2. Lubrication Related Failures
• The majority of
premature bearing
failures are lubrication
related
– Under lubricated
– Over lubricated
– Wrong lubricant
– Lubricant
contamination
Source: "Pump Users Handbook: Life
Extension” 2011 by Heinz Bloch
3. Lubrication Related Failures?
“as many as 60 to 80 percent of all bearing
failures (catastrophic, functional and premature)
are lubrication-related, whether it's poor lubricant
selection, poor application, lubricant
contamination or lubricant degradation1.”
1 Mark Barnes, “What Exactly is a Lubrication Failure?”
Machinery Lubrication, formerly of Noria Corporation
4. Ultrasound Assisted
Lubrication
In this presentation we will discuss:
• What is Ultrasound Assisted Lubrication
• Ultrasound Technology and Instruments
• The advantages of Ultrasound
• Procedures for Ultrasound Bearing
Inspection and Lubrication
5. Ultrasound Assisted
Lubrication
• Traditional lubrication programs include
preventive procedures that include time-
based lubrication.
– Lubrication is performed at set timed intervals
with a specified amount of grease applied
6. Ultrasound Assisted
Lubrication
• The issue with time-based lubrication is,
what if the bearing being lubricated has a
sufficient amount of grease already and
therefore DOES NOT need lubricant. This
produces an inherent risk of Over-
Lubrication.
7. Ultrasound Assisted
Lubrication
• Another issue is the time-interval for
lubrication. Is it correct?
– What if some bearings require lubricant to be
applied more frequently than assumed or
what if the time interval can be stretched out?
8. • These issues do not preclude the need for
standard preventive procedures such as
calibrating grease guns, measures to
ensure the correct lubricant is used for the
correct application, etc…
• The concept is to assist current lubrication
procedures with the addition of ultrasound
technology
Ultrasound Assisted
Lubrication
9. What is Ultrasound Assisted
Lubrication?
• Adding ultrasound monitoring to standard lubrication
best practices can prevent potential over lubrication of
bearings which can also lead to fewer bearing failures,
extend motor and bearing life as well as lead to a
decrease in the amount of lubricant used
This will produce:
• Savings in maintenance costs, lubricant, man-hours
• And improved asset availability and reliability
11. • Airborne & Structure-Borne Ultrasound
instruments sense friction.
• Trending associated amplitude levels and
changes in sound quality of a bearing
provide early indication of conditions such
as lack of lubrication and prevent over-
lubrication
What is Ultrasound Assisted
Lubrication?
12. • High frequency sounds that are above the
range of human hearing
– The ultrasonic range begins at 20 kHz
• There are three Generic Divisions of
Ultrasound:
– Pulse/Echo
– Power
– Airborne/Structure Borne
What is Ultrasound?
13. • Provides Earliest Warning of Failure
• Isolates Signal
• Quality of Bearing
• Detects Lack of Lubrication
• Finds defects not found in time based lube
routes
Ultrasound Advantages
14. • Prevents Over Lubrication
• Can Be Used on Slow Speed Bearings
• Complements Other Technologies
– Thermography
– Vibration Analysis
– Oil Analysis
Ultrasound Advantages
16. How Ultrasound Instruments
Work
• Instruments based on airborne & structure borne
ultrasound sense high frequency emissions produced by
turbulence (from leaks), friction (in mechanical
equipment) and ionization (generated by electrical
emissions)
• They translate these sounds down into the audible range
through an electronic process called “Heterodyning”
• Sound is measured by a decibel level that is indicated
onboard the instrument
17. How Ultrasound Instruments
Work
• The heterodyning feature enables users to hear the
translated signals in headphones, record sound samples
and analyze sounds through spectral analysis software.
• Data from test results can also be viewed on a display
panel
18. Sounds Are Received Two Ways:
-Through a
contact
module or
wave guide
-Through a
scanning
module
19. • Digital instruments:
– Set baselines
– Log data
– Record sound sample
– Analyze Sounds
– Download all data to Data Management Software
Instruments used for
Lubrication Programs
dB Level
20. • Data Logging
• Sound Recording
• Data Management Software
– Improved Record Keeping, Recording, Reporting
• Spectral Analysis
Digital Instruments
26. • 8 dB Lubrication
• 12 dB Minor Damage-Microscopic Faults
• 16 dB Damage-Visual Faults
• 35+ dB Catastrophic Failure Imminent
Action Levels
Lack of
Lubrication
Microscopic
Damage
Damage
(visual)
Severe
Failure
27. • After review of data
– Sect bearings in need of action for either:
– Repair
– Lubrication
Procedure
28. • Assign analog ultrasound
instrument to lube
technicians
• Instruct them to add
enough lubricant to
cause a drop in sound
levels while observing
the LED intensity
indication
• Add lubrication – Meter
intensity levels drop
• Use caution - Lubricate A
little at a time
Procedure
29. • If bearing needs grease, dB will decrease
as lubricant is applied
• If bearing is already over lubricated, dB
will start to increase while applying
lubricant
• If there is no change in dB, further action
should be taken to see why there was no
change, or bearing is in a failure mode that
lubrication is not the solution
Procedure
30. Examples of Over Lubrication
The biggest problem we find in bearings is that they are over
greased. The maintenance man doing the greasing usually does
not know how much grease is put into the bearing. In the past we
just pumped a few strokes into the bearing and then said well that
ought to do it. Usually that was too much grease and these
pictures show the results of that style of greasing.
