SKF - Rolling Bearings

6 Needle roller bearings
Temperature limits
The permissible operating temperature for
needle roller bearings can be limited by:
• the dimensional stability of the bearing
rings and rollers
• the cages
• the seals
• the seating rings
• the lubricant
When temperatures outside the permissible
range are expected, contact the SKF application
engineering service.
Bearing rings and rollers
SKF needle roller bearings undergo a special
heat treatment. The bearings are heat stabilized
up to at least 120 °C (250 °F).
Drawn cup needle roller bearings are heat
stabilized up to at least 140 °C (285 °F).
Cages
Steel cages can be used at the same operating
temperatures as the bearing rings and rollers.
For temperature limits of polymer cages, refer
to Cage materials († page 152).
Seals
The permissible operating temperature for
seals depends on the material:
• NBR seals:
–40 to + 100 °C (–40 to +210 °F)
Temperatures up to 120 °C (250 °F) can be
tolerated for brief periods.
• PUR seals:
–30 to +100 °C (–20 to +210 °F)
• FKM seals:
–30 to +200 °C (–20 to +390 °F)
Seating rings
The permissible operating temperature for
seating rings fitted to alignment needle roller
bearings is –30 to +100 °C (–20 to +210 °F).
SKF greases are provided under Lubrication
(† page 239).
When using lubricants not supplied by SKF,
the temperature limits should be evaluated
according to the SKF traffic light concept
(† page 244).
Permissible speed
The permissible speed can be estimated using
the speed ratings listed in the product tables
and applying the information provided under
Speeds († page 117). If no reference speed is
listed in the product tables, the limiting speed
is the permissible speed.
Design of bearing
arrangements
Abutment dimensions
Needle roller and cage assemblies
Needle roller and cage assemblies should be
guided axially by the fine turned and polished
surfaces of adjacent machine components. For
high-speed operations they should be hardened
and ground. Appropriate abutment diameters
are provided in table 14.
Interruptions in the surface of adjacent
machine components should be avoided. Snap
rings can be used in less demanding applications,
otherwise an intermediate ring, e.g. a
spring steel washer, should be mounted
between the snap ring and the cage assembly.
Needle roller bearings with machined rings,
without flanges
The cage of needle roller bearings without
flanges should be guided axially by the fine
turned and polished surfaces of adjacent
machine components. Appropriate abutment
diameters are listed in the product tables.
Lubricants
Temperature limits for the grease used in
capped needle roller bearings are provided in
table 4 († page 698) and for full complement
drawn cup needle roller bearings in table 1
(† page 679). Temperature limits for other
714