Ceramic Bearings

[Sofistioelevib]

Hello guys,
what do you think about ceramic Bearings frequencies? The fault frequencies are the same as normal bearing?

What frequencies are for HBC 7019

Thank you

 

[Strong]

Here is one link to bearing:

https://www.lily-bearing.com/cerami...tact/7019-ceramic-angular-contact-bearings-3/

Fault frequencies are the same as long as the geometry/dimensions and shaft speed are the same.

Walt

 

[Sofistioelevib]

Thank you Strong

Normally the first stage for bearing problem show defect sidebands around natural frequency of the bearing.
I suppose the Natural frequency of this ceramic bearing will be different from steel one.
Do you have any experiencies about this HBC 7019 natural frequency will be in the spectrum?

Roberto

 

[claudione]

Hello Roberto and Walt,
I'm interested in bearings with ceramic spheres,......... I follow


Claudio

 

[Sofistioelevib]

Perfect Claudione,
nice to hear you

 

[Strong]

Early stage bearing defect may be detected by excitation and modulation of the race/ring natural frequencies. A hybrid ceramic bearing has only ceramic balls, and the races/rings are made of steel, so no significant difference in their natural frequencies; except dimensional.

https://www.cbrbearing.com/ceramic-hybrid-ball-bearings

What is your real concern about ceramic bearing fault detection?

Walt

 

[Sofistioelevib]

This is my first experience with ceramic bearing and i think no differencies or big differencies are between common bearing.
Due to my inexperience i only would like to know if i can go into diagnostic error using the standard vibration analisys methodology.

Roberto

 

[claudione]

I have to acquire measurements for the first time on a turbine fan,
so I wanted to first have information on ceramic bearings.

The bearing supports are inside the machine pipe,
therefore not being able to acquire measurements from outside the duct,
I will use the cable already installed that goes to DCS to acquire data, if compatible!


Claudio

 

[Sofistioelevib]

Hello Claudio,
i suppose your bearing is anyway near to external of duct structure.

Where the sensor installed?
Is close to bearing?
The data goes to DCS is conditioned to 4-20 ma or it is a real voltage coming out from sensor?

Give more detailed informations

Thnak you

 

[Strong]

Be aware that you cannot do waveform/spectrum analysis from a 4-20 ma current signal!! If the accelerometer has an AC output or is connected to a transmitter with AC output, then that is where spectrum and waveform measurements can be made.

Walt

 

[claudione]

I organize for tomorrow acquire the measures and then the condivido.........se my program does not change!
Thanks for now


Claudio

 

[Sofistioelevib]

Walt,
i agree with you about you can acquire data on 4-20 mA but i think using the Voltage coming out from sensor it is better.
First because (but this could be opinable) 4-20 ma have less speed change respect the mV.
Secondly because for a very big increment the 4-20 mA sensor could go into saturation instead of Voltage that normally have a very big high spot G's value
Furthermore the S/N ratio (on the sensor) is bigger than 4-20 mA because ther are no conversion (all sensor pickup convert signal into a tension before everything)

 

[claudione]

Sorry for my English, I did the measurements

 

[Strong]

Roberto,

I assume you are agreeing with me. Now the machine gun; is that shooting at me or protecting me?

Walt

 

[Sofistioelevib]

@Strong: this unit is the same for the post

https://www.eng-tips.com/viewthread.cfm?qid=444631

with motor @9600RPM
@Strong....the gunman was only for the "Strong"
For this reason (driving @160Hz) probably the bearing are in ceramic material (for the eddy currents generated).

Another questions is consequent:

The ceramic balls prevent eddy current but at this speed is not too dangerous? i'm not experienced but i think at this speed when bearing fault start degenerate in a very few time, isn't it?​

Could you share your experienced in ceramic bearing fault?

thank you

 

[claudione]

The sensors 100mV/g are set outside the support.
The machine is a turbofan, 9.600 rpm with inverter 160 Hz, bearing FAG HCB 7019-C-T-P4S-UL.