NSK bearings deliver savings to steel plate rolling mill

28 July 2015

NSK (Nippon Seiko Kabushiki Kaisha), a roller bearing specialist and automotive supplier, its bearings has helped a major steel manufacturer’s plate rolling mill achieve €46,000 ($50,819) savings.

Until recently, a daily maintenance routine was required on the rolling mill’s existing open roll bearing to ensure sufficient lubrication, said a statement.

An analysis by NSK, however, led to the proposal for the application specific product replacement, and the subsequent installation of advance Sealed-Clean bearing, which were designed specifically for use in heavily contaminated environments and offers 2.7 times longer life that conventional roll neck bearings, it said.

The iron and steel industry is among the most demanding environments in which power transmission equipment is expected to operate.

The bearings used on rolling mills have to cope with a multitude of extreme operating conditions, which include high temperature variations, both fast and slow rotational speeds, and heavy loads. In addition, they are expected to withstand exposure to moisture, corrosive contaminants and damaging particulates.

At this steel manufacturer, the team of maintenance engineers was having to spend valuable time every day re-lubricating its bearings.

The arrival of the NSK application engineers signalled a change of technology, namely the deployment of a bearing with enhanced sealing protection and better bearing steel technology.

Through NSK´s Added Value Programme - AIP, the additional benefits of the Sealed-Clean range could be ably demonstrated.

The solution centred on the adoption of four-row, sealed tapered roller bearings on the roll necks of the steel manufacturer´s rolling mills.

They are manufactured from the company´s patented Super-TF bearing steel. This innovation was derived from NSK research that set about tackling the problem of bearing life in conditions of contaminated or inadequate lubrication - two major causes of premature bearing failure in rolling mills.

The research revealed that bearing life in such conditions could be improved by altering the bearing steel´s microstructure, thus enhancing its ability to relax stress concentrations on the edges of indentations.

The microstructure, featuring a high quantity of retained austenite and high hardness, will be able to deliver extended life, even where there is an insufficient oil film to protect the bearing´s surfaces from damage.

In reality, the most impressive results are seen when both retained austenite and hardness are increased together, rather than in isolation, as is the case with Super-TF steel, said the statement.

A major feature of NSK´s latest design of Sealed-Clean bearings is the inclusion of the cage flange within the seal space of the bearing, which permits the use of longer rollers.

In addition, the cage diameter is now bigger to accommodate more and larger rollers without any detriment to cage strength.

From a performance perspective, these enhancements will elevate the basic dynamic load rating capacity by up to 34 per cent when compared with NSK's conventional roll neck bearings, it added.