SCOUT CAR GUIDE
1 INTRODUCTION TO ENGINEERING TRIBOLOGY 2 PROPERTIES AND CHARACTERISTICS OF TRIBO SURFACES 33 3 CHARACTERIZATION OF SOLID SURFACES IN CONTACT 76 4 FRICTION AND WEAR 125 5 TRIBOLOGY OF METALS AND ALLOYS 205 6 TRIBOLOGY OF NONMETALS 233 7 LUBRICATION AND SURFACE ENGINEERING 293 8 LUBRICANTS AND THEIR PROPERTIES 342 9 TRIBOLOGY TESTING MEASUREMENTS AND EVALUATION 387 10 PRACTICAL APPLICATIONS OF TRIBOLOGY 450 CONTENTS INTRODUCTION TO ENGINEERING TRIBOLOGY 1 1 1 INTRODUCTION ALTHOUGH TRIBOLOGY IS AN UNFAMILIAR TERM FOR MANY AND A NEW ELD OF SCIENCE FOR SOME UNDOUBTEDLY IT IS EXPERIENCED BY ALL IN FACT IN OUR DAILY LIVES WE DEAL WITH NUMEROUS TRIBOLOGICAL APPLICATIONS EXAMPLES WRITING WITH A PENCIL ON PAPER CLEANING A SURFACE WITH A BRUSH USING A NAIL LE USING AN OIL TO STOP SQUEAKY DOOR HINGES AND OTHERS THE SCIENCE OF TRIBOLOGY IS THEREFORE BASICALLY DEALING WITH CONTACTING SOLID SUR FACES IN RELATIVE MOTION AND IT CONSISTS OF THREE BRANCHES FRICTION WEAR AND LUBRICA TION IT CONSEQUENTLY HAS A WIDE RANGE OF APPLICATIONS ACROSS MANY INDUSTRIES INCLUDING MANUFACTURING TRANSPORT MEDICINE SPACE AND OTHERS EVEN THOUGH THE WORD TRIBOLOGY CHARACTERIZES PHENOMENA AND PROBLEMS THAT AROSE SINCE THE STONE AGE AND EXTEND TO OUR PRESENT LIVES THE WORD ITSELF WAS RST INTRODUCED IN THE LAST CENTURY BY DR H PETER JOST AND HIS RESEARCH GROUP IN FEBRUARY 1966 THEY PROPOSED FOR THE RST TIME THE WORD TRIBOLOGY TO DESCRIBE THIS ELD OF SCIENCE JOST 1966 THE WORD CONSISTS OF TWO TERMS CLASSIC GREEK TRIBO MEANING RUBBING AND THE SUF X LOGY FOR THE KNOWLEDGE OF SO THE LITERAL TRANSLATION WOULD BE THE SCIENCE OF RUBBING PRESENTLY TRIBOLOGY A NEW ELD OF SCIENCE IS DE NED IN MANY DICTIONARIES AS THE SCIENCE OF INTERACTING SURFACES IN RELATIVE MOTION OR THE STUDY OF FRICTION WEAR AND LUBRICATION AND THE DESIGN OF BEARINGS DICTIONARY OXFORD FIG 1 1 REPRESENTS AN ILLUSTRATION OF THE TRIBOLOGY TRIANGLE TYPICALLY THE INTERACTION OF SOLID SURFACES IS HIGHLY COMPLEX AND KNOWLEDGE OF VARIOUS DISCIPLINES AND ELDS IS REQUIRED THESE MAY INCLUDE BUT ARE NOT LIMITED TO PHYSICS CHEMISTRY APPLIED MATHEMATICS SOLID MECHANICS UID MECHANICS THERMODY NAMICS HEAT TRANSFER MATERIALS SCIENCE RHEOLOGY LUBRICATION MACHINE DESIGN FIGURE 1 1 TRIBOLOGY TRIANGLE 1 PERFORMANCE AND RELIABILITY FURTHERMORE THERE IS A FURTHER COMPLEXITY DUE TO THAT TRIBOLOGY IS STRONGLY ASSOCIATED WITH A WIDE RANGE OF PRACTICAL APPLICATIONS WITH SMALL POSSIBILITIES OF THE THEORETICAL FORMULATION FOR A LIMITED RANGE OF THEM IF WE TRY TO EXPLORE THE PRINCIPAL CONSTITUENTS OF TRIBOLOGY OF INTERACTING SOLID SURFACES WE REALIZE THAT FRICTION AND WEAR ARE VERY ANCIENT ONES 1 1 1 FRICTION FRICTION IS A NATURAL PHENOMENON THAT PLAYS A GREAT ROLE IN OUR DAILY LIVES DEPENDING ON SERVICE CONDITIONS EITHER HIGH OR LOW FRICTION MAY BE REQUIRED NEVERTHELESS IN TRIBOLOGY STUDIES FRICTION IS NORMALLY CONSIDERED THE MAJOR CAUSE OF WEAR AND ENERGY LOSS OF THE SLIDING SYSTEM THE WORD WAS RST USED IN THE 16TH CENTURY IS DERIVED FROM LATIN FRICTIO MEANING A CHA NG OR RUBBING AND FROM MIDDLE FRENCH FRICTION AS A NOUN OF ACTION FROM PAST PARTICIPLE STEM OF FRICARE MEANING TO RUB IT IS RECORDED THAT THE RST USE OF THE WORD FRICTION TO DESCRIBE RESISTANCE TO MOTION WAS IN THE 17TH CENTURY DICTIONARY OXFORD VARIOUS DE NITIONS WERE INTRODUCED TO DESCRIBE THE PHENOMENON HOWEVER MOST OF THEM