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

• Oil Bath • RDE Spectrometer

• FTIR Spectrometer

• Titration– TAN & TBN

• Water– Crackle – Karl Fischer

• Particle Count

• Gas Chromatography• Flash Point

UOA Tests Viscosity Elemental Concentration

Oxidation, Nitrates, Sulfates, Water, Fuel, Glycol, Additive Degradation

Acid & Base Level Trends

Concentrations to 800ppm Concentrations to 10ppm

NAS & ISO Cleanliness Ratings

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

• Measure of shear rate vs. shear stress; i.e. resistance to flow

• Measured at constant temperature (40oC or 100oC)

Viscosity

ASTM D-445Constant Temp.Oil Bath40oC or 100oC

Nametre OscillationViscometerNon-ASTM TestAmbient Temp.

Emissions Spectrometer(ELEMENTAL SPECTROSCOPY)

EXCITATION SOURCE

SIGNAL PROCESSING

RDE

ICP

AA

LIGHT EMISSIONS

DETECTORS

DIFFRACTION

GRATING

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

• 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 Ferrograph

DR Acceptance LimitsWEAR PARTICLE CONCEN. ACCEPTANCE LIMITS

Vacuum Pumps WPC = 1-5Boiler Feed Pumps WPC = 1-100Gas CompressorsTurbinesFans

WPC = 1-50

Journal Bearings WPC = 1-20Roller Bearings WPC = 5-100EnginesTransmissions

WPC = 10-150

Extruder Gearboxes WPC = 100-600Dragline GearboxesHoist Gearboxes

WPC = 1,000-50,000

• View slide made by FM• Several magnifications

–Speed–Detail

• Identify debris using–Reflected light–Transmitted light–Polarized light–Color filtered light

Analytical Ferrography

BEARING WEAR

Low Alloy Steel

Steel Prior to Heat Treatment Lead/Tin Babbitt Metal

Copper Alloy

Particle Classification

•Size

•Shape

•Concentration

•Composition

Analytical Ferrography

Analytical Ferrography

Rating 1 Rating 2 Rating 3 Rating 4 Rating 5

Rating 6 Rating 7 Rating 8 Rating 9 Rating 10

Analytical Ferrography Correlation w/ DR FerrographCorrelation w/ DR Ferrograph

WPC=10 WPC=50 WPC=100 WPC=500 WPC=1000

Equipment Condition Report

Equipment Condition Report (cont)

YesYes• Detect Dissolved up to

8m Particles

• Determine Lubricant Additive Depletion

• Detect Fluid Contamination

• Determine Lube Physical Condition

No• Problems detecting Onset

of Abnormal Wear

• Determining Sources of Wear (bearings, gears, seals, rings, etc.)

• Reliable Estimate of Machine Wear Condition

SummarySummaryFirst Sample AnalysisFirst Sample Analysis

First Sample AnalysisFirst Sample Analysis• Observation i.e., water, large

particles

• Viscosity

• RDE Spectroscopy (21 metals)

Yes

Yes

Limited w/ Ref.

First Sample AnalysisFirst Sample Analysis• FT-IR Spectroscopy

• Water by Karl Fischer Titration

• TAN, TBN

• DR Ferrograph

• Analytical Ferrography

No

Yes

No

Limited

Yes

Questions