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SEE
Technology > FAQs
On
this page we have listed 13 of the most common questions about SEE
Technology. If you don't find what you're looking for here, please contact
us
1.
What does SEE Technology detect?
SEE
Technology detects rotational impact signals. It enhances such phenomena
such as:
>
Bearing Defects
>
Gearbox Defects
>
Cavitation
>
Metal Rubbing
>
Flow (solids in liquids)
Since SEE "hears" signals of the impact type, it allows early
warning of developing damage.
2.
What bearing damages generate a SEE signal?
Bearing
problems such as:
> Holes
> Cracks
> Spalls
> Dirt
> Material
Rubbing
Other defects in:
> Belts
> Felts
> Felt
Rollers
> Chains
Chipped teeth in gears
3.
Can SEE readings be trended?
Yes,
keeping in mind that amplitude readings may decrease as damage becomes
severe due to smoothing of crater edges with a corresponding improvement
in lubrication flow and a minimising of metal-to-metal contact. At the
early stages of damage, however, readings should be trendable.
4.
Do larger SEE readings imply a larger stress-type defect?
A
larger SEE reading implies a higher stress defect. Again, keep in mind
that amplitude readings may decrease as damage becomes severe due to
smoothing of crater edges with a corresponding improvement in
lubrication flow and a minimising of metal-to-metal contact.
5.
On what applications should SEE measurements be performed and on which
ones can it not be done?
SEE
measurements are most significant on stress-type defects; -such as the
signals generated by metal-to-metal contact, cavitation, and electrical
noise. SEE measurements do not reflect significant readings in
applications which look at other things besides stress defects, such as
misaligrunent, gear backlash, and applications on very slow speed
machinery.
6.
In which applications does a SEE signal give sufficient information about
rolling element bearing condition and in which applications is enveloping
not enough?
SEE
measurements give excellent information in the early warning stages of
bearing defects involving highly loaded applications with loss of
lubrication. Speed is not important nor is the stiffness of a machine
(which transmits small vibration readings). If these measurements
indicate an incipient failure, SEE spectrum analysis would confirm the
diagnosis.
7.
How should SEE measurements with a fixed sensor be performed?
A
good coupling path is important.The conductive path is improved by a
thin layer of recommended grease or oil.
8.
How should SEE measurements with a hand-held sensor be performed?
SEE
measurements with a hand-held sensor must be consistently applied to
achieve trendable readings. Each measurement POINT requires constant
sender pressure (2.2Ibs or 10 N force) of the sensor against the
machine, the same angle of attack (90º ± 10º), the same type of probe
coupling (magnetic vs. non-magnetic), clean measurement area (surface
dirt and paint can be a problem), at the same place on the machine each
time, and good grease transmission between sensor and test surface.
9.
Is there a difference between hand-held and fixed sensor SEE readings?
Yes.
Because the efficiency of the coupling interface for hand-held and fixed
sensors differ, their amplitude readings may differ by a factor of 2 or
3. However, absolute amplitudes are not as significant as changes in
amplitude measured over time by the same sensor/couplant combination
(trend).
10.
What training and knowledge is required to take measurements and to
interpret SEE readings?
Virtually
no training is required to take the readings except to minimise the
variables in measurement setup and methods, such as location of points
on the machine to be measured, direction to hold the sensor, and
pressure of the sensor against the machine. Experience and practice
insures measurement accuracy and stability.
A
SEE reading means something is going on. Interpretation of SEE spectrums
requires a knowledge of machine components and their defect frequencies.
You could plan to attend a formal training session by Apt Technology
where you will learn basic bearing fundamentals and the fundamentals of
the equipment, such as signals in which frequency content is important,
how to be consistent, what SEE readings mean, trending, limitations of
the technology, and so on. Subscribe to, and read, as many industry
publications as you can. Attend as many industry sponsored conferences
and seminars as you can.
Your
return on the use of these tools is directly proportional to your
efforts to learn about them.
11.
How do SEE readings correlate with normal vibration measurements and
acceleration envelope measurements?
Normal
vibration measurements allow you to isolate low-frequency vibration
signals for predicting machine problems in the 1X to 10X range. In the
early stages of bearing and gear problems, enveloping and SEE Technology
will provide indications of some defective performance. In the more
advanced stages of bearing and gear degradation, normal spectrum
analysis might reveal some insight as to the extent of damage.
SEE
measurements do not necessarily correspond with low-frequency
measurements or with envelope measurements. In many cases, loss of
lubrication, for example, cannot be seen by enveloping or low-frequency
measurements.
SEE
Spectrum analysis can often confirm bearing or gearing defects by their
defect frequencies. Because these measurements have different goals,
they measure different things. You should use all these technologies in
your predictive maintenance program to maximize your ability to predict
problems and to maximise your cost savings.
12.
What bearing defects generate only SEE signals?
Metal
rubbing, contamination of lubricant, or lack of lubricant generate SEE
signals. These warn of future problems even before any problem exists.
13.
What sensitivity is required for a SEE sensor?
The
sensitivity of the standard SEE sensor has been selected based on the
SEE Technology circuitry and on a number of test applications such as:
>
Papermill Dryer Section
>
Papermill Wet Section
>
Compressors
>
Separators
>
Stone Crunching
>
Locomotives
>
Pumps and Blowers
>
Auto Wiper Motors
>
Auxilliary Equipment
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