By Lily Bearings
©2004-2008
The Schaeffler Group uses modern coating technology in order to optimize the functionality of surfaces in heavily loaded rolling bearings and precision components. In focus are coatings that prevent or reduce corrosion and fretting corrosion, as well as wear, friction, slippage and the passage of current. Offered under the trademarks of Corrotect®, Durotect®, Triondur® and Isotect®, the coatings are applied to the component surfaces in a number of different methods, without a thermo-chemical diffusion occurring between the coating and the base material.
For many years now, the Schaeffler Group has been spearheading the field of surface and coating technology. The importance of this technology will continue to increase, especially due to growing product requirements in the industrial and automotive engineering sectors. The Group¡¯s Surface Technology Center provides development engineers at Schaeffler with facilities and capacities, which open up new possibilities, in particular when it comes to combining different processes and materials. Here it is crucial to consider the overall system requirements placed on the specific rolling bearing. Moreover, the surface as a design element should be integrated in the development and product evolution process at an early stage. The Schaeffler Group¡¯s Surface Technology Center enables both development work on a laboratory scale and its successful transfer to large-volume production processes.
Tribological coating systems ¨C in other words, coating systems that are friction-optimized and wear-resistant ¨C can be developed and implemented with the help of a PVD/PACVD development facility. The coating material is either in the form of a solid (PVD ¨C Physical Vapor Deposition) or in the form of a gas (PACVD ¨C Plasma Assisted Chemical Vapor Deposition) and is vaporized in a vacuum. In contrast to conventional coating methods, this environmentally friendly vacuum process enables unique compositions of different materials and coatings to be achieved.
One example is Triondur® C coating. Developed especially for rolling bearing applications, this carbon-based adamantine coating system offers an extremely high level of protection against abrasive and adhesive wear, whilst reducing friction to a minimum. Dry friction against steel is up to 80 percent lower. Even if only one friction surface is coated, the operating life of the entire tribological system is increased significantly. Due to its highly ductile coating structure, Triondur® C can withstand the high contact pressures that occur in rolling bearings. Typical applications include barrel rollers in spherical roller bearings for paper calenders, barrel rollers in axial spherical roller bearings for hydraulic motors and track rollers with coated outside diameters used in the printing industry.
There is also an electroplating facility that is used for developing environmentally acceptable and therefore customer and future-oriented anti-corrosion coatings. Part of the focus is now on developing coatings that are free from hexavalent chromium (Cr-VI) and comply with the stringent requirements of the new EU End-of-Life Vehicle Directive. Both development facilities also enable cost and function-oriented combinations of different vapor deposition methods and coating systems. This supports the build-up of comprehensive surface technology competence within the Schaeffler Group.
In conjunction with Schaeffler¡¯s central R&D facilities where employees in the testing, basic research and calculation departments, together with the materials scientists provide comprehensive knowhow, the Surface Technology Center is synonymous with the rapid implementation of tailor-made, customer-oriented surface engineering solutions.