Eldec Schwenk Induction GmbH

Dornstetten, Germany

Eldec Schwenk Induction GmbH

Dornstetten, Germany
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Stiele H.,EFD Induction GmbH | Krause C.,Eldec Schwenk Induction GmbH
Elektrowaerme International | Year: 2013

Using surface hardening processes (flame-, induction, laser-, electron beam hardening) normally a fraction of the work piece volume is austenized. This happens usually with high heating rates compared to a heating by furnace. This is the reason why the term short time austenitization is closely connected to the methods of surface hardening. In the following article the metallurgical processes and the characteristics during fast heating and short soaking times are described.


Krause C.,Eldec Schwenk Induction GmbH | Biasutti F.,Eldec Schwenk Induction GmbH | Davis M.,eldec Induction United States
American Gear Manufacturers Association Fall Technical Meeting 2011 | Year: 2011

Induction hardening of gear teeth is a well known for its challenges, but also for its potential for improved quality and process control. For complex geometric parts like gears, the power density and induction frequency need to be adjusted very precisely to achieve the required hardening pattern. Since the 1940s, it is well known that working with two simultaneous frequencies is the optimal way to heat a geared part up to hardening temperature. The key point in this process is that the medium frequency (about 10 kHz) affects primarily the tooth root and the high frequency affects first of all the tip of the tooth and the flanks. The right combination of the power densities of medium- and high frequency energy values and the heating time are the crucial factors to reach a contour true heating pattern and, thereby, a contour true hardening pattern. Short heating times and high power densities are critical relevant factors in order to achieve contour true hardened gears. While the benefits are known, the practical combination of medium and high frequency induction are electromechanically restricted and difficult to achieve. Today we are able to get benefits from this process using SDF® technology with high power density (up to 8 kW/cm ). A big benefit is the flexibility. The user is able to manipulate the intensity of the heat sources by manipulating the power ratio of the two frequencies. This gives us the possibility to achieve a special hardening pattern on a specific gear geometry. If we want to heat treat different gear geometry we can change power ratio and heating time to reach the designated hardening pattern. To get a contour true hardening pattern, a short heating time is necessary to prevent heat conduction into the remainder of the part. Usually the heating times are between 100 and 500 milliseconds. Today SDF®-generators are able to exactly control the energy value in these time frames. We can reduce the distortion that occurs from heat treatment because of the smaller volume of material (HAZ) affected by induction heating with ultra-short short heating times. The authors will describe the state of the art of induction hardening of gears with simultaneous dual frequency using case studies which show the possibilities to manipulate the hardening pattern in a positive way for different desired gear geometries.


Gretzki T.,Leibniz University of Hanover | Rodman D.,Leibniz University of Hanover | Wolf L.,Leibniz University of Hanover | Dalinger A.,Leibniz University of Hanover | And 3 more authors.
HTM - Haerterei-Technische Mitteilungen | Year: 2011

The objective of the current investigation is a cost analysis of spray cooling based on the assessment of a machine-hour schedule.Here, a gear toothed component is used as an example which is induction hardened by means of the simultaneous dual frequency method and compared with conventional polymer quenching. By using hardness measurements and light-microscope examinations, it is demonstrated that comparable results are obtained for the induction hardening by employing spray cooling and those by polymer quenching. By investigating the influence of the spray's parameters on the hardness results, it was possible to draw inferences regarding the ratios of water to air pressures which lead to the desired hardness profiles. Estimating the costs of employing the two quenching methods have shown that the spray cooling is the more cost-effective of the two methods.


Rodman D.,Leibniz University of Hanover | Nurnberger F.,Leibniz University of Hanover | Dalinger A.,Leibniz University of Hanover | Schaper M.,Leibniz University of Hanover | And 3 more authors.
Steel Research International | Year: 2014

Induction hardening is a surface hardening process in which severe temperature gradients occur due to limiting the heating to the sub-surface layer. High residual stresses result from these gradients, which can negatively influence the fatigue strength and induce cracking. To reduce the residual stresses, induction hardening is followed by a tempering, which is usually carried out for several hours in a furnace. Substituting furnace tempering by tempering from the residual heat motivated the current investigations. During induction hardening of helical gearwheels made of 42CrMo4 heat-treating steel using a controlled quenching by means of spray cooling, an additional tempering from the residual heat was performed. The result of the heat treatment was analyzed with the aid of hardness, residual stress, and distortion measurements. The obtained hardening results demonstrate the equivalence of the two tempering processes considered here. During induction hardening of helical gearwheels made of 42CrMo4 heat-treating steel using spray cooling, a self-tempering was performed. The result of the heat treatment was analyzed with the aid of hardness, residual stress, and distortion measurements. The obtained hardening results demonstrate the equivalence of self-tempering and conventional furnace tempering. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Krause Ch.,Eldec Schwenk Induction GmbH | Springer R.,Leibniz University of Hanover | Biasutti F.,Eldec Schwenk Induction GmbH | Gershteyn G.,Leibniz University of Hanover | Bach Fr.-W.,Leibniz University of Hanover
HTM - Haerterei-Technische Mitteilungen | Year: 2010

