Special Issue; Products for Industrial Machinery - NTN

Ultra-Clean Bearing for Clean Environments
oil-impregnated porous resin cage features 35% or
higher porosity thanks to a special manufacturing
technique, allowing this cage to retain more lubricating
oil. Compared to conventional ultra-clean bearings,
NTN’s new ultra-clean bearings are capable of longer
life while maintaining low dust generation in high load
applications.
Table 2 Test conditions
Test bearing Deep groove ball bearing (#608) 8227 mm
Degree of vacuum
10 -5 Pa
Running speed
500 min -1
Temperature
Ordinary temperature
Thrust load
196N
2.1 Evaluation of various characteristics
2.1.1 Evaluation of dust generation characteristics
Under the test conditions summarized in Table 1,
the test bearing was allowed to run for 150 hours, and
the amount of resultant dust generated during the
duration of the test was measured. As summarized in
Fig. 3, the dust generated with the Ultra-Clean NC
bearing was equivalent to the amount generated by
bearing types usually used for clean applications (a
low-dust-generating prefilled-grease type for vacuumuse
and a special PTFE-coated type).
2.1.2 Rotating torque
NTN evaluated the rotating torque for the Ultra-
Clean NC bearing under the test conditions
summarized in Table 2. As illustrated in Fig. 4, the
Ultra-Clean NC bearing features a lower torque
compared to the conventional bearing (special PTFEcoated
type).
Table 1 Test conditions of dust generation
Deep groove ball bearing (#608)
Test bearing
8227 mm
Degree of vacuum
10 -5 Pa
Running speed
50 min -1
Size of particles being counted 0.2m or greater
Thrust load
9.8N
Temperature
Ordinary temperature
Duration
150 hrs.
Rotating torque mNm
50
40
30
20
10
0
Ultra-Clean
NC bearing
Low-dust-generating
prefilled-grease type
for vacuum-use
Fig. 4 Results of rotating torque
Special
PTFE-coated
type
2.1.3 Endurance evaluation
Each bearing type was evaluated at each of the
three thrust load levels specified in Table 3. As can be
seen from the data in Fig. 5, the Ultra-Clean NC
bearing boasts a longer life in all three loading
Test bearing
Table 3 Test conditions of endurance test
Degree of vacuum
Running speed
Temperature
Thrust load
End of life criterion
Deep groove ball bearing (#608) 8227 mm
10 -5 Pa
500 min -1
Ordinary temperature
196N686N981N
The point when a sudden increase in torque occurred
Number of dust particles generated
1000
100
10
1
Ultra-Clean
NC bearing
Low-dust-generating
prefilled-grease type
for vacuum-use
Special
PTFE-coated
type
Life h
10000
Cessation of test run
1000
100
10
1
Ultra-Clean NC bearing
Low-dust-generating prefilled-grease type for vacuum-use
Special PTFE-coated type
Cessation of test run
Cessation of test run
196N 686N 981N
Fig. 3 Results of dust generation test
Fig. 5 Results of endurance test
-81-