Upgraded rollers provide substantial improvements

FA tapered roller bearings are designed to provide the long service life and performance needed for automotive transmissions and differential gears. In bearings, the precision of the rolling elements has the greatest effect on smooth rotational operation. And although roller bearings generally cannot achieve the precision of ball bearings, upgraded rollers can provide substantial improvements in rotational performance. For tapered roller bearings, where sliding contact exists between the roller ends and the inner race's rib, it is especially important to optimise the precision of roller ends. Bearing drag torque, resistance to seizure and preload parasitic losses are all greatly affected by the precision of the roller ends. Three years ago, NTN Corp started work on machining technology to improve roller precision. Now, NTN is successfully mass-producing super high precision rollers with about four times the precision and one-third the surface roughness of conventional rollers. This success was achieved by developing a production system that uses new machining technology to upgrade significantly the spherical surface precision of the roller ends. In addition, NTN's proprietary "FA" heat treatment process produces ultrafine austenite grains in bearing steel to ensure long bearing life. The combination of this special heat treatment and high precision rollers has resulted in the world's highest quality roller bearings. The performance of NTN's "FA tapered bearings" is superior to conventional bearings made with standard carburised steel for the following reasons: bearing life is approximately 14 times longer under impurity mixture lubrication conditions; drag torque is reduced 10% or more; resistance to seizure is improved by about 25% while doubling the allowable surface pressure; preload parasitic losses have been reduced by approximately 50%. The number of revolutions to achieve bearing stand height stabilisation in assembly were have been by approximately 50%. The longer service life and performance also allow the bearing to be down-sized as necessary. Production is scheduled to start in December 2004. This tapered roller bearing will be standard for automotive transmission and differential gear applications. NTN's FA tapered roller bearings will be shipped all over the world and increasing sales are projected. They are designed to provide the long service life and performance needed for automotive transmissions and differential gears and other applications for tapered roller bearings.