Shock Pulses

0 5000 1.104 1.5.104 2.104 2.5.104 3.104 3.5.104 4.104

0

0.05

Hz

UnbalancePeaks around the resonant frequency

Resonance Frequency

Shock Pulse Transducer

n

0 100 200 300 400 500 600 700 800 900 10000

0.2

0.4

0.6

0 0.005 0.01 0.015 0.02 0.025 0.03 0.0352

0

2

Bearing damage Unbalance

Unbalance

Bearing damage

Hz

Trancients Resonance

0 0.005 0.01 0.015 0.02 0.025 0.03 0.0352

0

2

UnbalancePeaks around the resonans frequency

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

4 104

0

0.05

Hz

0.1

0

0.1

Signal after band pass filter

0.1 After rectifying

0

01. After enveloping

Peak detection

0 0.005 0.01 0.015 0.02 0.025 0.03 0.0352

0

2

Bearing damage

Bearing damage

0

0.1

II. Frequency domain

0

0.1

dBm

dBcHz

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. The dBc value is calculated by sampling the incoming signal about a 1000/sec an average of all the lower Shock Pulses.

dBc

dBc

Full film lubrication

Partial lubrication

Boundary lubrication

Viscosity

Lubricant type

Temperature

Lubricant supply

Static and dynamic load

Preload Alignment 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 valueOn the Infinity, the LED s and the color coded dots to the left of the measuring results indicate the operating condition.

dBc

dBm

The dBm value is calculated by sampling the incoming signal approximately 50/ sec an average of all the stronger Shock Pulses.

dBm

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

-9

dBsv 100

33 dbc

51 dbm

dbi 15

36 dbm

18 dbc

dBn 60

0

This becomes the starting

point for the 0 60 Green -

Yellow - Red scale.

Time

SPM recommends changing thebearing 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 graphBearing 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

Add bearing coefficients in software to

utilize Bearing Symptom feature

SPM Spectrum with Bearing Symptom in software

Bearing Symptom

matches up with FTF in

this example confirming

bearing damage.