Vibration Institute
Piedmont Chapter 14
Barry Schoch
PREDICT
Ferrography / Used Oil Analysis
February 25, 2005
Phone 800-543-8786
www.predictusa.com
“First Sample in your Trend”
What your Lab can
and
cannot tell you
Why Do Ferrography / UOA?
To Identify Abnormal Wear
Conditions Before They Become
Significant Enough To Adversely
Effect Component Life.
Used Lubricant Analysis
Trends the physical properties of the
lubricant
Determines the chemical breakdown or
contamination of the fluid
Determines the concentration of dissolved
elements & additives
UOA Tests
•
•
Oil Bath
RDE Spectrometer
 Viscosity
 Elemental Concentration
•
FTIR Spectrometer
•
Titration
– TAN & TBN
 Oxidation, Nitrates, Sulfates,
Water, Fuel, Glycol, Additive
Degradation
•
 Acid & Base Level Trends
Water
– Crackle
– Karl Fischer
 Concentrations to 800ppm
 Concentrations to 10ppm
•
Particle Count
 NAS & ISO Cleanliness Ratings
•
•
Gas Chromatography
Flash Point
 Fuel Dilution
Observations
• Large particles in sample
– Likely to settle in sample bottle
– Particles over 80 microns are easily visible to
naked eye
Observations
• Crackle Test
– Hot Plate set at 115-125C
– Sensitive to between 800 and 1000 ppm depending on
oil viscosity and additives
Viscosity
ASTM D-445
Constant Temp.
Oil Bath
40oC or 100oC
Nametre Oscillation
Viscometer
Non-ASTM Test
Ambient Temp.
• Measure of shear rate
vs. shear stress; i.e.
resistance to flow
• Measured at constant
temperature (40oC or
100oC)
Emissions Spectrometer
(ELEMENTAL SPECTROSCOPY)
EXCITATION SOURCE
ICP
LIGHT EMISSIONS
AA
RDE
DIFFRACTION
GRATING
DETECTORS
SIGNAL PROCESSING
FT-IR: Used Mineral Oil Spectrum
Water by Karl Fischer Titration
Particle Count Test Results
This shows a typical print
out from a particle counter
displaying results by number
of particles in any one
group.
Total Acid Number
• TAN looking for acidity changes
– In this application, more likely to find
oxidation products
– Acid contaminant likely only through process
contamination
– Causes corrosive wear debris and general
increases in the wear rate
Total Base Number
• TBN looking for alkalinity
– Overbase additive applications most likely
(Large Diesel Engines)
– Absence of additive (low TBN) will cause
increases in rates of wear, corrosion, and solid
combustion product generation
– Process contamination possible, but not
observed
Ferrography
• Separation of Wear Debris from Lubricant
• Quantitative and Qualitative evaluation of Wear
Debris using Trend Analysis
• Assessment of the Severity, Origin &
Development Mechanism of Particles;
• Predict Equipment Wear Condition & Failure
Potential
Wear
• Results from ordinary wear or equipment damage
• Missing volume goes into the lube system in the
form of fine particles
• Wear is generated initially as small particles over
time, not large chunks
Wear
• Since most of the wear debris is some form of
steel, a magnetic field is used for separation
• Debris is so small that a high gradient field
rather than a steady field is required
• Larger particles are affected more strongly than
smaller ones, so a rough separation according to
size is possible
DR Ferrograph
• Uses optics to determine concentration of wear debris
• Is able to evaluate concentrations of magnetically
attracted wear debris
• Particle size limitation is 300 microns
• Effective trending tool for most types of industrial
equipment
• Limitations are for extremely clean lube systems, i.e,
hydraulics, some turbines
DR Acceptance Limits
WEAR PARTICLE CONCEN. ACCEPTANCE LIMITS
Vacuum Pumps
WPC = 1-5
Boiler Feed Pumps
WPC = 1-100
Gas Compressors
WPC = 1-50
Turbines
Fans
Journal Bearings
WPC = 1-20
Roller Bearings
WPC = 5-100
Engines
WPC = 10-150
Transmissions
Extruder Gearboxes
WPC = 100-600
Dragline Gearboxes
WPC = 1,000-50,000
Hoist Gearboxes
Analytical Ferrography
• View slide made by FM
• Several magnifications
–Speed
–Detail
• Identify debris using
–Reflected light
–Transmitted light
–Polarized light
–Color filtered light
BEARING WEAR
Copper Alloy
Steel Prior to Heat Treatment
Low Alloy Steel
Lead/Tin Babbitt Metal
Analytical Ferrography
Particle Classification
•
•
•
•
Size
Shape
Concentration
Composition
Analytical Ferrography
Rating 1
Rating 6
Rating 2
Rating 7
Rating 3
Rating 8
Rating 4
Rating 5
Rating 9
Rating 10
Analytical Ferrography
Correlation w/ DR Ferrograph
WPC=10
WPC=50
WPC=100
WPC=500
WPC=1000
Equipment
Condition
Report
Equipment
Condition
Report
(cont)
Summary
First Sample Analysis
Yes
No
• Detect Dissolved up to
8mm Particles
• Problems detecting Onset
of Abnormal Wear
• Determine Lubricant
Additive Depletion
• Determining Sources of
Wear (bearings, gears,
seals, rings, etc.)
• Detect Fluid
Contamination
• Determine Lube Physical
Condition
• Reliable Estimate of
Machine Wear Condition
First Sample Analysis
• Observation i.e., water, large
particles
Yes
• Viscosity
Yes
• RDE Spectroscopy (21 metals)
Limited
w/ Ref.
First Sample Analysis
• FT-IR Spectroscopy
No
• Water by Karl Fischer Titration
Yes
• TAN, TBN
No
• DR Ferrograph
Limited
• Analytical Ferrography
Yes
Questions