31. In the case of this motor there was no attention paid to how much
grease was being put into the bearing. This motor actually had
shielded bearings in it and there was no grease getting into the
bearing, so it never cooled down and never got any quieter so they
just continued to grease it. After a point, there was so much grease
in it that the motor started to heat up. What did they do then?
THEY GREASED IT SOME MORE.
Examples of Over Lubrication
32. Ultrasound Assisted
Lubrication Best Practices
• Prioritize equipment based on an asset
criticality list
– Likelihood of a failure, runtime, cost to repair,
consequences of a failure
• Set up routes to collect ultrasound data
including recording sound files
• Once initial readings have been taken, a
baseline is set
33. • Once a baseline has been established,
alarm levels are set
• Data (dB) only is collected until an alarm
has been reached
• Ultrasound is used to lubricate points that
are currently in a “low alarm” condition
• Grease is applied until the dB returns to
the normal level
Ultrasound Assisted Lubrication Best
Practices
34. • For more critical assets, a follow up
reading should be taken to ensure that the
dB did not rise again after lubrication, or
use a complementary technology for a
“second opinion”
• PM’s may need to be adjusted to reflect
the use of ultrasound while greasing,
frequency, type of lubricant, etc…
Ultrasound Assisted Lubrication Best
Practices
35. Benefits of Ultrasound
Assisted Lubrication
• Identifies bearings in need of lubrication
• Prevents over lubrication of bearings
• Reduces the amount of grease kept in
inventory
• Reduces incidents of bearing failure
• Reduced labor lubricating bearings
• More effective PM’s
• Improves asset availability
Vibration can’t do slow speed. Need to catch bearing before it goes catastrophic.
Brinelling of bearing surfaces will produce a similar increase in amplitude due to the flattening process as the balls get out of round. These flat spots also produce a repetitive ringing that is detected as an increase in amplitude of monitored frequencies.
The ultrasonic frequencies detected by the Ultraprobe are reproduced as audible sounds. This “heterodyned” signal can greatly assist a user in determining bearing problems. When listening, it is recommended that a user become familiar with the sounds of a good bearing. A good bearing is heard as a rushing or hissing noise. Crackling or rough sounds indicate a bearing in the failure stage. In certain cases a damaged ball can be heard as a clicking sound whereas a high intensity, uniform rough sound may indicate a damaged race or uniform ball damage. Loud rushing sounds similar to the rushing sound of a good bearing only slightly rougher, can indicate lack of lubrication. Short duration increases in the sound level with “rough” or “scratchy” components indicate a rolling element hitting a {flat spot and sliding on the bearing surfaces rather than rotating. If this condition is detected, more frequent examinations should be scheduled.
Vibration can’t do slow speed. Need to catch bearing before it goes catastrophic.
Brinelling of bearing surfaces will produce a similar increase in amplitude due to the flattening process as the balls get out of round. These flat spots also produce a repetitive ringing that is detected as an increase in amplitude of monitored frequencies.
The ultrasonic frequencies detected by the Ultraprobe are reproduced as audible sounds. This “heterodyned” signal can greatly assist a user in determining bearing problems. When listening, it is recommended that a user become familiar with the sounds of a good bearing. A good bearing is heard as a rushing or hissing noise. Crackling or rough sounds indicate a bearing in the failure stage. In certain cases a damaged ball can be heard as a clicking sound whereas a high intensity, uniform rough sound may indicate a damaged race or uniform ball damage. Loud rushing sounds similar to the rushing sound of a good bearing only slightly rougher, can indicate lack of lubrication. Short duration increases in the sound level with “rough” or “scratchy” components indicate a rolling element hitting a {flat spot and sliding on the bearing surfaces rather than rotating. If this condition is detected, more frequent examinations should be scheduled.
From the field
Pre-failure- 8 dB This is the earliest stage of failure. The bearings may have developed hairline cracks or microscopic spots that are not visible to the human eye. This may also signal a need to lubricate.
Failure Stage - 16 dB At this stage, visible flaws develop along with a marked rise in acoustic energy and the temperature of the bearing begins to rise. It is at this stage that the bearings should be replaced or more frequent monitoring should occur.
Catastrophic Stage - Catastrophic Failure - 35-50 dB Here, rapid failure is imminent. The sound level is so intense as to be audible and the temperature of the bearings has risen enough to overheat the bearing. This is a highly dangerous stage since the bearing clearances increase and can cause additional friction / rubbing within a machine causing potential damage to other components.
