SPM SC presentation 12 2008

The dBc value is effected by the lubrication condition in a bearing.. Properly sized shaft and housing fitsGeometric quality of bearing Total load Rolling velocity Contaminants in Lubri

Shock Pulses

0 5000 1 104 1.5 104 2 104 2.5 104 3 104 3.5 104 4 1040

Shock Pulse Transducer

0 100 200 300 400 500 600 700 800 900 1000 0

0.2 0.4 0.6

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 2

0 2

Bearing damage Unbalance

Unbalance

Bearing damage

Hz

Band pass filter

Enveloping at a Resonance Frequency

Peaks around the resonant frequency

0 5000 1 104 1.5 104 2 104 2.5 104 3 104 3.5 104 4 1040

0.05

Hz

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 2

0

Bearing damage

Bearing damage

0 0.1

II Frequency domain

0

0.1

dBmdBc

Hz

I Time domain (SPM)

0 0.1

The dBc value is effected by the lubrication condition in a

bearing It is commonly referred to as the background noise or

the carpet noise of a bearing

about a 1000/sec an average of all the lower Shock Pulses

dBc

dBc

Full film lubrication

Partial lubrication

Boundary lubrication

Properly sized shaft and housing fits

Geometric quality

of bearing

Total load Rolling velocity

Contaminants in Lubricant film

Surface finish Cleanliness

Things that effect the Lubricant film thickness

The dBm value indicates the bearing operating

condition once a measurement is completed The dBm is commonly referred to as the Max value

On the Infinity, the LED s and the color coded

dots to the left of the measuring results indicate

the operating condition.

dBc

dBm

calculated by sampling the incoming signal

approximately 50/ sec

an average of all the stronger Shock Pulses

dBc

SPM Evaluation Scale

The dBi value is calculated once the RPM and Shaft Diameter have been input into the instrument or software.

Normalized measuring scale: dBsv = dBn + dBi

60 Green Yellow - Red scale.

-Time

SPM recommends changing the bearing when dBm reaches 55

Red - Bad (dBm 35 and more)

Yellow - Caution (dBm 21 to 34)

Green - Good (dBm up to 20)

Bearing Operating Condition:

1 2 3

Small delta with elevated dBm/dBc readings typically indicate lubrication problems

Large delta (15 or >) with elevated dBm/dBc readings indicate possible bearing damage or other mechanical problems

Low dBm/dBc readings with small delta indicates a good bearing

Bearing Lubricated because dbc reading increased it also drove up the dbm.

SPM dbm/ dbc trend graph

Bearing replaced

Signal Source?

Is the Red or Yellow SPM Reading from the bearing or outside source?

SPM Spectrum used to confirm bearing and lubrication concerns

SPM Spectrum with Bearing Symptom in software