Schaffler develops energy-efficient bearings

Schaeffler Group has developed a range of energy-efficient bearings that help reduce the overall energy consumption in power transmission systems and machines.

The deep-groove ball bearings are said to offer 35 per cent less friction and 50 per cent less noise than their predecessor, with the addition of sealing and a riveted steel cage.

The Generation C FAG deep-groove ball bearing achieves high running speeds and efficiencies, while increasing the life of the bearing and reducing energy consumption.

By optimising the raceway curvature between the balls and rings, the bearings produce 35 per cent less friction because they generate less heat, which makes them suitable for higher running speeds.

They are therefore suitable for applications in which low noise and smooth running are important, including electric motors, power tools, ventilators and washing machines.

Schaeffler has also modified the seal on the Generation C bearings.

The HRS seal is made from nitrile butadiene rubber and has modified double-lip geometry.

The seals are adjusted to match the recess on the bearing inner ring, with axial contact between the inner ring and the seal enabling protection against contamination or loss of grease and frictional torque.

This results in longer grease life, increasing the life and reliability of the bearing and provides improved bearing performance at higher speeds.

Venting grooves have also been added in order to improve the run-in behaviour of the bearings.

The bearing shield has also been modified and the recesses on the bearing rings and the shield geometry are functionally adjusted, creating an axial and radial labyrinth with the shield.

The improved guidance of the rolling elements also contributes to higher performance of the bearing.

The riveted steel cage, which replaces the previous steel 'ribbon' cage, offers higher rigidity and so is suitable for higher running speeds.

It also reduces noise levels and means the bearing is less sensitive to shock loads.

The manufacturing tolerance of the bearings has been increased (to P5 Abec 5 standards), with ball roundness to G5 tolerances and improved surface finish.

The 'ball roller' is an energy-efficient range of bearings that utilise spherical bearing elements, but have cut off sides.

The result is a range of ball roller elements that offer all the axial load handling capabilities of fully spherical balls but allow overall bearing width and mass to be decreased by around 20 per cent, as well as reducing friction.

This allows for the carrying of greater loads and a larger grease reservoir or more space for improved sealing.

In the new design, Schaeffler has removed all areas of a conventional rolling element ball that are not under load.

The result is a flattened ball on both sides, which is 30 per cent narrower than a conventional ball, enabling the number of rolling elements to be increased.

This in turn enables the filling capacity of the bearing to be increased by up to 90 per cent.

Using more rolling elements in the same design space results in higher load ratings and longer service life, providing opportunities to downsize products and assemblies.

According to Schaeffler, only 70 per cent of the ball width is utilised in a typical ball bearing, so the outer 15 per cent to the left and right of the ball diameter can be considered redundant.

This discovery led the company to cut off this redundant material from the sides of the balls.

The development team realised that cage design would be critical to the new bearing.

The critical conditions occur during initial rotation.

Once the bearings are moving under conditions of speed and load, they become self-locating, like a bicycle wheel.

In addition, having moved away from a fully spherical shape, it is possible to give the roller a logarithmic profile, since the rotational axis is always perpendicular to the variable contact angle.

The osculation conditions therefore do not change.

If the load ratio changes from axial to radial and the contact angle changes as a result, the osculation 'creeps' in an optimum manner with the change in load.

Schaeffler's standard 6207 ball bearing (DIN 625) incorporates nine rolling elements, which equates to a fill capacity of around 60 per cent.

In comparison, the new BXRE207 ball roller bearing contains 14 rolling elements in the same space.

Here, the filling capacity is increased to 90 per cent and the bearing life is 2.4 times longer.

Schaeffler's single-row BXRE bearing offers higher load carrying capacity than a standard ball bearing in the same design space.

This is due to a 50% increase in the number of rolling elements by using innovative assembly methods.

The resulting filling capacity is around 90 per cent, which means the BXRE bearing can withstand extreme loads.

The bearings are therefore ideal for the downsizing of products and assemblies, as they require less radial space with the same shaft diameter and the same load ratings.

Typical application examples are electric motors, washing machines, power tools and industrial gearboxes.

The BXRO range of ball-roller bearings are double-row bearings with the rolling elements in an 'O' arrangement, enabling the bearings to support both radial and axial forces.

Compared to Schaeffler's Series 32 ball bearings, up to 50 per cent more rolling elements can be fitted in the ball roller.

The advantage of the BXRO over the 33 Series (which has two inner rings) is in the simplified installation of the inner ring on the shaft.

The optimised raceway geometry of the single-piece inner ring results in increased bearing accuracy.

Applications include automotive manual transmissions and textile machinery.

The BXRT ball-roller series is a double-row design with the rows of ball rollers in a tandem arrangement.

The rolling elements can be guided using one or two cages.

The two-cage design enables the optimal adjustment of the two raceways independently of each other to match the application.

This ensures maximum load support with minimum size and reduced friction.

Compared to tapered roller bearings, friction is reduced by around 30 per cent due to the elimination of rib friction.

This means that energy consumption can be significantly reduced, leading to applications in manual transmissions, differentials, hydraulic motors and pumps.

Schaeffler has also launched a ball-roller bearing for use as a wheel bearing, reducing friction and weight in passenger cars and commercial vehicles.

The four-row, BXR4 wheel bearings offer higher load-carrying capacity and therefore enable more compact designs than conventional wheel bearings.

The bearings are suitable for driven axles.

Reduced friction and reduced weight of the bearing and wheel carrier contribute to reduced fuel consumption and exhaust emissions.

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