Sleeve Bearing Design for Slow Speed Applications in Cement Plants

Electric motor drives variety of applications in a cement manufacturing plant such as kilns, crushers, ID fans, separators, cooler fans etc. Motor manufacturers serving cement industry needs are often faced with challenging tasks of designing motors suitable for various operating conditions and requirements which are not only reliable but also cost competitive. Some of the drives such as a fan ID drive may be required to operate at speed as low as 50 rpm during turning gear applications which may last up to several hours. Sleeve bearing electric motors operating at low speed such as during turning gear operation require careful attention on bearing design for reliable operations. Safe operation of oil ring lubricated sleeve bearings rely on a generation of hydrodynamic oil film which separates motor rotor and bearing and prevent metal to metal contact. Inadequate development of oil film thickness or boundary lubrication may lead to metal to metal contact between rotor and bearing which can cause bearings to rapidly wear and fail. Although the cost of bearings is a small part of the motor, its failure may cause costly equipment damage and expensive downtime. This paper will discuss some of the key aspects of sleeve bearing design for low speed applications and field practices to avoid bearing failures.