Mining and Heavy Industry - H-T-L USA

© 2019 - H-T-L perma USA LP | www.permausa.com | 5 ROLLER BEARING FAILURES Unsuitable lubricant Insufficient lubricant amount Solid contamination Other failure causes Liquid contamination Aged lubricant Bearing damage Over-lubrication Insufficient lubrication Source: Calculation leading bearing manufacturers: Material cost and time, maintenance runs / roller bearing industry To maintain competitiveness, mining and heavy industry operations such as steel mills must maximize production output while minimizing long-term operating costs. A key component to achieve this is the implementation of preventative maintenance strategies which extend equipment service life and minimize the downtime required for maintenance, repair and overhaul. Success in this area reduces the total cost of production assets and ultimately improves business performance. Cost and downtime due to premature wear is significant. For grease lubricated bearings, well considered lubrication strategies have a dramatic effect on extending bearing service life and therefore reducing costs and improving equipment reliability. The chart provides estimates of the causes of premature bearing failures. Major causes are poor lubrication practices and conta- mination. In recognition of this, industry leading businesses invest in automatic lubrication systems for the purpose of bearing relubrication and contaminant exclusion because they deliver superior reliability results compared to manual lubrication. Benefits of short relubrication intervals Introduction Bearing relubrication addresses the need to maintain sufficient fresh grease around the working components of bearings as they rotate. Insufficient or infrequent relubrication leads to deterioration of lubrication conditions, lubricant starvation, and premature wear. Meanwhile, for high speed bearings, the rapid supply of excessive amounts of grease can cause over-lubrication which leads to degradation of grease condition and threatens the service life of bearings. The longest bearing service life is achieved when grease is added in small amounts at short intervals. When implemented correctly, this regime of grease delivery maintains a steady state of lubrication protection where over-lubrication and lubricant starvation do not occur. Factors which reduce the service life of grease include high speeds, elevated operating temperatures, vibration and high loads. When operating conditions such as these prevail, the benefits of delivering small amounts of grease at short time intervals are at their greatest. The diagram to the right demonstrates the differences between re-lubrication methods which deliver small amounts of grease at short intervals and those which deliver large amounts at extended intervals. Too much grease  Potential for elevated operating temperature and rapid degradation of grease for high speed bearings  Less efficient use of fresh grease  Potential to damage contact type seals Too little grease  Starvation causing premature wear  Under-lubrication leads to accelerated degradation of remaining grease  Increased potential for contamination entry due to lack of lubricant purge