI) with Regard to Mo Content}, volume = {13}, pages = {5266}, journal = {Materials}, number = {22}, publisher = {MDPI}, address = {Basel}, issn = {1996-1944}, doi = {https://doi.org/10.3390/ma13225266}, year = {2020}, abstract = {The phase transformation to ausferrite during austempered ductile iron (ADI) heat treatment can be significantly influenced by the alloying element Mo. Utilizing neutron diffraction, the phase transformation from austenite to ausferrite was monitored in-situ during the heat treatment. In addition to the phase volume fractions, the carbon enrichment of retained austenite was investigated. The results from neutron diffraction were compared to the macroscopic length change from dilatometer measurements. They show that the dilatometer data are only of limited use for the investigation of ausferrite formation. However, they allow deriving the time of maximum carbon accumulation in the retained austenite. In addition, the transformation of austenite during ausferritization was investigated using metallographic methods. Finally, the distribution of the alloying elements in the vicinity of the austenite/ferrite interface zone was shown by atom probe tomography (APT) measurements. C and Mn were enriched within the interface, while Si concentration was reduced. The Mo concentration in ferrite, interface and austentite stayed at the same level. The delay of austenite decay during Stage II reaction caused by Mo was studied in detail at 400 °C for the initial material as well as for 0.25 mass \% and 0.50 mass \% Mo additions.}, language = {en} } @article{TroeberWelmWeissetal.2019, author = {Tr{\"o}ber, Philipp and Welm, Markus and Weiss, Hannes Alois and Demmel, Peter and Golle, Roland and Volk, Wolfram}, title = {The influence of process parameters and sheet material on the temperature development in the forming zone}, volume = {6}, pages = {9}, journal = {Manufacturing Review}, publisher = {EDP Sciences}, address = {Les Ulis}, issn = {2265-4224}, doi = {https://doi.org/10.1051/mfreview/2019005}, year = {2019}, abstract = {Cold metal forming is a fast and economical way of producing a wide range of precise components. Its profitability mainly depends on part quality, process stability, and service intervals of tools. As these factors are all determined by tool wear, detailed process knowledge is indispensable to maximize profitability by minimizing wear. One of the most crucial factors in this context is temperature. During every forming process, a temperature rise occurs between tool and workpiece due to frictional heating and a large part of plastic work dissipating into heat. This phenomenon affects the whole forming process but especially tool wear. Currently, there is little solid information about temperatures occurring during forming operations. Therefore, the temperature was measured based on varying process parameters, sheet materials, and thicknesses in several embossing and blanking examinations. The use of a tool-workpiece thermocouple enabled accurate and instantaneous measurement during the process. The results presented show the strong influence of process and material parameters on temperatures in the forming zone.}, language = {en} } @article{WelmTroeberWeissetal.2020, author = {Welm, Markus and Tr{\"o}ber, Philipp and Weiss, Hannes Alois and Demmel, Peter and Golle, Roland and Volk, Wolfram}, title = {Thermoelectrically Based Approaches to Reduce Adhesive Wear During Blanking}, volume = {72}, journal = {JOM}, number = {7}, publisher = {Springer}, address = {New York}, issn = {1543-1851}, doi = {https://doi.org/10.1007/s11837-020-04191-8}, pages = {2525 -- 2535}, year = {2020}, abstract = {Almost every metal mass product goes through a blanking process. Especially when processing aluminum, adhesive wear is the main determinant of cost efficiency. Many investigations on wear-influencing factors have been conducted so far, but one major determinant is almost unnoticed, thermoelectric phenomena. Due to the Seebeck effect, thermoelectricity arises in every blanking tool. Recently published investigations show that the combination of tool and workpiece materials has a strong influence on occurring thermoelectric currents and thus on adhesive wear development. This can be traced back to dependence of the current strength and direction on the material-specific Seebeck coefficient. This article addresses the same phenomenon for a new parameter spectrum. Blanking experiments with aluminum EN AW 5083 were performed, investigating both thermoelectric currents and the amount of adhesive wear. Furthermore, the impact of external currents influencing the naturally occurring thermoelectricity on wear is shown. Improved measurements with a laser confocal microscope reveal a close correlation between the thermoelectric current profiles and adhesive wear pattern on the lateral surface of the punch. Together with a variation of tool material among high-speed steel 1.3343, stainless steel 1.4301 and cemented carbide CF-H40S, a strong relation between the Seebeck coefficients, electrical currents and tool wear could be found. Therefore, the actual findings confirm, deepen and extend previous results concerning thermoelectricity and adhesive wear.