Special Issue; Products for Industrial Machinery - NTN

NTN TECHNICAL REVIEW No.742006
Introduction of New Products for Machine Tools
79U/70U Type Standard Angular Contact Ball Bearings
Standard series features high-speed performance, long bearing life,
and high rigidity, which are among the best in the world
Features
¡High-speed
Maximum dmn value with air-oil lubrication
is 1.5 million
Maximum dmn value with grease lubrication
is 0.95 million
¡Longer life: 10% increase in bearing life
¡Maximum allowable axial load: 23 times
greater
Temperature increase on the outer ring ˚C
50
40
30
20
10
0
0
ULTAGE (phenol resin cage)
ULTAGE (newly designed polyamide resin cage)
Previous bearing (polyamide resin cage)
2000 4000 6000 8000 10000 12000 14000
Bearing speed min 1
Without cooling
arrangement on
the jacket
With cooling
arrangement on
the jacket
Structure
New design for molded resin cage
0 50 100
150
Test conditions
Bearing
description
Preload as mounted
Lubrication system
Air supply rate
Oil supply rate
Oil grade
Cooling arrangement
on the jacket
Applications
dmn value10 4
ULTAGE7020UCDB
Previous bearing 7020CDB
100mm150mm24mmtwo rows
Contact angle15˚
150 N (definite position preloading system)
Air-oil lubrication
40 NL/min
0.03 mL/5 min/shot
ISO VG32
Available
Fig. 1 High-speed test (air-oil lubrication)
¡Machine tool main spindles, precision machinery, etc.
Tapered bore form
Air-oil lubrication: Helps to circulate and redistribute
lubricating oil
Grease lubrication: Helps with prefilling of grease
Fig. 2 (a) New resin cage (section of the ball pocket)
Relieving on four corners
of each ball pocket
Air-oil lubrication:
promotion of discharge
of lubricating oil
Grease lubrication:
improved grease retention
Fig. 2 (b) New resin cage (appearance)
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