KUSE X-life: A new performance class among linear recirculating ball bearing and guideway assemblies

Schaeffler’s INA linear technology proves with its newly-developed, six-row linear recirculating ball bearing and guideway assembly (KUSE) that significant development advances are possible even for well-established products. KUSE X-life assemblies are highly accurate and run extremely quietly, so that they can even be used in measuring machines.

The infeed zones in linear recirculating ball bearing and guideway assemblies, i.e. the area in which the rolling elements are guided into the load carrying element until the load is fully applied, are critical factors for life-limited components. They ensure that the load is not abruptly applied to the rolling element but gradually. By improving the infeed zone design on the carriage saddle plates, INA Linear Technology has now succeeded in increasing the load ratings for six-row KUSE linear recirculating ball bearing and guideway assemblies by up to 44% depending on the size and design. As a result, the rating life is three times longer than that of conventional designs. Thanks to the significant increase in performance, the redesigned KUSE series has been awarded the Schaeffler X-life quality mark.

Up to 83% less pulse amplitude
Six-row linear recirculating ball bearing and guideway assemblies in X-life quality have a high level of rigidity and extremely low pulse amplitude. They can now also be used in applications that only tolerate slight vibrations and require very high accuracy, such as in measuring machinery. In general, the recirculating rolling elements prevent a constant number of fully-loaded rolling elements being present in the load zone of the carriages. Depending on the effective number of rolling elements in the load zone, the carriage balances deflections along the stroke to varying degrees. This causes a slight, pulsing equalizing movement in the load direction of the carriage. This kind of movement is called stroke pulsation. Pulse amplitudes of up to 1 μm (peak to peak) for a single ball are not uncommon. For the new KUSE X-life guidance systems, the contour of the infeed zone has been optimized in such a way that the stroke pulsation is considerably reduced, especially at higher loads. At a load of 1.35 tons, the pulsation amplitude is less than 0.1 μm, for example. This is a reduction of 83%.

KUSE X-life has the highest rigidity and load carrying capacity based on balls
KUSE X-life linear recirculating ball bearing and guideway assemblies are among the monorail guidance systems with the highest rigidity levels and load carrying capacities based on balls that are currently on the market. Instead of the usual four rows of balls, six rows of balls support the loads: Four rows of balls support loads in a compressive direction with a contact angle of 45°, while two rows of balls support tensile loads. To increase their load carrying capacity, these two rows of balls have a higher contact angle of 60°. Lateral loads are transmitted by three rows of balls. This specific arrangement of ball rows, which is a combination of an X and O arrangement with 45° and 60° contact angles, makes KUSE X-life designs perfect for combined load directions. Compared to four-row linear recirculating ball bearing and guideway assemblies, the combined rigidity can be increased by 15 % on average. In combination with the very low stroke pulsation, KUSE X-life six-row linear recirculating ball bearing and guideway assemblies are particularly suitable for high-precision applications in electronics production, mold production, microscopy, and optics, but also for applications that require a high load carrying capacity and operating performance.