Special bearing designs make cost and performance difference

Citation

(2004), "Special bearing designs make cost and performance difference", Aircraft Engineering and Aerospace Technology, Vol. 76 No. 6. https://doi.org/10.1108/aeat.2004.12776faf.007

Special bearing designs make cost and performance difference

Special bearing designs make cost and performance difference

Keywords: Manufacturing industries, Cost reduction, Bearings technology

The pressure to reduce costs in all areas of manufacturing means that the integration of bearing systems into mating components is proceeding apace. The resulting assemblies are neater, quicker to put together and offer the additional benefits of reducing space and mass and also problems of tolerance stack-up. The designs of bearings used in these integrated assemblies are in many cases special, calling upon manufacturers to provide the highest levels of innovation and manufacturing excellence in supplying bespoke solutions to what are (often) some of the most arduous operating conditions encountered by any equipment type.

Barden is at the forefront of this design transformation, producing both stand alone and integrated special bearing designs, that improve performance and life in numerous areas including aerospace and navigation. The core of Barden's design for products in these areas is the close integration of new materials, surface engineering, lubrication and sealing technologies.

In the area of materials technology Barden's new X-Life ring material has been used successfully in aerospace and non-aerospace applications, reportedly combining superior corrosion and wear resistance with the ability to withstand higher dynamic loads than conventional bearing steels. In addition, when used in conjunction with ceramic balls, significant gains in bearing life and performance are said to be achieved.

In addition to new materials developments, Barden has made significant advances in surface engineering technology. The role of surface engineering in rolling bearing technology is becoming increasingly important as bearings get progressively smaller, but are still required to run faster, carry higher loads and operate reliably for longer periods.

In this field Barden works together with recognised leaders to provide advanced coatings and surface treatments to combat friction, prevent corrosion and reduce wear, even under the harshest operating conditions. The resulting benefits are improved performance, lower running costs and longer service intervals.

Lubrication also plays a major role in any special bearing design, recent developments by Barden being concentrated upon extending the speed and temperature capabilities of greases to enable the replacement of oil in high speed applications. This is important as removal of oil lubricating systems reduces component count, assembly time and overall system cost. In addition, grease lubrication also meets the demands of many sectors of modern manufacturing for sealed for-life operation.

Barden's development efforts with greases have resulted in the introduction of Arcanol L75, a new generation high-speed grease. Arcanol L75 is a Polyurea-based grease that is reported to provide the overall performance improvements necessary to allow costly and complicated oil lubrication systems to be replaced with grease. It has been developed for lifetime lubrication of sealed super precision ball bearings at high speeds: 1.4 ndm for steel balls or 2.0 ndm for hybrids. The grease is also said to excel for its non-critical run-in behaviour, high temperature stability, non-toxicity and favourable viscosity-temperature behaviour.

The increasing use of grease in Barden's special bearing designs has, in turn, resulted in the development of a new generation of seals, both to retain the lubrication medium and to deny the ingress of contaminants. Barden is at the forefront of seal design, as evidenced by a recent success in developing a solution to the previously intractable problem of providing seals in standard angular contact bearings.

Barden claims to have solved this problem with its RSD seal, a unit that enables pump manufacturers and machine tool spindle builders to enjoy the cost, life and maintenance-free benefits of grease lubrication, while enjoying complete bearing interchangability.

The RSD seals have retention characteristics equal to standard seal designs, but are fitted in such a way that there is no contact with the bearing inner rings. As a result, friction is minimised and there is no rise in the bearing operating temperature. The Barden design also overcomes problems of ring distortion from seal radial pressure. And it provides additional operational benefits as the space between seals and balls serves as a grease reservoir.

Barden's special design capability is much in evidence in aerospace markets. The designs vary but have one thing in common, Super Precision ABEC 7/ISO P4 tolerances, as a result they claim to provide high speed operation with excellent levels of reliability, quiet running and minimum power losses. A number of different design configurations are available for use in electric starters and generators, gearboxes, main engines and a variety of auxiliary aircraft functions.

Bearing designs for these equipment areas range from standard deep groove ball bearings to intricate split inner ring designs that are manufactured from high temperature, high strength bearing steels and can accept reversing thrust and combination loads.

Whilst the demands upon Barden's special aerospace designs are great they are equalled, and, in some cases, exceeded by the demands placed on special X-ray tube bearing designs. These bearings are used to support the spinning X-ray anode, operating at speeds in excess of 10,000 rpm under harsh conditions. In addition to withstanding the passage of high voltage, the bearings must also operate in a vacuum environment down to 10-8 torr and at temperatures of 400-500° C.

Details available from: The Barden Corporation. Tel: +44 (0) 1752 735555; E-mail: tmorris@barden.co.uk