ZELTWANGER optimizes the production of fin heat exchangers

ZELTWANGER Thermomanagement GmbH & Co. KG, a company within the ZELTWANGER Group based in Tübingen, manufactures, among other things, fin forming machines for the production of heat exchanger fins. A key process in this production is the lubrication of the raw material to extend the lifespan of the forming rollers. To optimize this step, the Tübingen-based company has developed a retrofittable stand-alone lubrication unit.

Fin heat exchangers are used in numerous technical systems, such as building heating systems, air conditioning units, and production plants across various industries. Additional key applications include vehicles, such as front radiators, air conditioning systems, and increasingly, cooling systems for drive batteries. Due to the high production volumes, the automotive sector remains a core market for heat exchanger experts. Aluminum has become the material of choice in this field, typically processed as coil stock. High-performance fin forming machines use specialized rolling tools (fin form rolls) to create the characteristic wavy contours of the fins. The band speed can reach up to 6.5 m/s. To ensure a long lifespan for the rollers, a layer of lubricating oil is applied. However, since the fins are later brazed during assembly, this oil must be completely removed after forming. This is achieved by evaporation, necessitating the use of a special evaporative oil.

Wladimir Leimann, Business Unit Manager at ZELTWANGER Thermomanagement, emphasizes: “Our new lubrication unit applies only as much oil as absolutely necessary. We refer to this as minimum quantity lubrication. This ensures the quality of the brazed joints. We also opted for a stand-alone solution that can be integrated into any existing fin forming machine. Therefore, our technology is accessible to all manufacturers of heat exchanger fins.”

The concept of ZELTWANGER and its advantages in detail: Two adjustable atomizing nozzles spray the coil material from both sides. The experts from Tübingen adjust the nozzles precisely to the existing oil (viscosity, density). This means that the user is provided with a pre-adjusted system. The lubrication unit also automatically adjusts the spray width and oil quantity based on the stored coil width and the current speed to ensure uniform coating, support optimal brazing results, and maintain efficient oil consumption.

Regarding oil supply, the user has complete flexibility. The unit can be filled manually using a funnel, via an electric drum pump with a drip-free quick coupling, or through an existing plant pipeline. In all cases, refilling can be done during production without the need to stop the machine. A key advantage: no pressurized tank is required, as the oil is transported by a mechanical pump. Consequently, no oil mist is generated that would require extraction. This keeps the workspace clean and eliminates additional costs. Furthermore, any minimal overspray is captured by a filter and remains within the circulation system. The bottom line is that oil consumption is reduced by up to 70%. The same applies to material consumption.

The flexibility of the lubrication unit extends even further. It is not only suitable for aluminum and its specific requirements but can also be used for materials such as stainless steel or copper. The relevant parameters can be easily adjusted via the HMI (Human-Machine Interface). Additionally, integration into tube seaming or tube welding machines is also possible.

Footage

Figure 1: Example of heat exchanger fins

Figure 2: Lubrication unit