Sources of Wear Metals in Lube Oil Analysis

Sources of Wear Metals in Lube Oil Analysis

Iron (Fe)

Iron is the most common of the wear metals, present in some form in virtually all equipment. Its widespread presence means that there are many sources of wear particles. Because of this knowledge, the metallurgy of the component allows the analyst to distinguish the source of the wear debris , e.g. cast Iron bolts Vs Stainless steel lube oil piping.

Equipment	Wear Metal Sources
Engines	Most common of the wear metals. Engines : cylinder liners, piston Ring, valve train, crankshaft ,rocker arms, spring gears , lock washers, nuts  , pins, connecting rods engine blocks oil pump.
Bearings	Rolling element Bearings; rollers (tungsten alloyed steel), raceways and cages, journal bearings journal shaft.
Gears	Bull gears, Pinions , case hardened teeth  locking pins
Transmission	Gears, bearings, brake bands, clutch, shift spools, pumps power take off
Hydraulic system	Pump, motor, vanes, pump housing ,cylinder bores and rods servo valves, piston
Compressors	Rotary Screw lobes, vanes connecting rods, rocker arm bearings, cylinders, housing, shaft, roller bearings.
Turbines	Reduction  gear, shaft bearings piping ,case.

COPPER

Widely used as an alloying element , copper is prized because of its material properties – very ductile, and excellent thermal and electrical conductivity. It is heavy used in bearing systems, as well as heat exchangers.

Equipment	Wear Metal Source
Engines	Valve train bushing , wrist pin bushings , cam bushing , oil cooler core, thrust washers, governor, connecting rods bearings, valve gear, train thrust buttons
Bearing	Rolling  element Bearings : alloyed element in cages, journal bearings Journal bearing pads, slinger rings , locking key
Gears	Bushing , thrust washers
Transmission	Clutches , steering discs, bearing
Hydraulic  system	Pump thrust plate, bushing , cylinder gland guides, pump pistons , oil coolers
Heat Exchangers	Cooler tubes , baffles , plates
Compressor	Bearings , cylinder guides , wear plates, thrust washers , bearings , oil pump , oil coolers thermostats , separator filters
Turbines	Bearing , Piping , cooler

TIN (Sn)

Tin is used an alloying element with copper and lead for sacrificial bearing liners.

Equipment	Wear metal Source
Engines	Valve train bushing , wrist pin bushing , cam bushing , oil cooler core, thrust washers , governor , connecting rods bearings , valve gear train thrust buttons
Bearing	Rolling element bearing : alloyed element in cages , Journal Bearings : Journal bearing pads
Gears	Bushing
Transmissions	Clutches, steering , disc, bearing
Hydraulic System	Pump thrust plates, bushings, can be residue from catalyst in some oils
Compressive	Bearings, Separator filter
Turbines	Bearing , Piping , coolers

Aluminium (Al)

Aluminium is valued in equipment because of it high strength to weight ration, and excellent corrosion resistance, alloyed with other elements improves its wear and temperature resistance. It is widely specified for equipment manufacturing now a day.

Equipment	Wear metal Sources
Engines	Engine blocks, pistons, blowers, oil pump bushings, Cabushing , Oil coolers
Bearing	Rolling element bearing : alloyed element in cages, locking key
Gears	Bushing , thrust washers, grease contamination
Transmission	Bushings, clutches
Hydraulic system	Cylinder glands pump, motor pistons , oil coolers, aluminium complex grease contaminant.
Heat exchanges	Cooler tubes, baffles, plate
Compressor	Housing ,bearing, cylinder  guides, wear plate, thrust washers, bearing , oil pump , oil coolers
Turbines	Bearing , piping coolers EHC systems, residue from synthetic media

Chrome (Cr)

Chrome is used as an engineering material for its great hardness and corrosion resistance. It is found in many systems operating under harsh conditions.

Equipment	Wear metal Sources
Engines	Rings, liners, exhaust valves , zinc chromate from cooling system inhibitor
Bearings	Rolling element bearing: alloyed /coated element in rollers, tappers
Gears	Bearing , shaft coatings, some special gears are chrome plate
Transmissions	Bearing, water treatment
Hydraulic system	Cylinder liners , rods , spools
Heat exchangers	Cooler tubes , baffles , plates
Compressors	Housing bearings, cylinder guides , wear plates , thrust washers, bearing , oil pump , oil coolers
Turbines	Shaft coating bearing

 Lead (Pb)

A soft metal used for sacrificial wear surfaces such as journal bearings .lead based babbits are widely used.

Equipment	Wear Metal Sources
Engines	Main bearings, connecting rod bearings. Lead can be present as a contaminant from gasoline improver , anti - knock
Bearings	Rolling element bearing : alloyed element in cages, journal bearing : major alloying element in babbit bearings , alloying element
Gears	Bearing , can also be red lead paint flakes from gear case walls
Hydraulic System	Bearing
Compressor	Bearings
Turbines	Bearing

Silicon (Si)

Silicon is the most common contaminant found in lube oil analysis. Abundant in all areas send is a very hard crystalline material, and very abrasive to metal components.

Equipment	Wear metal source
Engines	Engines blocks , ingested dirt from breathers, external source , can also be from defoamant additive in lubricant.
Bearings	Rolling element bearings: alloyed element with aluminium an cages
Gears	Bushings, thrust washer, silicone sealant , defoamant  additive
Transmissions	Brake shoes , clutch plates ingested dirt
Hydraulic system	Elastomeric seals pump , motor pistons, oil coolers
Heat exchanger	Coolers tubes, baffles , plates
Compressors	Ingested dirt, silicon sealant , bearings , cooler
Turbines	Ingested dirt, silicone sealant  defoamant additive

Silver (Ag)

Silver has exceptional thermal conductivity, and is an excellent bearing plate material , providing minimum friction . It is susceptive to corrosive attack by zinc – based additives,and so railroads ensure that they receive zinc free oil if they run EMD locomotives, Silver is used more outside of the US in general industrial equipment

Equipment	Wear metal source
Engines	Valves, valve liner , cylinder liner bearings
Bearings	Rolling element bearings : alloyed element in rollersa , raes
Gears	Alloying element for tool steel gears
Hydraulic system	Bearings, servo valve plating pumps
Compressor	Bearings
Turbines	Bearings, shaft , reduction gears

Metallic additives

Several other elements are detected with oil analysis. The major elements found are listed here:

Element	Possible Sources
Sodium	Corrosion, inhibitor additive, also indicates coolant leak into oil, can be road salt, sea water, ingested dirt.
Boron	Corrosion inhibitor additive, anti wear/antioxidant additive ,can indicate coolant leak , grease contamination
Magnesium	Detergent/dispersant additive can also be alloying element in steel
Calcium	Detergent/dispersant additive, alkaline , reserve additive, for high sulphur fuelled engines , can be grease contamination
Molybdenum	Solid /liquid anti wear additive, alloy in bearing and piston
Barium	Corrosion inhibitors , detergents ,rust inhibitor
Zinc	Anti wear, corrosion inhibitors , anti – oxidants , alloying element for bearings , thrust washer galvanized cases
Phosphorus	Anti wear , corrosion inhibitors, anti – oxidants additive , EP additive