Industrial gearboxes are used in many different sectors and often face dynamic operating conditions twinned with high shock loads in some cases. They are usually located between the drive on one side and the process technology on the other. In this case, industrial gearboxes primarily serve to reduce input speeds and increase torques for the processes in question. Typical applications include power generation and mining.
All industrial gearboxes have to function reliably in spite of the dynamic processes acting on them. As higher-performance machines keep emerging, the bearings used for shafts also play a crucial role in ensuring reliability in service. These are also tailored specifically to the relevant application.
For instance, NSK supplies solutions for every stage of the planetary gears used for wind turbines, from the planetary carrier to the generator shaft. Various options are available: traditional locating/non-locating bearings, floating bearings and adjusted bearing arrangements. The choice of material is another key consideration. NSK’s Super-TF technology maximises bearings’ service life, even in operating conditions where conventional bearings would show signs of fatigue damage. If it is also possible to change operating conditions for the better, the components can last several times longer than standard bearings.
Two key innovations extend the lives of heavy-duty cylindrical roller bearings by up to 30%. Firstly, an increase in the number of rollers reduces the surface pressure on the contact area between the rollers and the raceway, thereby increasing the maximum load. Secondly, an optimised cage provides sufficient stability despite the larger number of rolling elements.
Electric motors and generators place completely different demands on bearings compared to gears. Knocks and fluctuating torques rarely occur. Different speeds are usually the key consideration when it comes to selecting bearings.
Performance classes vary, however. Electric motors and generators in the consumer segment – such as drive motors for washing machines or car alternators – usually have to fit in a very small space and tend to operate under constant conditions. Motors and generators with a higher power density are normally used in industrial plants or to produce power, where considerable load variations are commonplace.
In electric motors and generators, the shaft bearing often has to be insulated from the housing to prevent damage caused by current conduction. With this in mind, NSK has developed electrically insulated bearings with a ceramic coating which are suitable for the conditions associated with these specific mechatronic applications.
NSK can supply the right bearings for all operating conditions and applications, such as extremely compact deep-groove ball bearings which deliver ultra-quiet running along with optimised low energy consumption and require no maintenance.
Some applications are prone to causing bearing damage and premature failure due to electrical corrosion. Electrical corrosion is damage to the raceway resulting from electrical discharges between the rolling elements and the raceway. With its electrically insulated bearings, NSK offers a special product with high insulation resistance to deal with this problem. The bearings’ rings are coated with a layer of ceramic which has a set thickness. This is applied using a special spraying technique designed to ensure that the coating bonds securely to the bearing steel.
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