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1.7: Determination of Defect Frequencies and Energy Levels

By Har Prashad
From Solving Tribology Problems in Rotating Machines

1.7 Determination of Defect Frequencies and Energy Levels

1.7.1 Theoretical

Defect frequencies at different speeds of operation were theoretically determined for the NU 330 type of bearing by using the formulae given in Section 1.3. Four bearings of type NU 330, under identical conditions of operation in the coupled mode for the motor, were considered: bearing 'A' (new), bearing 'A' (defective), bearing 'B' (new) and bearing 'C' (defective). The defects of bearings 'A' (defective) and 'C' (defective) were known, bearing 'A' (defective) having a through crack in the inner race and bearing 'C' (defective) having score marks on the rollers. Table 1.1 shows the defect frequencies at different speeds of operation for NU 330 bearings.

Table 1.1: Theoretical determination of defect frequencies at different operating speeds for NU 330 bearing

Defect frequency

Frequency (Hz) at different speeds of operation (rpm)

1000

1800

2250

2750

f s

16.67

30.00

37.50

45.83

f c

6.67

12.0

15.2

18.3

f b

42.5

76.5

95.8

116.9

f ORDFL (L 1, L 2)

93.4

168.0

214.0

256.0

186.8

336.0

428.0

513.0

f bf

85.0

153.0

191.0

235.8

f IRDFL (L 1, L 2)
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Topics of Interest

1.8 Results and Discussion Tables 1.2 to 1.5 and Fig. 1.4 to 1.13 show the following: In the spectrum of bearing 'A' (new), certain defect frequencies such as RW, ORDFL, RRS, IRWL appear...

1.9 Conclusions and Recommendations Based on this study and analysis, the following major conclusions are drawn:8,9 Data brought out in this study can be used for appropriate bearing...

3.1 A General Review This chapter explains the effect of cage and roller slip on the measured defect frequency response of rolling-element bearings using the high-frequency resonance technique...

1.3 Detection of Bearing Malfunction and Determination of Defect Frequencies In general, the possible causes of bearing failure include excessive contact stresses, misaligned loads, material flaws,...

1.1 A General Review Investigations employing the high-frequency resonance technique (HFRT), which diagnoses defect frequencies of rolling-element bearings of different makes, have been carried out.