Production rate and operating expenses (OPEX) highly depend on proper maintenance to ensure reliable operating equipment. At pellet plants, bearings are a key replacement part in chains, conveyors, moving floors, ventilators, hammer mills, pellet mills and many other devices. &nbsp;The following are some of the top reasons for bearing failure at pellet operations.Lack of Lubrication and Contamination&nbsp; When bearings spin under high loads with inadequate lubrication, they may experience metal-to-metal contact. This results in increased wear, overheating and potential contamination of the lubricant. To prevent this, it is crucial to check that the right type and amount of lubricant is being used, and that it is being reapplied at the correct intervals. If contamination is detected, it is important to inspect the seals. In some cases, using a thicker lubricant may help, and in many cases, greases with solid particles are superior, as the particles act as an additional sealant. It is important to note that over-lubrication can also cause problems.Electric Erosion&nbsp; Electric erosion, which is caused by the electric current that passes through bearings, can lead to micropitting and failure. It is difficult to prevent electric discharges that damage the surface of bearings. Electric motors charge nearby bearings by emitting current. Most greases have a moderate to fair insulating character, but using high-insulation grease can help prevent electric discharge damage. However, the increased insulation can cause higher charges that discharge with much stronger force, causing more severe damage if the insulation is not sufficient. Other options include using insulated bearings and insulated couplings. Although these solutions are effective, they are also more expensive than shaft grounding.Vibration&nbsp; Bearings can be damaged by vibration during transportation or during storage before installation. This can cause false brinelling, which appears as marks in the bearing races. In pellet plants, this type of damage can happen when third parties refurbish rollers and other equipment outside of the facility. To prevent damage during transportation, it is important to secure the shaft axially and radially with a flat piece of steel and a strap, respectively. During storage, the shaft can be turned regularly to spread out any vibrational contact across the bearing surface. Pre-lubricating the bearings and additional no-load run-in procedures can also reduce possible damages from transport and storage.Improper Installation and Setup&nbsp; Improper installation and setup can cause various types of damage, such as true brinelling, misalignment, imbalance, excessive belt tension and mounting errors, leading to overloading. To avoid these issues, it is important to follow the recommended installation procedures and use quality instruments to check alignment, tension and other factors. Original equipment manufacturers and third parties offer staff training and share best practices.Insufficient Loads and Overload&nbsp; Bearings require a minimum load to function properly—an inadequate load can be just as damaging as excessive load. Damage from insufficient load appears as smearing on the rolling elements and races. This is especially important to keep in mind when using cylindrical roller bearings, which are designed for larger loads, and does not apply to preloaded bearings. Overload, on the other hand, results in deformations similar to shock loads or improper handling.Especially excessive, abrasive wear occurs with inadequate lubrication, wrong volumes or insufficient quality. High-performance lubricants with a higher number of additives are able to cope with the demanding environments in a pellet plant and help improve the lifetime of bearings. When aiming for lower OPEX, a closer examination of the lubrication program is required.Conclusion&nbsp; In summary, addressing the underlying principles of bearing failure in pellet plants necessitates a multifaceted approach that encompasses lubrication management, electrical protection, vibration mitigation, installation excellence and load optimization. By implementing proactive maintenance strategies informed by advanced technologies, as well as fostering a culture of continuous improvement, organizations can enhance equipment reliability, minimize downtime and maximize operational efficiency in pellet plant operations.Author:&nbsp; Holger Streetz&nbsp;&nbsp; COO, Bathan AG&nbsp;&nbsp; h.streetz@bathan.ch

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Bearings are a key replacement part in many pellet plant components. 

Bearing Failure at Pellet Plants: Top Causes

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Bearing Failure at Pellet Plants: Top Causes