}, language = {en} } @inproceedings{WelmTroeberWeissetal.2020, author = {Welm, Markus and Tr{\"o}ber, Philipp and Weiss, Hannes Alois and Demmel, Peter and Golle, Roland and Volk, Wolfram}, title = {A Thermoelectrically Based Approach to Reduce Adhesive Wear During Blanking}, booktitle = {TMS 2020 149th Annual Meeting \& Exhibition Supplemental Proceedings}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-36298-0}, doi = {https://doi.org/10.1007/978-3-030-36296-6_183}, pages = {1993 -- 2007}, year = {2020}, language = {en} } @article{LandesbergerKoosErberetal.2020, author = {Landesberger, Martin and Koos, Robert and Erber, Maximilian and Pernumian, Matteo and Masaggia, Stefano and Hoelzel, Markus and Volk, Wolfram}, title = {Phase transition and microstructure investigation of perferritic isothermed ductile iron (IDI)}, volume = {33}, journal = {International Journal of Cast Metals Research}, number = {6}, publisher = {Taylor \& Francis}, address = {London}, issn = {1364-0461}, doi = {https://doi.org/10.1080/13640461.2020.1833477}, pages = {233 -- 241}, year = {2020}, language = {en} } @article{SchrepferSchottTroeberetal.2022, author = {Schrepfer, A and Schott, A and Tr{\"o}ber, Philipp and Keunecke, M and Welm, M and Steinlehner, F and Golle, R and Volk, Wolfram}, title = {Reduction of adhesive wear with use of tool coating reducing thermoelectric currents}, volume = {2024}, pages = {012033}, journal = {IOP Conference Series: Materials Science and Engineering}, number = {1238}, publisher = {IOP Publishing}, address = {London}, issn = {1757-8981}, doi = {https://doi.org/10.1088/1757-899x/1238/1/012033}, year = {2022}, abstract = {Blanking is one of the main processes in producing sheet metal components. The impact of adhesive wear of the blanking tools on the cost efficiency is high, especially when processing aluminum. As an influencing factor on adhesive wear in blanking, thermoelectric currents have been considered to a very small extent. Recent investigations have shown that thermoelectric currents occur in every blanking tool due to the rise of temperature in the shear zone in interaction with a difference of the material-specific Seebeck coefficients of tool and sheet metal. A reduction in the amount of wear was observed in case of a smaller difference of Seebeck coefficients and therefore lower levels of flowing thermoelectric currents. This paper follows the approach of adjusting the Seebeck coefficient of the tool material CF-H40S+ to the one of the sheet material by means of coating with CrAlN, in order to reduce the flowing thermoelectric currents and consequently adhesive wear. For this purpose, the effect of coating on the Seebeck coefficients, the thermoelectric currents during blanking as well as resulting wear quantities were investigated. Basic correlations could be revealed.}, language = {en} } @article{PrueferWeisserGlushychetal.2025, author = {Pr{\"u}fer, Kevin and Weisser, Eduard and Glushych, Viktor and Tr{\"o}ber, Philipp and Hartmann, Christoph and Volk, Wolfram}, title = {Seebeck Coefficient Modification via Extreme High-Speed Laser Material Deposition for Tool Materials}, volume = {2025}, journal = {Procedia CIRP}, number = {137}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2212-8271}, doi = {https://doi.org/10.1016/j.procir.2025.02.265}, pages = {265 -- 270}, year = {2025}, abstract = {During blanking and cold forming of metals, thermoelectricity almost always occurs. While thermoelectric voltages can be used for temperature measurement via a tool-workpiece thermocouple, currents significantly influence adhesion formation. In both cases, the thermoelectric behavior of tool and workpiece materials, characterized by the Seebeck coefficient, plays a decisive role. While a large difference in coefficients increases the accuracy of temperature measurement, similar coefficients improve wear behavior. Currently, there is no method to adjust the Seebeck coefficient of materials without experimental procedures, which restricts the selection of tool materials based on their Seebeck coefficient. This study presents a novel approach for adjusting the Seebeck coefficient of tool steels using tailored coatings applied by extreme high-speed laser material deposition (EHLA). Therefore, an analysis was conducted to investigate the effects of chemical composition, substrate material and its heat treatment on the thermoelectric and mechanical behavior of the coating. The results demonstrate that targeted modification via tailored EHLA coatings is possible.}, language = {en} }