Not just good on paper: A proven track record for Dryer Roll Bearings

Jun 28, 2023

Manufacturers’ Monthly finds out how installing NSK's TL Series Spherical Roller Bearings has helped a major paper mill solve problems with its production process.

Paper is a valuable resource in many aspects of day-to-day life. From printing and packaging to mail, publishing, and documentation, its production generates thousands of jobs, predominantly in rural and regional areas of Australia. In addition to pulp and paper mills, recovery and recycling operations serve to create a circular and more sustainable industry, with flow-on effects for forestry and manufacturing sectors.

Within a standard paper making machine, dryer cylinders work to remove any remaining water from the paper, after it has gone through vacuum and pressing stages. They also encourage the fibres to bond together using a controlled heat transfer process. The steam-heated cylinder rolls, make up the largest part of the overall machine, and are usually grouped in sections that are each operated by an independent drive.

Many years ago, when a large paper mill in Victoria began experiencing issues with their dryer cylinder bearings, Motion Australia representative Mark Bristowe collaborated with NSK to develop an effective alternative that would prove long-term. After installing the TL Series Spherical Roller Bearings, the site began experiencing much longer change-out intervals and fewer machinery breakdowns.

"This customer sources a range of critical parts through Motion Australia, and the TL Series Spherical Roller Bearing is one that they have been using successfully now for a long time," said Bristowe, who manages Motion Australia's BSC Sunshine branch. "I worked in conjunction with NSK to implement this solution, which has eventuated in lower maintenance costs and increased equipment reliability on the plant."

According to Nitin Verma, Business Development Manager at NSK, inner ring cracking in spherical roller bearings used in dryer cylinder rolls is a common issue in paper machines due to high temperature variations within the bearing. For this reason, NSK developed the TL Series as a purpose-built bearing for the papermaking industry.

As Verma explained, "the steam flowing through the dryer cylinder rolls creates a temperature differential within inner ring and the shaft which creates excess hoop stress in the inner ring leading to its cracking. NSK's TL carburised steel is capable of handling increased hoop stress compared to standard bearing steel countering the inner ring cracking issue."

Verma elaborated that this customer now has the TL Spherical Roller Bearings in service across five of their high-volume paper machines. On each machine, there are multiple sets of dryer cylindrical rolls which slowly heat the paper ‘web’ before feeding it through to be trimmed and finished.

Designed to deliver on high performance expectations despite extreme temperature conditions, the TL (‘Tough and Long-life’) Spherical Roller Bearings ensure dimensional stability of the bearing up to 2000 C. This is achieved by doing special heat treatment on patented carburised bearing steel which also allows higher wear resistance enabling longer life in tough operating conditions.

As part of the broader Tough Technology range, this NSK innovation serves to address an industry-specific problem commonly seen on papermaking machinery. According to Mark Bristowe, being able to identify the root cause of these vulnerabilities and apply extensive industry knowledge is where the collaboration between Motion Australia and NSK shines through.

"We have had an excellent relationship with NSK over the years and working alongside Nitin to service this customer has been very successful," he reflected. "He has a great relationship with their engineers, and on the rare occasion when something faults prematurely, he will carry out analysis and offer solutions."

"Because of the ongoing communication between our two businesses, customers can get answers to their engineering concerns, and quickly implemented solutions. Our product experts are well versed to address similar issues in a broad range of industries."