Historically, taconite-type seals derive their name from a type of iron ore mined in Minnesota’s Mesabi Range in the United States. Due to the invasive, highly abrasive nature of this material it would penetrate past seals into bearing housings, causing the bearings to fail very rapidly. To overcome this problem, since the 1960s engineers have been developing “taconite seals” intended to resist the ingress of harsh and abrasive dust in wet environments.
SKF Australia have created a new taconite seal design to improve the sealing performance for split housings to combat abrasive, corrosive and high-pressure wash-down applications. The resulting new seal provides exceptional results in excluding contaminants and provides lower maintenance costs and reduced grease consumption.
The ultimate SKF three-barrier solution
The SKF Taconite Seal forms part of what SKF regards as the three-barrier solution which consists of an SKF housing incorporating SKF Taconite Seals, a grease barrier and an upgraded sealed SKF Explorer spherical roller bearing. This approach is designed to offer the ultimate performance in contaminated and wet situations, particularly where there are likely to be high-pressure wash-downs of equipment.
With this combination, the SKF Taconite Seals is the primary barrier that prevents the entry of dirt and water; a secondary barrier is provided through a grease fill in the housing cavity, and the final barrier is at the upgraded sealed SKF Explorer spherical roller bearing that keeps out contaminants during installation and operation.
Technical features of SKF Taconite Seals
Essentially, the SKF Taconite Seal is a heavy-duty multi-stage axial labyrinth cartridge seal suitable for split bearing housings, comprising two labyrinth rings, one rotating and one stationary, an internal low-friction V-ring and provision for a grease purge. The V-ring seals against the stationary labyrinth ring to provide effective grease purge and to resist the penetration of contaminants into the housing. An O-ring in its bore seals the rotating labyrinth ring to the shaft to prevent water penetration and corrosion.
Grease filling and purging
The SKF Taconite Seal is supplied with a grease fitting for the grease purging of the labyrinth. This purges the labyrinth of contaminants and helps block the entrance of contaminants. In customer field tests in conveyor pulley applications for example, when used with the upgraded sealed SKF Explorer spherical roller bearings, this seal has reduced grease consumption, associated maintenance tasks and costs by up to 60 percent.
Proven performance
Solutions incorporating the SKF Taconite Seal have demonstrated the improved performance of the equipment. One customer approached SKF with an issue related to conveyor pulley bearings mounted in competitor block housings with taconite seals. The conveyor used for loading iron ore onto ships was experiencing pulley bearing failures due to contamination of the lubricant. The mean time between failure (MTBF) for bearings was less than a year due to gross iron contamination of the bearing grease inside the bearing housing. When analysed, it had a content of between 5,000 and 14,000 ppm. When the existing seals were replaced with SKF Taconite Seals, the level of contamination dropped dramatically to only 10 to 60 ppm with bearing life extended by almost four times and beyond the expected life of the pulley lagging, which is more than four years.
In conclusion, the development of the new SKF Taconite Seal when combined with the SKF three-barrier solution brings significant benefits to the processing and mining industries at a global level. It is a standardised design with compact dimensions and easy installation, delivering improved technical features such as superior seal performance and high misalignment capability, while also contributing to lower environmental impact.
For more information email customerservice.nz@skf.com
