In recent years, the papermaking industry has been making great strides by enhancing the speed and the width of coverage of papermaking machines with the objective of boosting productivity. To reduce the amount of downtime caused by unexpected problems, customers demand high reliability from the bearings that are used in papermaking machines. NSK has developed a range of bearings that meet these demands, and the company's bearings are used in all sections of modern papermaking machines. In particular, NSK is supporting papermaking with two kinds of bearings:
- TL (tough and long life) bearings designed specifically for dryers. These were developed by taking full advantage of the company's material heat treatment technologies
- NSKHPS™ High Performance Standard Bearings for Industrial Machinery Spherical Roller Bearings developed by integrating NSK's materials, design and manufacturing technologies.
NSK will continue to develop highly reliable bearings that will lead to further productivity improvements in the papermaking industry, and it will continue to contribute to the development of the industry.
NSK Experience & Technology
The bearings that are used in the dryer rolls of papermaking machines operate in hot environments because high temperature steam is passed through the rolls. The following are examples of the kinds of bearing damage that can consequently arise:
- early abrasion caused by insufficient formation of a film of lubricating oil
- creep from bearing variance caused by use at high temperatures over long period
- fracture of the inner ring in the bearing from an increase in fitting stress as a result of temperature differences between the shaft and the ring.
In particular, fracture of the inner ring (3, above) in the bearing can constitute a serious incident that results in production stoppages. In response, NSK has developed its TL (tough and long life) bearings. Thanks to the use of a special nitrocarburizing treatment for the materials, the fracture strength of the inner ring has been increased and dimensional stability at high temperatures is excellent.
These TL bearings have the overwhelming trust of the market, and they enjoy an unassailable position as the leading choice for dryer cylinder roll bearings.
TL Series Spherical Roller Bearings
Provide superior resistance to inner ring fractures, which is ideal for papermaking machinery operating under high-temperature conditions. The tough, long-life, TL series of bearings help boost productivity and lower costs.
- Adopting NSK's proprietary steel grade (new specification bearing material) and a special case hardening and heat treatment process, resistance against inner ring fracturing has been dramatically improved.
- Raceway surface hardness has been increased for longer life performance.
- Dimensional stability under high temperature (200℃) operating conditions.
NSK successfully developed the NSKHPS series of spherical roller bearings, which provide a longer service life and higher limiting speeds, by employing leading-edge materials and technology in combination with years of cultivated experience and technical know-how.
- Bearing life increased by twofold (increased dynamic load rating by 25 %).
- Limiting speed increased by 20 %.
Molded-Oil bearings are lubricated with oil-impregnated solid material, which is contained within the bearing. Oil slowly seeping from this solid lubricant material provides ample lubrication to the bearing for extended periods.
- Designed to prevent water and other liquids from washing out the lubricating oil while preventing dust and other contaminants from getting inside the bearing.
- Low-torque performance, which is achieved by packing the bearing with oil-impregnated solid material after bearing surfaces have undergone a special surface treatment.
- Protect the working environment by eliminating stray oil mist or leakage.
- High-speed capability enabled through optimal composition of the solid lubricant material and methods used for the molding process.
By applying NSK's innovative concepts, the EM series bearing has a greater number of larger rollers than that of a conventional bearing. Furthermore, the optimally designed one-piece cage offers high rigidity and low-wear performance.
- Bearing life increased by nearly twofold.
- Noise and vibration levels reduced by 40 to 50 percent.
- Cage strength dramatically enhanced.
A uniquely structured, highly precise, long life, anti-creep bearing that also facilitates easy of handling and mounting.
- High load capacity design
- Vacuum melted, carburized steel for long life performance
- High precision
- Optimal inner ring design for improved lubrication
- Lubrication hole and groove provided on inner and outer rings
The CA series features a machined cage; offers superior radial load capacity and alignment; and provides high load capacity and excellent strength. This product line includes the high-precision products shown on page 55.
- High load capacity
- High-strength machined brass cage