StingR® – Field report from Gesau-Werkzeuge Fabrikations- und Service GmbH
Filtering HSS without compromise
With the StingR ultra-fine filter technology, Lehmann-UMT has developed a hydropneumatic backwashing process that offers the user a number of advantages. For the tool company Gesau-Werkzeuge, one thing is paramount: mastering a particularly difficult filtration process when grinding gear-cutting tools.
Cooling lubricants are a crucial component in the machining process; often, a machining task would not be possible without them. Thus, the cooling lubricant preparation is also an indispensable component in the process, since the cooling lubricant supply must be maintained in the required purity and at the necessary flow rate. In turn, the degree of purity of the cooling lubricant has a significant influence not only on process stability but also on the machining result and the wear of the cooling lubricant constituents. However, the right technology can only be selected and configured with a precise analysis of the machining process and its requirements. Gesau-Werkzeuge Fabrikations- und Service GmbH has consistently followed this path. The tool specialist from Glauchau-Gesau has completed the final stage of a metamorphosis in the cooling lubricant preparation that has been driven forward for years with Lehmann-UMT.
Producing and processing special tools
The fact that this path was unavoidable can be seen directly from the range of services offered by the tool specialist. Founded in 1980 as a workshop for the regrinding of cutting tools, the company concentrated on tools for metalworking from the 1990s onwards and, in this context, developed from a craft business into an industrial service provider. Today, Kerstin Milenkov, daughter of the company founder, and Ulf Köhler are the owner-managers of the 35-strong company. The production in Glauchau-Gesau concentrates on rotating, monolithic shank tools, preferably made of carbide and HSS, but also Cermet or CBN. Milling and drilling tools are thus just as much a part of the portfolio as semi-finished products and precision parts. „Among other things, we have specialized in elaborate tools with large aspect ratios,“ reports Ulf Köhler. However, Gesau-Werkzeuge also manufactures special products from CBN and Cermet. The second area of activity for the company is tool grinding as a service. „In this segment, we specialise in gear-cutting tools with a geometrically determined cutting edge and repair all tools that work on the tooth flank,“ says the managing director. Gear hobs, he states for example, are ground in all dimensions and constructive designs up to quality grade AAA. In addition to accuracy, another challenge in resharpening is the dimension of the tools. „In terms of broaching tools, our largest tools are 3 m long and weigh up to 500 kg.“
The challenge of corundum chip abrasion
This is also where Lehmann-UMT‘s filter technology is used for the preparation of gear-cutting tools. Why? Because it is a particularly delicate process: Some of the HSS tools have to be ground with dressable wheels, which results in a high amount of abrasive wear. Together with this corundum, the abrasion of HSS – which unlike carbide is a long-chipping material – forms a tough mass that places high demands on the filter technology. „That is why we went looking for a supplier that could handle these abrasion or contamination types with their filter technology,“ says Ulf Köhler. Up to this point, cooling lubricant preparation at Gesau-Werkzeuge has already undergone several stages of metamorphosis. Years earlier, the company invested in a centrifuge machine. With this central machine, however, they were limited to one type of cooling lubricant and had only a limited technological field of application at their disposal. It was a reliable wprocess, but lacked flexibility. In 2015, the tool specialist therefore began to decentralise again. A second circuit with a gap filter system was put into operation, which now filtered the cooling lubricant from the carbide grinding. „We immediately made a big leap in this area: in terms of quality, throughput and process reliability,“ reports production manager Frank Enderlein.
However, the corundum HSS mass remained a problem. „Here, we have four CNC machines that use dressable grinding wheels. For dressing them, we next wanted another cell, a third circuit that could handle this abrasion,“ says Ulf Köhler. „Today, we are at the finishing line of our metamorphosis and are using three cooling lubricant circuits: the large machine with centrifuge technology that handles mixed operations, the cartridge gap filter system designed for carbide machining, and the StingR system from Lehmann-UMT for the critical corundum/HSS slurry.“