Mining and Heavy Industry - H-T-L USA

© 2019 - H-T-L perma USA LP | www.permausa.com | 7 When solid or liquid contaminants enter a bearing they cause accelerated wear and the early onset of fatigue. For solid contaminants the rate of wear increases with the size, concentration and hardness of contaminants. Smaller particles lead to abrasive wear while larger particles can cause indentation of bearing raceways which later become sources of surface-initiated fatigue. Greasing practices which prevent the ingress of contaminants provide long-term financial return by means of longer bearing service life and reduced downtime. Strategies for preventing contamination vary depending on bearing housing and seal configurations. For bearings with free-purging labyrinth or taconite seals, contamination prevention is achieved by delivering a consistent purge of clean grease through the seals. In simple terms, if clean grease is purging out of the seal, contaminants (solid or liquid) cannot enter the bearing. Bearings which operate in harsh environments, including high humidity and high levels of liquid or particulate contaminants, demand the strictest attention to regular seal purging. Under such conditions, automated purging of seals provides the greatest benefits. Preventing contamination in harsh operating environments Strategies for the prevention of bearing contamination Strategy 1 – Slurry pump seal purging Automated purging of labyrinth seals provides constant protection against ingress of solids and liquids. For pumps where the wet-end seal is subjected to water spray, a higher rate of automated purging is commonly applied to compensate for the elevated rate of grease washout. Strategy 2 – Conveyor pulley bearing relubrication & seal purging Automated lubrication provides constant protection against the ingress of contaminants. In the example shown, bearing relubrication and seal purging is provided by a single automatic lubrication system. Strategy 3 – Conveyor pulley bearing seal purging (hybrid solution) Automated purging of taconite or labyrinth seals provides constant protection against the ingress of contaminants. For the hybrid solution, bearing relubrication is provided manually on a periodic maintenance cycle. The hybrid system can provide a practical balance between automated and manual greasing for large pulley bearings.