Machinery Lubrication

Machinery Lubrication Sept Oct 2015

Machinery Lubrication magazine published by Noria Corporation

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26 | September - October 2015 | Limit and warning levels from elemental spectrometric analysis serve as indicators of the amount of foreign particles found in used oil that is still tolerable or, when compared with fresh oil, indicate when the altered lubricant must be changed. Values well above toler- able wear levels can also indicate an acute damage process. However, it is not easy to specify these warning levels. Hardly any engine or equipment manufacturer defines limit levels for used oil. This is because the operating conditions and times are too specific, and the origins of the foreign parti- cles found in the oil are too diverse. Consequently, determining these factors is one of the essential tasks of every oil anal- ysis. After all, the type, quantity and (to a certain extent) the size of the particles provide valuable information about wear, contaminants and the additives in the oil. When warning and limit levels are used for the diagnosis of a specific oil specimen, the interactions between the values and other criteria should also be taken into By steffen Bots, oelcheck OIL ANALYSIS Establishing Elemental Limit Values for Motor Oils ELEMENT UPPER WARNING LEVEL ORIGIN Iron (Fe) 80–180 Cylinder block, cylinder head, timing wheels and timing chains, valves, valve tappets and guides, crankshaft, camshaft, rocker arm shaft, piston pins, roller bearings (with chromium), oil pump; rare in residues of ferrocene, a fuel additive for soot reduction; distinguishing between corrosion and wear based on the PQ index Chromium (Cr) 4–28 Piston rings, crankshaft bearings, piston pins, exhaust valves, gaskets, guide bushes, chrome-plated parts and gears; Fe, Al and Cr are usually found in combination with Si in engines because dust causes the most piston (Al), piston ring (Cr) and cylinder (Fe) wear Tin (Sn) 12–24 Often together with lead (Babbitt bearings) or copper; running surfaces of connecting-rod bearings, rocker arm shaft and piston pin bearings, solder (consisting of lead and tin) in soldered radiator joints; constituent of some synthetic base oils, additives in fire-resistant fluids Aluminum (Al) 12–55 Primarily from pistons, oil pump housings, oil coolers, torque converter parts, turbocharger, guide bushes, plain bearings, cylinder blocks of all-aluminum engines (together with silicon) and dust containing bauxite (aluminum oxide) Nickel (Ni) 1–3 Alloy constituent of exhaust valves, valve guides, turbochargers, high-strength gears and turbine blades; instead of being galva- nized or chrome-plated, parts such as filter components may be nickel-plated; constituent of heavy oil (together with vanadium) Copper (Cu) 25–60 Main constituent of brass and bronze; as wear metal from oil pumps, connecting-rod bearings, piston pin bearings, rocker arm shaft bearings, bronze worm gears, and sintered brake and clutch discs; resulting from the corrosion of oil coolers, piping and seals Lead (Pb) 10–30 Usually in combination with tin and/or copper; connecting-rod bearings, nearly all running surfaces of plain bearings and soldered joints in combination with tin Molybdenum (Mo) 4–20 Up to 500 in fresh oil Contained in transmission synchronizer rings, piston rings and heat-resistant steels; component of an antioxidant and friction modifier additive package in modern synthetic multigrade oils and gear oils; rarely as MoS2 oil additives Table 1. Wear elements

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