Fundamental to gearboxes, bearings are put to the test in several extremely difficult working practices. As a consequence to varying speeds of operation, serious loads, contaminated lubricants and a little rough territory, the engine is sure to heat up. Bearing manufacturers, however, must meet market demands and supply bearings which can offer great, continuous service from at least 15 to 25 years!
In the field of power transmission applications, NSK is a main source for bearings across the world. Recently, NSK reviewed and assessed many gear designs in present-day use, including spur, worm, epicyclics, hypoid bevel and other bevels. A extensive range of features, such as load, velocities, shaft structures, lubrication, assembly areas and environmental influences were put under scrutiny! In fact, anything that may possibly influence gearbox performance was very carefully examined.
This eventuated in a “solutions based” approach: a method incorporating the latest advances in materials technology, motorized design and software. The solutions-based technology package brings together a spherical roller bearing with a distinctive bearing material, Super-TF, which in the existence of contaminated lubricant can provide ten times longer lifespan.
Additionally, NSK has produced the software the ABLE-Forecaster (Advanced Bearing Life Equation) to be able to calculate the estimated life of a bearing and STIFF, which examines mechanical flaws and distortions in shafts and housings, improper placements, misaligned bearings and function faults.
Super-TF steel fixes the issue of untimely bearing malfunction taking place because of contaminated lubricant or lack of lubricant. Working conditions of dirt, dust and rigor, which cause lubricant to become contaminated, can make bearing failure predictable. Small bits of particles damage raceway surfaces inflicting stress and damage by creating indentations. Furthermore, metal surfaces may possibly rub together and peel off a layer, if the lubricant being used be too thin. Once again, stress intensifies at the damage points, and eventually fractures form at the most stressed places, and this then will increase the rate of destruction, and soon the bearing malfunctions; its life is cut short.
The secret to Super-TF steel is a unique and specialized microstructure that enables the metal to reduce the stress at the dented regions. Containing a large amount of retained austenite and elevated hardness, this surface is able to resist the dirt particles of contaminated lubricant as well as the effects of insufficient lubricant.
Super-TF technology is at this time being used by other manufacturers for use where lubrication conditions are very poor. Bearings now being made with super-TF technology include cylindrical roller bearings, deep groove ball bearing and angular contact ball bearings and, in particular, Timken uses Super-TF in its tapered roller bearings. Super-TF bearings are broadly used and highly valued in a variety of applications where bearing-longevity is highly regarded.
