NSK has developed TL (Tough and
Long Life) bearing material to
address the trend to higher operating
temperatures in the dryer sections of
paper making machines, where
temperatures in the hollow cylinder
of the dryer section, through which
steam or oil passes, can reach 180°C
and, on newer machines, 200-250°C.

Such temperatures cause high
thermal stresses which NSK says can
lead to fracture of the inner rings of
spherical roller bearings. NSK
analysed the mechanism of inner
ring fracture and established a
strength evaluation method, resulting
in development of the TL material.

TL also contributes to an increased
surface hardness on the bearing
raceways and boosts dimensional
stability in temperatures to 200°C.