How do you calculate the frequency of a bearing defect?
How do you calculate the frequency of a bearing defect?
Formulas for the calculation of the bearing failing frequencies
- BPFO=0.4×NB×RPM.
- BPFI=0.6×NB×RPM.
- FTF=0.4×RPM.
Why is it important to know the fault frequencies of the bearings before analysis?
Thus, identifying these characteristics can not only help to verify that a bearing is definitely failing, but can also give some indication of the extent of the deterioration of the bearing.
How do you know when roller bearings are bad?
The most common and most easily identifiable symptom of a bad wheel bearing is an audible one. If you notice a grinding or grating noise coming from your wheel or tire, take note that this is very likely caused by a bad wheel bearing—especially if the noise gets louder as the vehicle accelerates.
What is ball passing frequency?
The ball pass frequency is the rate at which a defect in the inner or outer race comes into contact with a roller. Below are the four equations for calculating the fundamental frequencies. mechanical part, will generate natural frequencies while in operation; also known as fundamental defect frequency.
What is bearing fault frequencies?
The bearing natural frequencies depend on the dimensions of the bearings and how these are mounted. Typically, the natural frequencies can be found in the 2-6 kHz range. At the end of stage two, sidebands appear above and below natural frequencies and high-frequency detection method continues to increase.
What is ball pass frequency?
Ball pass frequency of the inner race (BPFI): It is the rate at which a ball/roller passes a defect in the inner race. The level of BPFI is often slightly lower than BPFO as the vibration is generated further away from the transducer.
What causes ball spin frequency?
The ball spin frequency is the rate at which a point of the Craft bearing’s roller comes into contact with either the inner or outer race. mechanical part, will generate natural frequencies while in operation; also known as fundamental defect frequency.
How do you check roller bearings?
In the case of small non-separable ball bearings, hold the bearing horizontally in one hand, and then rotate the outer ring to confirm that it turns smoothly. Separable bearings such as tapered roller bearings may be checked by individually examining their rolling elements and the outer ring raceway.
What causes brinelling?
True brinelling is caused by shock or excessive loads due to improper mounting, dropping of machinery during handling, excessive static or impact loads during the operating cycle.
What causes ball bearing cage failure?
Ball Speed Variation (BSV) and cage clearances affect the cage life of ball bearings. Vibration and impact of the moving surfaces of a bearing under high pressure conditions also affects the cage life. Moreover, large forces at the cage-ball and cage-race contacts cause cage failure.
What causes spalling in a bearing?
Spalling is the result of surface or sub-surface fatigue, which causes fractures to form in the running surfaces. When the rolling elements travel over these cracks, pieces, or flakes, of material break away. Surface fatigue (spalling) in recirculating ball bearings typically begins with a crack that is v-shaped (A).
What is the effect of bearing defect frequency on bearing deterioration?
The more harmonics of a bearing defect frequency, the greater the deterioration. However, rpm must also be considered. Low speed machines show considerably lower amplitudes, as well as less bearing defect harmonics, for the same deterioration as in higher speed machines. Stage Four:
What are the harmonics of the bearing fault frequencies?
First harmonics of the bearing fault frequencies BPFO, BPFI and BSF. 4.5 to 20.5x RPM. Higher bearing fault frequencies harmonics and presence of frequencies related to electrical issues. 20.5 to 50x RPM. High frequency spectral band, in units of acceleration (G’s).
What are the characteristics of a high frequency bearing?
Higher bearing fault frequencies harmonics and presence of frequencies related to electrical issues. High frequency spectral band, in units of acceleration (G’s). Alarm parameter in case of early bearing deterioration stage, presence of cavitation or lack of lubrication.
What type of seals are available on Torrington drawn cup bearings?
Sealed bearings Torrington drawn cup bearings are offered with integral seals. The tables of dimensions on page 397 indicates those sizes available with lip contact seals.
