Grease basic knowledge_nk0906

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  • 1. HOME END Fuchs Indonesia Fuchs Indonesia 1

2. HOME END Fuchs Indonesia Grease A solid to semi-fluid product of a thickening agent in a liquid lubricant.Other ingredients imparting generalproperties may be included 2 3. HOME ENDFuchs IndonesiaGrease Advantages DisadvantagesConvenienceLow Cooling RateResistance ContaminationProtection PerformanceCleanlinessLimitations 3 4. HOME ENDFuchs Indonesia Grease Composition Base Oil Thickener Additives 70 - 95%10 - 20%5 - 10% Grease 4 5. HOME ENDFuchs IndonesiaLubricating Greases - Basics and Applications 5 6. HOME ENDFuchs IndonesiaComponents Used in Grease FormulationBase oilsThickeners AdditivesMineral oils Sodium soapAnti-oxidantsSynthetic mineral oils Calcium soap Anti-wear additivesDi-estersLithium soap EP additivesSiliconesAluminium soap Corrosion inhibitorsPhospate estersBarium soapFriction modifiersFluorocarbon Aluminium complexMetal deactivatorsFluorinated silicone Lithium complexVI improversChlorinated silicone Bentonite clay Pour-point depressants Silica Tackiness additives Carbon/graphiteWater repellants Polyurea Dyes PTFE Structure modifiers Polyethylene Indanthrene dye Phthalocyanine dye 6 7. HOME END Fuchs Indonesia Typical Oils Used in Lubricating Greases Petroleum Paraffinic good VI and thermal stability to 350oF max. temp. Naphthenic good low temperature performance to 65oF min Synthetic Nominal Serviceable Temp. Range. oF Diester - 100 to 400 Fluorosilicone- 50 to 450 Hydrocarbon - 80 to 350 Polyalkylene glycol - 40 to 350 Polyol ester- 50 to 400 Silicone- 100 to 450 7 8. HOME END Fuchs IndonesiaBase Oil For GreaseDepends on required characteristics of grease. Flow, viscosity, temp. range and speed.Paraffinic and napthenic mineral oilsSynthetics used for special applications very low/very high temp.Base oil function is to lubricate8 9. HOME END Fuchs Indonesia Thickener Types Metal soaps Lithium, calcium, sodium, barium, aluminium, etc Complex (I.e. Lithium complex, alumunium complex, Calcium complex) Inorganics/non soap Clays, megalite, montmorilonite, hectorites, bentonites Organics Polyurea Fluoro Organic PTFE9 10. HOME ENDFuchs Indonesia Thickener Influences Act as a carrier To release fluid Water Resistance 1. Washout Resistance - the ability of the lubricant to stay in the bearingwhile operating partially or fully submerged (ASTM D1264). 2. Water Absorption - the ability of the grease to deal with the presence ofwater by either absorbing or resisting the washing and diluting action ofthe water. 3. Spray Resistance - the ability of the grease to resist displacement from adirect impingement of the water on the greased surface (ASTM D4049). Heat Resistance 10 11. HOME ENDFuchs IndonesiaGrease Additives Anti-Wear/Extreme Pressure Agents Zinc dialkyIdithiophosphates Dithiocarbamates (Zn, Sb, Pb) Phosphate esters Sulfurized fatty acids Sulfurized hydrocarbons Chlorinated hydrocarbons11 12. HOME END Fuchs Indonesia Grease Additives Anti-oxidants Aryl amines Zinc dialkyldithiophosphates Hinderes phenols Zinc and amine dithiocarbamates12 13. HOME ENDFuchs IndonesiaGrease Additives Rust and Corrosion Inhibitors Sulfonates (Ca, Ba, Li, Mg, Na, Pb, amine salts) Napthenates (Zn, Ba, Pb) Carboxylic acid derivatives Triazoles Sodium Nitrite13 14. HOME END Fuchs IndonesiaGrease Additives Friction Modifiers Molybdenum disulfide Graphite PTFE Powdered fluorocarbons14 15. HOME END Fuchs Indonesia Grease Additives Adhesion Promoters Polyolefins and olefin copolymers15 16. HOME ENDFuchs Indonesia PenetrationThe depth, in tenths of a millimeter, that a standard cone sinks into amaterial under prescribed conditions of weight, time and temperature.This depth is described as NLGI numbers. NLGI NumberASTM Worked Penetration 000 445-475 00400-430 0 355-385 1 310-340 2 265-295 3 220-250 4 175-205 5 130-160 685-115 16 17. HOME END Fuchs Indonesia Factors In Deciding NLGI Grades Speed The higher the speed the harder the grease, so for high speeds use no. 3. The maximum outer race speed for grease- lubricated rolling bearings is about 15 m/s (3000 ft/min) Bearing size Use a harder grease in a large bearing, No.3 or even no.4 Sealing If there is a particular need for effective sealing, use a harder grease, No.3 or No.417 18. HOME END Fuchs Indonesia Factors In Deciding NLGI Grades Shock loads or vibration Shock load or vibration tends to cause grease to slump into the moving components causing churning. A harder grease minimizes the problem, so use No.3 or No.4. (Note that normal steady loading does not strongly influence the grade) Temperature18 19. HOME ENDFuchs IndonesiaGrease SelectionSome basic rules:Low speeds Greases with high base oil viscosityand high loads and EP and / or solid lubricants like Graphite or MoS2High speedsGreases with low base oil viscosityOscill. movement Greases with white solid lubricantsHigh or lowGreases with synthetic base oilstemperatures19 20. HOME END Fuchs Indonesia Important factors on Grease selection1. Bearing design2. Bearing speed3. Load4. Temperature5. Environmental conditions20 21. HOME END Fuchs IndonesiaGrease Incompatibility 21 22. HOME END Fuchs IndonesiaBase fluid compatibilityMinerall Polyalfa- Poly-Ester, Natives l Alkoxy- Silikonl l-olefinglykol synth.fluorl Typ Minerall ++ -+ + - - Polyalfa- olefin++ -+ + - - Polyglykol - -+ --- - Ester, synth.