Page 10 of catalogue Super Precision Bearings of Schaeffler Technologies GmbH & Co. KG

Product features of FAG Super precision bearings
FAG accuracy to P4S · The right material · Lubrication

FAG accuracy to P4S
At first glance, the accuracy of bearings seems to be sufficiently defined in DIN/ISO or ABEC standards. Yet FAG Super Precision Bearings go beyond this. In addition to demanding tolerances to P4 or better, there are other performance features that are not covered by these norms. All important product features of FAG Super Precision Bearings meet Precision Class P2. This applies to the running accuracy as well as the parallelism of FAG bearings that are manufactured to FAG standard P4S. Maximum precision bearing arrangements can therefore be designed with standard FAG Super Precision Bearings. (see tolerances for Single Row FAG Spindle bearings, Pages 144 ff.)

The right material
FAG Super Precision Bearings are manufactured from high grade materials. High material fatigue life and wear resistance have been achieved using a specific heat treatment, so that the bearings can in many cases be operated with infinite service life. The material Cronidur 30 is particularly important, as it makes a Spindle Bearing into an X-life ultra Bearing. Its unique properties as to fatigue strength and corrosion resistance result in significantly extended service life, higher admissible contact pressure for infinite service life, higher admissible speeds and significantly enhanced lubricant service life. For Spindle Bearings, Hybrid Bearings, i.e. bearings in combination with steel rings and ceramic balls, are

now standard. Ceramic rollers are also used in Cylindrical Roller bearings. Silicon nitride is the ceramic material that combines the typical ceramic properties in the most favorable way. They offer many advantages over steel rolling elements, such as • outstanding tribological behavior in combination of steel and ceramics. The stress on material and Lubricants is significantly reduced in hybrid bearings. • a lower density that reduces centrifugal forces on the rolling elements, improving the bearing’s kinematics • lower coefficient of thermal expansion of the ceramic rolling elements. It has a positive effect on the change in bearing preload in the event of temperature differences during operation. These factors result in significantly extended bearing life. For this reason, hybrid bearings are now frequently used even at lower speeds.

FAG Super Precision Bearings

parts of the process. The result of this extensive process is an approved product specification for the lubricant in question, whose precise compliance is ensured by continuous inspection.

Lubrication
The grease used plays an important role in the overall bearing system. The decision as to grease or oil lubrication has a significant effect on the system costs. The goal of Schaeffler Group is to permit and advance grease lubrication even at maximum speeds. Before a lubricant is approved for bearings, it undergoes a strict approval process. The calculations and suitability tests for the application-specific requirements, for example the temperature behavior and run-in behavior of a spindle running at high speed, are very important

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