Page 1046 - Rollingbearings

21 Hybrid bearings

Mor Hybrid bearings have rings made of bearing • Reduced risk of smearing
More informatione information
steel and rolling elements made of bearing Even under inadequate lubrication condi-
grade silicon nitride (Si N ), which make the tions, such as high speeds and rapid accel-
3 4
Bearing life and load ratings al bearing knowledge 63 bearings electrically insulating. erations, or where there is an insuficient
17
Gener
hydrodynamic ilm, the risk of smearing is
59
B 59 Bearing features reduced between silicon nitride and steel
Design considerations earing selection process
109
Bearing systems ubrication
L 160 surfaces For conditions where κ < 1, it is
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Recommended its earing interfaces 13 Silicon nitride rolling elements can extend common to apply κ = 1 for hybrid bearing
B
Abutment and illet dimensions at tolerances for standard
Se 208 bearing service life by offering enhanced life calculations (Lubrication condition –
conditions 148 bearing performance, even under dificult the viscosity ratio, κ, page 102)
Lubrication 239 operating conditions When compared to
Selecting internal clearance or
preload 182 same-sized bearings with steel rolling elem- • Reduced risk of false brinelling
Sealing, mounting and ents, the beneits of hybrid bearings include: When subjected to vibration, hybrid bear-
Mounting, dismounting and
193
bearing care
dismounting 271 ings are signiicantly less susceptible to
Mounting instructions for • Protection from electric current false brinelling (formation of shallow
individual bearings † skf com/mount damage depressions in the raceways) between the
Mounting instructions for
individual bearings † skf com/mount
SKF bearing maintenance Hybrid bearings are non-conductive and silicon nitride and steel surfaces
handbook (ISBN 978-91-978966-4-1) therefore suitable for applications such as
SKF bearing maintenance AC and DC motors and generators, where • Less sensitivity to temperature
handbook ISBN 978-91-978966-4-1 electric currents are present gradients
21 Silicon nitride rolling elements have a
• Higher speed capability lower coeficient of thermal expansion,
The density of a silicon nitride rolling elem- which means they are more stable over
ent is 60% lower than a same-sized rolling temperature gradients within the bearing
element made of bearing steel Lower and provide more accurate preload/clear-
weight and inertia translates into higher ance control
speed capability and superior behaviour
during rapid starts and stops
• Long service life
The lower frictional heat generated in
hybrid bearings, especially at high speeds,
contributes to extended bearing service
life and extended relubrication intervals
• High wear-resistance
Silicon nitride rolling elements have a
higher degree of hardness making hybrid
bearings suitable under dificult conditions
and contaminated environments

• High bearing stiffness
With a high modulus of elasticity, hybrid
bearings offer increased bearing stiffness

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