Bearings for Wind Turbines: Quality Standards Enable Parts to be Traced

The bearings which NSK develops and produces for the wind power industry undergo special quality checks. In addition to this, they are subject to a specially defined documentation standard, which enables the production parameters for every individual component to be traced even years after it has left the factory.

The code U 303 in the article number of an NSK bearing shows that it was specially developed and produced for use in wind power technology. These wind turbine bearings are made from premium, high-purity bearing steels and special steels used exclusively by NSK. They are also assembled in separate production areas and subject to special packaging regulations, which prevent contamination. 

In addition, NSK’s standard of quality includes a documentation process, which enables each individual component to be traced precisely throughout the production process. Each and every bearing manufactured in line with the U 303 standard is marked with its own product number, which shows the month and year in which it was made. A series of numbers is also allocated to each month so that NSK can see which production batch the bearing belonged to.

This system of individual numbering only makes sense because comprehensive documentation is produced for each bearing that complies with the U 303 standard. All the product characteristics relevant to quality are recorded in these logs. These include, for example, the complete results of materials testing, the parameters of the heat treatment process, the results of all quality checks during the various production stages, and the outcome of the final inspection.

It goes without saying that this documentation system cannot improve the quality of NSK’s bearings for the wind power industry – it can only record it. In other words, the quality of the actual products is more important than the U 303 standard itself, and NSK has very extensive expertise in this field. The company’s know-how ranges all the way from selecting and constantly optimising the high-performance steels it uses – which is one of NSK’s key competencies – to the specific grinding and finishing processes that are employed for bearings destined for the wind power industry.

In recent years, NSK’s research and development department has also made a great deal of progress on optimising its bearing design to cater for the incredibly demanding requirements of wind turbines, both onshore and offshore. As a result of this work, leading wind turbine manufacturers and component manufacturers (generator gearbox and generator)  use various bearing types produced by NSK, all of which meet the U 303 standard. These bearings achieve extremely long service lives, despite being subject to very adverse operating conditions and high dynamic loads.