Each year , approximately 20 sets of bearings had to be replaced due to failures every 4 to 6 weeks . After analysis by NSK , it emerged that the primary cause was water and dust infiltrating the bearings . NSK therefore recommended replacement with Molded-Oil bearings . A test was run and the operating life of the bearings increased to 26 weeks . This significantly boosted the productivity of the manufacturing line , helping the user to save approximately € 9,400 annually in maintenance and downtime costs .
In a final example , a vegetable processing company had installed a biogas plant in order to ferment organic waste from production and transform the resulting methane into electricity and heat for selfconsumption . However , problems had been found with the rotary screen , which filters-out coarse and non-fermenting material prior to the fermentation stage . Failures were occurring repeatedly in the bearings of the rotary screen and disrupting the overall operation of the
biogas plant . Every six weeks on average , the deep groove ball bearings with contact seals had to be replaced . Each rotor has two bearings and there are two rotors per rotary screen . Replacement time was one hour each .
Experts from NSK found that the breakdowns were caused by contamination penetrating the bearing raceways . The customer subsequently followed NSK ’ s recommendation to install Molded-Oil deep groove ball bearings made of stainless steel with DU seals on both sides , a move that has led to far fewer replacements .
This yet again confirms one of NSK ’ s “ rules of thumb ”: in applications where the environment is contaminated by moisture and dust , the service life of Molded-Oil bearings in stainless steel is more than twice that of bearings with conventional grease lubrication .
pilath-m @ nsk . com www . nsk . com
36 FDPP - www . fdpp . co . uk