BEARINGS


MOUNTING PRESSURE: installing bearings correctly


Mark Townsend, service engineering manager at SKF, outlines the key


principles of mounting bearings correctly and how digital technology can make the job easier


T


he way in which bearings are mounted has a profound effect on the in-service performance and reliability of these


vitally important parts, but mounting processes are often far from straightforward, requiring an engineer with skill and extensive technical know-how. Bearings rarely if ever fail, but when they do,


the associated unplanned downtime can create significant – and expensive – headaches. Fatigue and improper lubrication are the principal causes of failure in bearings, but their improper handling and mounting are also major, and entirely avoidable, culprits. So, what are the major pitfalls associated with this work and how can they be avoided?


The six ‘Ps’


As the old military adage goes, proper planning and preparation prevents poor performance, and this is especially true when it comes to the handling and mounting of bearings. Before any work begins, drawings and/or instructions need to be studied to determine: • the correct order in which the various


parts of the bearing should be assembled; • the type, size and variant of the bearing to


be installed; • the right lubricant and the quantity in


which it should be applied, and; • the correct mounting method. At this point, the right tools for the job


should also be identified and sourced. Gloves will be needed, as will tools designed specifically for the lifting, carrying and mounting of bearings. While this preparatory work is underway, the


bearings themselves need to be stored carefully in a cool, dry area on shelves that are not subjected to vibrations from nearby machinery and packaging must not be


removed from the bearing until it is time for it to be installed. When mounting work begins, it is critical to


ensure that the bearing, all mating parts and the lubricant are clean and free from contaminants that might cause damage during use. As such, the bearing should be installed in a dry area, away from any potential sources of swarf and dust. If a bearing has to be mounted in a “dirty” environment, steps must be taken to protect it and the mounting position from contaminants until the job is finished. This can be achieved by covering or wrapping the bearing and machine components with plastic or foil. At all times, the bearing must be handled


carefully. Impact damage caused during mounting is a primary cause of early fatigue- related failures in bearings. Should mounting force, for instance, be applied to the wrong ring of the bearing, it can pass through the rolling elements, creating indentations in both the raceways and the rolling elements


themselves, from which further damage can propagate. Further, cylindrical roller bearings can be


damaged easily during assembly. In the case of NU-design bearings, this can happen, for example, after the inner ring is fitted to the shaft and the outer ring with the cage and roller assembly is installed in the housing. If the shaft is askew during assembly and not rotated, the rollers can plough grooves in the raceway of the inner ring. A bearing will only perform satisfactorily if its


associated components are geometrically accurate and if the prescribed tolerances are adhered to. When measuring these, it is important that the components and the measuring instruments are at approximately the same temperature. As a result of all these considerations, there


is much to keep in mind when mounting a bearing. As such, SKF has developed a mobile application to help its customers navigate the intricacies of this work. Called SKF Bearing Assist, the app guides


operatives step-by-step through the entire mounting process. Using the app, the operative first scans the bearing packaging to be mounted. SKF Bearing Assist will then provide all of the information needed by the operative to plan and prepare for the task, listing the tools and parts required, and generating detailed instructions. These procedures can be saved and can be quickly shared with maintenance teams—enabling a more proactive approach to maintenance.


SKF www.skf.co.uk


FEBRUARY 2021 | PROCESS & CONTROL 43


SKF Bearing Assist can even help in the selection of the most


appropriate bearing for a given application and can be used to keep track of bearing exchanges


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