The steel Cf 53 (material number 1.1213) is used for induction surface hardening of different gear box parts like shafts and gears. The material is characterised by a small amount of alloys and a good natured behaviour considering the residual stress during the heat treatment and the crack sensitivity. By carrying out the transformation behaviour of this material, using induction surface hardening, an inhomogeneous microstructure occurred. This article describes the analysis of these microstructural defects. Beside the optical microscopy the transmission electron microscopy was used for the observation of the sample. The martensitic as well as the defect domains were identified and analysed. © 2010 Carl Hanser Verlag, München.


Rodman D.,Leibniz University of Hanover | Krause C.,Eldec Schwenk Induction GmbH | Nurnberger F.,Leibniz University of Hanover | Bach F.-W.,Leibniz University of Hanover | And 2 more authors.
International Journal of Materials Research | Year: 2012

The objective of the current investigation consists of testing the interchangeability of polymer solutions used during induction hardening with water-air spraying regarding compressive residual stresses. Gearwheels made of 42CrMo4 steel were induction hardened and subsequently quenched using water-air spray cooling. The effect of different cooling parameters on the surface's residual stresses in the gearwheel's tooth flanks was analysed by means of X-ray diffraction. The microstructure was characterised by means of hardness measurements and light-microscopy. Residual stresses could be specified after using water-air spray cooling and are comparable to those using polymer quenching. Quench parameters leading to maximum compressive residual stresses in tooth flanks were determined. © 2012 Carl Hanser Verlag GmbH & Co. KG.


Rodman D.,Leibniz University of Hanover | Krause C.,Eldec Schwenk Induction GmbH | Nurnberger F.,Leibniz University of Hanover | Bach F.-W.,Leibniz University of Hanover | And 3 more authors.
Steel Research International | Year: 2011

As a rule, induction surface hardening is carried out industrially by employing polymer solutions since these ensure a more homogeneous quench than immersion cooling in water. Besides reproducing the quenching process, the intention here is to minimise the hardening defects and the distortions arising from the heat treatment. Polymer solutions also have a few disadvantages which include, among others, poor environmental compatibility and handleability. Quenching by means of spray cooling provides an effective alternative. The purpose of the current investigation is to substitute the polymer solution by a water-air spray in induction hardening equipment for surface hardening spur gearwheels made of 42CrMo4 hardening and tempering steel. The suitability of spray cooling was assessed by means of hardness measurements, residual stress conditions, distortion measurements and by metallographic examinations. Based on the analyses currently carried out, it was possible to show that the two-phase spray cooling represents an alternative quenching method which produces comparable component properties. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Krotz H.,Institute of Machine Tools and Manufacturing | Krotz H.,Eldec Schwenk Induction GmbH | Roth R.,Institute of Machine Tools and Manufacturing | Wegener K.,Institute of Machine Tools and Manufacturing
International Journal of Advanced Manufacturing Technology | Year: 2013

In this work, single discharges of electrochemical arc machining are examined. The heat-affected zone is analyzed, and a model is set up to simulate the heat transfer into the workpiece. As an input parameter of the simulation, the temperature of the electrochemical arc machining process was determined to be 3,500 K by means of emission spectroscopy. The simulation shows that the diameter of the heat-affected zone is less dependent on discharge duration and heat transfer due to heat flux than on the arc spot diameter. As a result of the investigation, it became clear that varying diameters of the heat-affected zone have to evolve from different diameters of the plasma channel's arc spot. Understanding the heat distribution into the workpiece in electrochemical arc machining with micro-machining parameters allows the further development of a micro-drilling process for electrically conductive materials based on electrochemical arc machining. © 2013 Springer-Verlag London.


Franze L.,Eldec Schwenk Induction GmbH | Krotz H.,Eldec Schwenk Induction GmbH | Krause C.,Eldec Schwenk Induction GmbH
Elektrowaerme International | Year: 2011

To achieve results in highest quality with induction surface hardening, it is not sufficient to internalize every single detail of material engineering. Furthermore, an induction hardening system has to be present, that is able to convert these demands coming from the idealized theory, into reality. The eldec Schwenk Induction Company is known to build such systems, where both, the machine, using a modular construction system, and the inverter are adjustable to any kind of hardening process.

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