NSK has developed super precision bearings equipped with next generation polymer cages that help improve the quality of machine tools. These include the TYN cage, which offers silent operation and 20% lower temperature generation in angular contact bearings used in machining centers and grinding spindle applications; and the TB cage for double row cylindrical roller bearings. Designed using FEM analysis, the TB cage offers similar or superior high-speed performance to brass cages, together with up to 40% lower heat generation, and as much as 10 times improvement in durability when operating under severe conditions.
NSK´s development of the TYN cage is the result of research that shows that silent operation is one of the key features for high-quality machine tools, in order to improve their performance. The TYN cage is made of high-performance engineered polymer, and has a unique design that overcomes the problems of noise sometimes experienced with precision angular contact bearings using conventional phenolic cages and grease lubrication. The NSK TYN cage can eliminate this kind of noise; in particular, it gives greater benefit in machining centers or grinding spindle applications, which require silent operation as specified by builders of high quality machine tools.
The NSK TYN cage provides not only silent operation, but also up to 20% lower heat generation and improvements in the reliability of the lubrication performance. These improvements are achieved by shortening of the running-in procedure, and by ensuring that grease is retained effectively within the bearing.
The NSK TYN cage is available for use in both the Standard ACBB bearings and the ROBUST series of bearings, which are designed for use in high-speed spindles (e.g. up to 16,000 rpm on 70 mm spindle shaft diameter), this type is designed to contribute significantly to the higher accuracy of spindles. It will be stocked as a universal combination (SU) with P3 accuracy (running accuracy: ISO class 2 and dimensional accuracy ISO class 4).
Also new to NSK´s next-generation of high performance polymer cages is the TB cage for double row Cylindrical Roller Bearings (CRB´s). In contrast to conventional CRB, which generally have brass cages- and can suffer grease degradation from wear particles, the TB cage is produced from PPS polymer (Polyphenylene Sulphide) - a type of ´super engineered´ polymer. NSK has developed and refined this new material, PPS, in order to satisfy technical requirements such as extended higher speed capability, and higher levels of durability.
NSK has also conducted extensive FEM analysis to determine the best shape and design of the TB cage under high-speed operation. As a result, the TB cage provides similar or superior high-speed performance, compared to brass cages, together with up to 40% of lower heat generation; and as much as 10 times improvement in durability when operating under severe conditions.
What all these performance improvements mean for the machine tool builder is that a CRB equipped with a TB cage can be operated in a similar speed range to angular contact ball bearings: this was not possible in the past. In addition, it is now possible to operate the spindle and achieve both high-speed performance and greater stiffness characteristics from the combination of CRB with the TB cage.
The NSK CRB bearing specification contains high-accuracy 1:12 tapered bore, oil holes on outer ring, ISO class 4 accuracy and newly defined internal clearance which has a narrower tolerance range to improve the spindle assembling process.
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