++ -+ + - - Natives l++ -+ + - - Alkoxy- fluorl- - --- +- Silikonl- - ---- + 22 23. HOME END Fuchs Indonesia Calculation of lubricant consumptionEffective lubrication is the combination of a suitablelubricant, right re-lubrication intervals and the optimum re-lubrication quantity.The more, the better is (nearly) always wrong. Over-lubrication leads to preliminary bearing failure and causesadditional costs.Frequent re-lubrication with small quantities is better thanseldom re-lubrication in huge quantities. Optimization isnecessary, because frequent re-lubrication needs moretime. 23 24. HOME ENDFuchs IndonesiaCalculation of lubricant consumption: When calculating the optimum grease quantity, the free volume in the bearing as well as free space in the housing has to be considered. First fill of bearing: Fill the bearing completely, fill free space in the housing only with a quantity which allows, that grease coming out of the bearing during operation can remain in the housing to avoid undesired heating of the grease and the bearing. Sometimes sealing discs can be helpful. 24 25. HOME END Fuchs Indonesia Calculation of lubricant consumptionExceptions:very high speeds: fill bearing and housing only to one third to avoidineffective working of the greasevery low speeds: fill bearing and housing completely to ensurelubrication of all parts. In this case inner friction of thegrease can be neglected. 25 26. HOME END Fuchs Indonesia Calculation of lubricant consumptionCalculation of the free bearing volume:Calculation can be done with the dimensions and weightsgiven by the suppliers of the bearings with the followingformula: V /4 . B . (D - d) . 10-3 - G . 1000 / 7,8 [cm]V - free bearing volume in cm d - Inner diameter in mmB - Bearing width in mmG - Weight in kgD - Outer diameter in mm26 27. HOME ENDFuchs Indonesia Calculation of lubricant consumptionBasic quantities when using grease guns:One stroke with aconventional (DIN) orwithSYSTEM REINER-Grease Gun gives ca. 1,5- 2 ccm of grease.27 28. HOME END Fuchs Indonesia Calculation of lubricant consumption Re-lubrication quantities and -intervals depend very much on the real operating conditions. Therefore, exact calculation is extremely difficult. In the past data of practical applications were collected which were used as a data base for calculations for specific application fields. These calculations use factors for special operating conditions which were found by studying numerous similar applications. Difficulties arise from the determination of these correction factors as well as from the use of specialised greases with a performance being much higher than that of conventional Li-soap-mineral-oil greases.28 29. HOME ENDFuchs Indonesia Calculation of lubricant consumption Correction factors for re-lubrication intervals f1 - Dust and moisture (0.1 ... 0.9) f2 - Shocks, vibrations(0.1 ... 0.9) f3 - Temperature higher than 70C(0.1 ... 0.9) f4 - High load (0.1 ... 1.0) f5 - Air flow through the bearing(0.1 ... 0.7) The reduced re-lubrication interval is then calculated by multiplying all these single factors: tfq = f1 . f2 . f3 . f4 . f5 . tf29 30. HOME ENDFuchs IndonesiaASTM Grease Tests 30 31. HOME END Fuchs IndonesiaMechanical dynamic testing of lubricating greasesFE 8-bearingsTimken-machine with specimen FBT-ballsEmcor-machines31 32. HOME END Fuchs Indonesia ClassificationLubricating GreasesProperties:Consistency (NLGI-grade)Temperature rangeEP-properties Classification (DIN 51502):Base oil viscosity and typee.g. K P F 2 K -20ThickenerSolid lubricants32 33. HOME ENDFuchs Indonesia Grease Troubleshooting GuideApplication SymptomPossible CauseCheck ForBearings RollingNoiseCondition of bearingWorn or brinelled bearingcontactHigh bearing temp. Over greasing Too frequent application Bearing packed too full Excessive grease charge StarvationInsufficient application frequency Incorrect product Wrong base oil viscosityExcessive leakageSeals Mechanical damage Incorrect installation Over greasing Too frequent application Excessive amount applied Incorrect product Too soft for application or softening in service Incompatibility of grease Admixture of grease 33 34. HOME END Fuchs IndonesiaGrease Troubleshooting GuideApplication SymptomPossible CauseCheck ForBearings RollingFrequent bearing Excessive wearDeficient load carrying (EP)contact replacement Starvation Contamination (dirt,dust) Bearing life exceeded Improper installation Grease too stiff (channeling) High temperatureHigh operating temperature MisalignmentCorrect