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Emerald Group Publishing Limited
Copyright © 2001, MCB UP Limited
Keywords Barden Corporation, FAG/Barden, Bearings, Lubrication
It is reported that the innovative design of FAG/Barden's new DL range enables oil to be taken directly onto the rolling contact surfaces of the spindle bearings, optimising their performance and allowing higher speeds up to 2.8 x 106mm/min to be achieved. The new design also employs precision "O" rings to concentrate the lubricant into the critical bearing areas. This helps to control the problem of excess lubrication, and to reduce the design and manufacturing costs of spindle bearing housings.
The DL (direct lube) bearings (Plate 2) are thought to be a breakthrough design aimed at the highest speed applications – typically machine tools spindles, but also aerospace applications. In aerospace applications the designer is now said to have the option of a direct oil system of lubrication that will provide the bearings with the right amount of lubricant immediately where it is needed – at the rolling elements.
Plate 2 Innovative design DL bearings prove that direct lube is best in high speed bearing applications
For these lubricating systems Barden/FAG will help customers determine accurately the correct dosage level of oil to reduce the risk of excessive friction. For some applications the oil supply can be accomplished axially (i.e. from the side) as well as radially through holes in the outer ring.
Although the decision in the first instance, to use either axial or radial lubrication, depends on the surrounding structure, the use of radially lubricated DL spindle bearings claims the advantage, in most cases, of reducing the costs for the spindle design as a whole. Added to this is said to be the advantage of a more reliable and direct oil supply than is the case with an axial lubricant supply.
The innovative design of the DL bearings has been made possible by FAG/Barden's advanced manufacturing technology. This enables holes of less than 1mm diameter to be machined into the hardened outer ring of the DL bearings, away from the ball to raceway contact zone.
Similar manufacturing technology also provides an oil distribution groove in the bearing outer ring. This groove is one part of a novel design feature that concentrates oil within the bearing. On both sides of the distribution groove are machined highly accurate "O" ring grooves. These accommodate precision "O" rings that reportedly prevent leakage losses and ensure that the right quantities of oil get safely into the bearing. According to Barden, the effectiveness of this design has been proven in extensive tests where forced ventilation was applied to the bearings from every direction without any negative effective on the bearing speed.
Apart from its efficiency of heat reduction and speed, the other major advantage claimed of this design is that, with the "O" ring grooves in the bearing outer ring, there is no requirement for the machine builder to machine grooves into his bearing housing. Consequently, both the time taken for housing design and manufacturing costs are reduced.
Further details are available from Barden Corporation (UK) Ltd. Tel: +44 (0)1752 735555; Fax: +44 (0)1752 733481.