The SKF plant in Chodov produces progressive distributors for lubrication systems, among other things. However, problems occurred in the previous production line. There were repeated blockages caused by residual dirt in internally cooled tools. In the relatively slow machines previously used, single-position solutions were used as a filter variant. The SKF Manufacturing Technology project team, led by Steffen Siegemund, was given the task of ensuring that production in Chodov is more flexible, of higher quality and at lower cost. The decision was therefore made to purchase fast single-spindle milling centers.

Martin Zverina, Operations Manager SKF

The SKF project team and Global Purchasing contacted Mayfran in Aachen to clarify the question of how chips can be efficiently processed, cooling lubricant recovered and fed back into the production process. Together with the specialist for chip conveyors and filter systems, they evaluated the advantages and disadvantages of stand-alone and isolated solutions as well as centralized supply in a concept comparison. The decision was ultimately made in favor of a modular stand-alone system with a chip conveyor.

The filter system serves two production lines with three machine tools each and a single workstation solution. The system performs full-flow cleaning of chips down to a size of 25 µm plus a second fine filter stage (bypass cleaning) using paper belt filters down to 5 µm. The system is equipped with a secondary protection tank and complies with the provisions of the German Water Resources Act (WHG). It also has an immersion cooler. The SKF plant is thus prepared for increasing quantities and can switch on this cooler as required to keep the cooling lubricant at a constant process temperature.

Support from within our own ranks

The third missing link was a suitable pump manufacturer. The SKF project team found what it was looking for within its own ranks. Spandau Pumpen, based in Berlin, has been part of the SKF Group since 2004. The company develops and builds high-performance solutions for centralized supply and disposal as well as processing around the machine tool. "Spandau Pumpen is an independent brand within the SKF Group, so it was clear to rely on products from our own company," says Martin Zverina, plant manager in Chodov.

For the modular island solution with chip conveyor, the Berlin-based company supplied three low-pressure and three high-pressure pumps, each with frequency converters (FC), for the machining process. The commercially available motors used can be easily upgraded with a frequency converter using an adapter concept. The pumps with inverters are operated in parallel, thus reducing the control engineering effort and also increasing operational reliability. Some components are designed redundantly to prevent system failures.