Induction heating system scores points in motor production at Elektror

The component sizes change on a very regular basis. That is why the UNI HEAT is very easy to retool. Elektror has various sizes of inductors available for the empty stator housings. (Courtesy: EMAG)

Elektror airsystems is one of the international leaders in the production of industrial fans and side channel compressors.

Elektror has been relying on UNI HEAT from EMAG eldec since mid-2018 for the production of the electric motors used in its fans. The system ensures quick and precise induction heating of the empty stator housing before the joining process with the motor winding. The process reliability and flexibility of the entire sequence are essential for the rapid “one-piece-flow” at Elektror.

Many industrial production processes wouldn’t be possible without fans — they play a decisive role in the drying, suction, or cooling of materials. Often the stability and efficiency of the entire production process may even be dependent on the fans used.

Air is an indispensable working medium in industrial production. It is used, for example, to extract excess humidity or dust, cool down heated materials, remove occurring gases and vapors or transport solids in an air flow. That means fans not only constitute the centerpiece of the corresponding ventilation system, but they are also exposed to extreme pressures and are relied on for decades — a set of challenges that Elektror airsystems has been facing for many years.

The company headquartered in Ostfildern, Germany, and with two production sites in Waghäusel (Germany) and Chorzów (Poland), produces about 60,000 industrial fans and side channel compressors per year. These are often customized solutions that stand out, for example, because of a precise pressure level, resistant materials, or a particularly low-vibration design. In the end, there are countless customization options available when designing a fan — and that obviously also applies to the devices’ electric drives. That is why Elektror produces different size motors and performance levels. Its components are configured to order and mounted within the scope of a lean process. In doing so, the ventilation specialists place the highest importance on process reliability. Fault tolerance is always set to “zero.”

In this process, thermal joining of the empty stator housing and motor winding is one of the core processes. The housing is heated to a temperature of 280 to 300°C (536 – 572°F) using an induction heating system. This causes it to expand, allowing the motor winding to be inserted by hand. As it cools down, the housing contracts again and establishes a form-fitting and solid bond with the winding. In 2018, the specialists at Elektror decided it was time to replace the aging heating system.

“One of our main goals in making the investment decision was to increase process reliability around induction heating. For instance, the old system did not display the actual processing temperature that the component had reached. This led to longer throughput times in the subsequent joining operation. Furthermore, the supply of spare parts was not secured,” said Roland Sand, head of the production team at Elektror. “Therefore, we were searching for a system that guarantees very precise temperatures during heating, whose operation is straightforward for any operator and whose processes consistently run. Additionally, we wanted a local supplier who could be on location immediately when servicing is required. EMAG eldec meets these requirements with its UNI HEAT technology.”

Overall, a very safe and quick process is put into effect around the custom-designed UNI HEAT system: The operator grabs the empty housing with protective gloves, places it in a custom-fit workpiece carrier and pushes it inside the machine. By closing a sliding door, he starts the following process: The component moves upward into its home position. This leads the induction rod to “plunge” into the empty housing enclosure. The subsequent heating process lasts only 30 to 120 seconds depending on the size of the component. Once it is completed, a warning lamp signals to the operator that the component can be removed. He places it in a mold, which is ready at the cooling location, and pushes the motor winding from the top inside. After a short cooling process, the motor is fully combined and ends up on a conveyor belt to the next processing step.

“We produce about 250 motors per day in this way,” said Steffen Müller from quality assurance at Elektror. “The component sizes change regularly and yet the process stays perfectly stable. There are absolutely no issues or faults.” Which is partially due to how simple it is to retool the machine in the event of a component change: The operator closes the water supply, loosens two screws on the inductor mount and can then remove the tool and replace it with a new one. The workpiece holder is merely set down and can, therefore, easily be removed from its support and replaced.

“Including the program change on the control module, the entire retooling process lasts only about one minute. Various safety features prevent operator errors,” Müller said.

Development at EMAG eldec plays a decisive role for the quality, safety and efficiency of this induction heating process: The induction specialists take responsibility for complete solutions — including the appropriate generator and the required inductors.

EMAG eldec is ideally positioned to develop these core elements of a heating process: Firstly, a wide range of generators with high efficiency and precise application of energy are produced at the site in Dornstetten. Secondly, the specialists produce up to 1,000 inductors per year. They are produced within the scope of a sophisticated manufacturing process that hinges on many tiny details. Critical factors include, for example, how deep and where the heat needs to penetrate into the component. That affects the shape of the inductor and the configuration of the generator. Furthermore, EMAG eldec relies on extensive prior simulation of the process and the use of thermal imaging cameras. Lastly, every UNI HEAT overall solution is tested with the real workpiece and presented to the customer during an acceptance check in Dornstetten.

“Since the start of production in May 2018, there have been absolutely no faults,” Sand said. “The eldec service team quickly rectified any minor startup problems. This investment decision meets our expectations in all aspects.”