Tham khảo tài liệu 'fag_rolling_bearing_lubrication part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Lubricant in Rolling Bearings Functions of the Lubricant in Rolling Bearings Contamination factor V Contamination factor V depends on the bearing cross section the type of contact between the mating surfaces and the cleanliness level of the oil table in fig. 11. If hard particles from a defined size on are cycled in the most heavily stressed contact area of a rolling bearing the resulting indentations in the contact surfaces lead to premature material fatigue. The smaller the contact area the more damaging the effect of a particle of a defined size. At the same contamination level small bearings react therefore more sensitively than larger ones and bearings with point contact ball bearings are more vulnerable than bearings with line contact roller bearings . The necessary oil cleanliness class according to ISO 4406 fig. 12 is an objectively measurable level of the contamination of a lubricant. It is determined by the standardized particle-counting method. The numbers of all particles 5 pm and all particles 15 pm are allocated to a certain oil cleanliness class. An oil cleanliness 15 12 according to ISO 4406 means that between 16000 and 32000 particles 5 pm and between 2000 and 4000 particles 15 pm are present per 100 ml of a fluid. The step from one class to the next is by doubling or halving the particle number. Specially particles with a hardness of 50 HRC reduce the life of rolling bearings. These are particles of hardened steel sand and abrasive particles. Abrasive particles are particularly harmful. If the major part of foreign particles in the oil samples is in the life-reducing hardness range which is the case in many technical applications the cleanliness class determined with a particle counter can be compared directly with the valves of the table on page 46. If however the filtered out contaminants are found after counting to be almost exclusively mineral matter as for example the particularly harmful moulding sand or abrasive grains the measured values .
