Press  | 08/15/2017

Induction heating by eldec: Perfect machining temperatures guaranteed for welding

Welding processes are indispensable for the production of many components in car manufacturing. The procedure is becoming increasingly important, e.g. as many screws can be replaced with welded joints on automotive gearwheels. The weight and the material costs of the component are reduced as a result. Pre-heating plays an important role in many of these welding processes. It prevents the unwanted heating of the material structure in the heat-affected zone, the area directly surrounding the weld. That effectively prevents the risk of the formation of cracks in the component after welding to a large extent. However, the processing speed in modern automotive production represents a special challenge for heating processes: During an automated process, the component must reach a precisely defined temperature within only a few seconds. Induction heating by eldec is ideally suited for precisely this requirement: The EMAG company develops comprehensive solutions relating to the innovative procedure. The corresponding generators and inductors are tailored precisely to the component. Tests on the component provide an important basis. The result is a robust and energy-efficient solution that can easily be integrated into the production line.


Producing high quantities within seconds and without any processing errors – the central requirements in car manufacturing are an extreme challenge in particular for the welding of mass-produced components. To be able to ensure the required process reliability and efficiency, the procedure is integrated into an overall process that frequently ranges from inspection and washing processes to brush processing and the ultrasonic inspection of the weld. Immediately before the actual welding process, the precise heating of the component plays a decisive role, as Dr. Dirk Schlesselmann, Deputy Head of Application Technology Research and Development at eldec, explains. “The gearwheel or the piston must be heated precisely and at high speed to the required machining temperature of about 160 to 180 degrees Celsius. However, doing so must not cause any overheating of the component, which would result in the loss of hardness, oxidation or unacceptable deformation. In these conditions, induction heating is the ideal method, as it can be applied quickly and precisely and can be exactly dosed.”

Maintenance-free and efficient technology

The specialists at eldec have acquired exceptional expertise relating to induction heating processes integrated in higher-level welding systems for many decades now. At the location in Dornstetten, both the required generators and also the inductors are produced, using efficient manufacturing processes. The generators provide the benefit of very advanced power electronics and control technology. That makes it easy to integrate them in machines or configure them precisely according to requirements. The technology is also very reliable. “We build virtually maintenance-free converters that do their job quietly and reliably in the machine” summarizes Dr. Schlesselmann. On the other hand, the specialists integrate a great deal of experience in the development of inductors in the process - if desired, they already support the customers here at an early stage. Extensive research and tests are carried out on test inductors and generators. For example, thermographic imaging is used to check that only the desired areas of a component are heated. Since very recently, numerical calculations are also applied to be able to precisely determine the effect of an electromagnetic field in the component. “We effectively look inside the component”, explains Dr. Schlesselmann, “and subsequently adapt the geometry of the inductor and the performance class of the generator perfectly to the heating task.”  The eldec specialists offer medium and high-frequency generators from 1.5 to 1,500 kW as well as DF and SDF® generators from 50 to 3,000 kW. Devices can also have two to eight outputs whose power is controlled independently or simultaneously. This is a great advantage if several inductors are needed for heating, as they can be supplied from only a single generator. 


Getting everything out of the process 

The induction specialists have been very successful in the field of welding – to some extent with special key performance indicators. Today’s requirements for cycle times can be as low as five seconds. “With the methods mentioned, we try to get everything possible out of the process”, emphasizes Dr. Schlesselmann. “Then that could naturally mean that the heating phase needs to be extended to two cycles. However, our strength lies in finding this out and designing the process in such a way that it is as lean as possible.” The customer will then always have the benefit of a rapid machining time with higher heating rates. In addition, only a small component volume is heated. Incidentally, these are also the essential benefits compared to competitive methods, such as Uniform Magnetic Heating.

“For this reason, we are expecting significant market opportunities as the supplier of machine builders and other developers of welding production processes”, explains Dr. Schlesselmann finally. “The customer gets a technology that ensures the heating of the component faster and more efficiently than other solutions. In addition, we reduce the total expenditure in the customer’s R&D, as we can completely configure the heating process on our own at the request of the customer. These advantages will be successful on the market.”