SKF AB (Sweden) announced that the company's Hammer Seal Lip (HSL) seal design is now being standardized across a wide range of the world's most popular deep groove ball bearing sizes.
The HSL was originally developed in 1998 to meet the escalating needs of specific power tool and automotive alternator applications. By applying this premium seal technology to its most price-competitive bearings, SKF is positioning them further away from the commodity side of the industry.
The key design parameter, according to SKF, was the ability of the new seal design to survive linear speeds of 27 meters/second (18,000 RPM) -- standard design speeds are normally 15 meters/second. Another important design criteria was the ability of the seal design to continue functioning well at those speeds and while experiencing radial and axial loads. Sealing efficiency over a wide temperature range had to be achieved, both against contaminants and to keep the lubricant inside the bearing.
SKF's Netherlands Engineering & Research Centre handled the seal design and optimization, using customized finite element analysis software.
The resulting Hammer Seal Lip seal is named for the claw hammer cross-sectional shape of the seal lip where it rides on the inner race. The seal has a long, thin, radial, flexible lip that rides on a special seal groove machined into the inner race. The groove keeps out contaminants, while the internal shape acts as a labyrinth to allow proper grease flow and retention.
Polyacrylic rubber was specified for its ability to withstand high temperatures while resisting lip tearing.
The HSL's success in those most demanding applications has now led to it being standardized across almost all of the company's small deep groove ball bearings.
Two designs are being used. The new RSL (Light contact) design replaces the old RZ seal. The new RSH (Hard contact) design replaces the old RS1 seal and is patented in several countries. There are no changes in nomenclature or bearings using shields.
For example, a 6203-RSL would have a single RSL seal on one side, while a 6203-2RSL would have RSL seals on both sides.
Initially, only 60, 62, and 63 series ball bearings will be equipped with HSL seals. in four different designs:
RSL 6mm through 9mm ID and up to 52mm OD
RSL 10mm through 25mm ID and up to 52mm OD
RSH 6mm through 9mm ID and up to 52mm OD
RSH 10mm through 25mm ID and up to 52mm OD