When Oerlikon Barmag manufactures rotationally symmetrical components for high-tech spinning systems, high repeatable precision is required. Not every grinding machine can cope with that. Cylindrical grinding machines from Kellenberger ensure that not only the high accuracy requirements are met, but also those in terms of economic efficiency.
Maximum precision is a must at Oerlikon Barmag when components of spinning systems are to be manufactured
Oerlikon Barmag – a company of the Oerlikon Group headquartered in Remscheid, Germany, – sees itself as the world market leader in the development and production of spinning systems for the manufacture of filament yarns as well as texturing machines for yarn finishing. At the Remscheid site, around 800 employees manufacture components for the production of man-made fibers on more than 120 machine tools, such as extruders, winders, pumps, shafts, steel system housings, rotors and godets, i.e. rollers for drawing the synthetic fibers during the winding process, as well as special bearings for the godets. The material spectrum ranges from various types of steel to aluminum, cast iron and brass.
The demands on the components of the systems are high. From the raw material to the machining of the parts, the quality must be consistent. “We have acquired our manufacturing expertise over many years,” says Andreas Böttcher, responsible manufacturing manager at Oerlikon Barmag. “And we know what processing quality a machine must deliver to meet our demands. Our high-speed winders reach up to 8,000 m/min when winding fibers. That calls for maximum precision, performance and repeatability.”
An investment in grinding technology is always a matter of trust
A lack of precisely this quality had already led to a supplier change in the late nineties. For Böttcher, procuring a machine is also a matter of trust. That is why, when choosing a new grinding machine, he relied, among others, on a long-time companion. Holger Seitz had already been a competent advisor in the years before, when he was the responsible sales representative of grinding machine manufacturer Voumard. With the takeover of Voumard by the Swiss grinding machine manufacturer Kellenberger, Seitz was now also responsible for the Kellenberger portfolio.
Production manager Andreas Böttcher and Kellenberger sales representative Holger Seitz have jointly developed the innovative machining solution
Over the years, a total of five Voumard machines and almost a dozen Kellenberger cylindrical grinding machines, primarily of the VARIA and KEL-Vera series, were procured for the department headed by Andreas Böttcher. There, around 120 employees work in two and three shifts to produce technically demanding and safety-critical parts and core components for coil systems and godets. “We specialize in producing rotationally symmetrical parts with tolerances of 10 µm that can process synthetic fibers at speeds of up to 8,000 m/min,” explains Andreas Böttcher. “The Kellenberger machines achieve very high precision and repeatability due to their hydrostatic guides in all main axes and their precise measuring systems. They master the machining tasks with excellence, and the surface finish is so accurate that the need for regrinding and manual polishing work is now significantly lower.”
The KELLENBERGER 1000 has hydrostatic guides in all main axes which provide for very high shape accuracy in grinding tasks with interpolating axes
The required grinding length is increasing
The market is demanding ever longer and faster winding systems. As a result, the 1600 mm grinding length of the Kellenberger machines was at its limits, when in 2014 the machining of a take-up unit with 32-thread instead of 10-thread and a length of 1,930 mm was scheduled. A machine with a grinding length of 2,000 mm was not available in the Kellenberger portfolio. The purchase of a suitable machine from another manufacturer would have been much more expensive, and it would also result in an invest in larger grinding wheels. Böttcher passed the challenge on to Kellenberger’s Customized Special Design department. The design engineers there are always willing to put different approaches to the test. They came up with a solution using adjusted grinding wheels. To ensure that the required precision was achieved, grinding wheel supplier Theleico was brought on board. After just one week, the technical solution was ready on Böttcher’s desk. “We went down exactly this route and have been doing very well with it to date,” says Böttcher. “Once again, the expertise of the design engineers at Kellenberger was demonstrated, and the cooperation was extremely good, as always.”
The trust placed in the Swiss grinding specialist Kellenberger is evidenced by the fact that the machine park was again supplemented by a machine from thismanufacturer, this time a KELLENBERGER 1000
In 2018, another machine from Kellenberger was added to the machine park – again a VARIA universal cylindrical grinding machine, which now runs under the name KELLENBERGER 1000 in the Kellenberger portfolio. The machine stands for the highest machining and surface quality. The machine owes its success on the market to its high static and dynamic rigidity and stability – decisive factors for high precision and high productivity. The KELLENBERGER 1000 has hydrostatic guideways in all main axes for the highest form accuracies in grinding tasks with interpolating axes.
The hydrostatic B axis is equipped with a direct drive. The turret grinding head thus swivels about three times faster than without direct drive and positions with an accuracy of less than one angular second. Particularly when machining requires the swiveling-in of different grinding wheels, this reduces non-productive times and thus increases productivity. More than 30 grinding head variants with external and internal grinding spindles allow a wide range of machining options and the right application-specific configuration at all times.
Just the right machine for the high demands at Oerlikon Barmag! Andreas Böttcher is satisfied: “As far as the required parameters are concerned, the old VARIA and Kel-Vera machines are just as precise as the new machine. However, the better accessibility on the new machine facilitates the changeover of parts and also the service, and the improved energy efficiency noticeably reduces costs.”
When asked why Kellenberger is repeatedly awarded the contract as a supplier for grinding machines, Andreas Böttcher replies: “The business relationship has proven itself and strengthened over many years. For us, Kellenberger is not only a machine supplier, but rather a development partner and consultant for manufacturing processes. And it’s like this: of course, the technical and commercial requirements have to be met, but beyond that there are other elements that simply have to be right as well. This includes a good service. Kellenberger machines are – thank goodness – very reliable. But if we do need service, everything is handled in an exemplary manner.