SUGGEST THAT THERE ARE TWO REGIMES OF FRIC TION 1 STATIC FRICTION PRIOR TO THE INITIATION OF THE RELATIVE MOVEMENT BETWEEN TWO SOLID SURFACES AND 2 KINETIC OR DYNAMIC FRICTION OCCURRING BETWEEN TWO MOVING SUR FACES TO SIMPLY DISTINGUISH BETWEEN THE TWO CASES IN STATIC FRICTION THE FORCE GENER ATED BETWEEN THE TWO SOLID SURFACES IS SUF CIENT TO RESIST THE MOTION WHEREAS IN DYNAMIC FRICTION IT IS INSUF CIENT IN BOTH REGIMES FRICTION IS EXPRESSED IN QUANTITA TIVE TERMS AS THE FORCE GENERATED BETWEEN THE TWO SOLID SURFACES IN THE DIRECTION OPPO SITE TO THE DIRECTION OF RELATIVE MOVEMENT FOR KINETIC FRICTION OR POTENTIAL MOVEMENT FOR STATIC FRICTION 1 1 2 WEAR WEAR IS CONSIDERED THE FOREMOST CAUSE OF MATERIAL WASTAGE AND OR SURFACE DEFORMATION WHICH CAN EVENTUALLY LEAD TO THE FAILURE OF MECHANICAL COMPONENTS THE WORD WEAR WAS USED IN THE LATE 13TH CENTURY WITH CLOTHING TO EXPRESS THEIR GRADUAL DETERIORATION DUE TO CONTINUED USE IN TRIBOLOGY WEAR IS ASSOCIATED WITH THE DEFORMATION AND GRADUAL REMOVAL OF MATERIAL ON A SOLID SURFACE AS A RESULT OF THE MECHANICAL AND CHEMICAL AC TIONS OF THE COUNTERPART SURFACE AMERICAN SOCIETY FOR TESTING AND MATERIALS 2001 AMONG SEVERAL EXPRESSIONS OF THIS PROCESS WEAR CAN BE DE NED AS PROGRESSIVE LOSS OF SUBSTANCE FROM THE OPERATING SURFACE OF A BODY OCCURRING AS A RESULT OF RELATIVE MO TION AT THE SURFACE HALLING 1979 ORGANISATION FOR ECONOMIC CO OPERATION AND DEVELOPMENT RESEARCH GROUP ON WEAR OF ENGINEERING MATERIALS 1969 RABINOWICZ 1995 DEPENDING ON SURFACE PROPERTIES AND OPERATION CONDITIONS DIFFERENT WEAR MECHANISM S MAY PREVAIL IN THE CONTACT BODIES SUCH AS ADHESIVE ABRASIVE SURFACE FA TIGUE IMPACT FRETTING EROSION AND CORROSION WEAR FROM THE ENGINEERING POINT OF VIEW WEAR IS GENERALLY THOUGHT OF AS AN UNDESIRABLE PHENOMENON WHICH CAN BE INDEED FOUND IN THE MAJORITY OF PRACTICAL CASES HOWEVER THIS IS NOT ALWAYS TRUE IN FACT THERE ARE A CONSIDERABLE NUMBER OF USEFUL APPLICATIONS OF THE WEAR PROCESS FOR INSTANCE SUR FACE PRODUCTION AND SURFACE NISHING OF MANUFACTURED OBJECTS USING ABRASION SCOUT CAR M3A1 2 PROCESSES AND THE USE OF A PENCIL OR CHALK ARE EXAMPLES OF DESIRABLE WEAR THUS PRAC TICALLY WEAR IS NOT ALWAYS TO BE AVOIDED SINCE TIME IMMEMORIAL EFFORTS HAVE BEEN DONE TO IMPROVE THE SMOOTHNESS OF THE MOTION OF AN OBJECT OVER A SURFACE AS WELL AS TO MINIMIZE WEAR AND CONTROL FRICTION THIS TRIGGERS THE NEED FOR INTERPOSING A SUBSTANCE UID OR SOLID LM TO REDUCE THE CONTACT BETWEEN MOVING SURFACES 1 1 3 LUBRICATION LUBRICATION IS AN EFFECTIVE MEANS TO REDUCE FRICTION AND PREVENT OR CONTROL WEAR THE RST RECORD OF USING THE WORD WAS IN THE EARLY 19TH CENTURY FROM LATIN LUBRICATUS PAST PARTICIPLE OF LUBRICARE MEANS TO MAKE SLIPPERY DICTIONARY OXFORD SINCE LUBRICA TION CAN EFFECTIVELY CHANGE THE PERFORMANCE OF TRIBO SYSTEMS ANY SYSTEM CONTAINING TRIBOLOGICAL COMPONENTS ONE OF THE MOST GENERAL DE NITIONS IS THAT A LUBRICANT IS A SUBSTANCE CAPABLE OF ALTERING THE NATURE OF THE SURFACE INTERACTION BETWEEN CONTACTING SOLIDS WE WOULD EMPHASIZE HERE THAT THE TERM SUBSTANCE IN THE PREVIOUS DE NITION IS NOT SIMPLY EXCLUSIVE TO LIQUID OILS AS IT MAY BE THOUGHT OF EVEN THOUGH THEY ARE WIDELY USED AS LUBRICANTS IN MANY APPLICATIONS THERE ARE OTHER CONDITIONS OF LUBRICA TION SUCH AS UID LUBRICATION GREASE SOLID LUBRICATION AND AIR AND GAS LUBRICATION ANY UID INCLUDING WATER CAN BE USED AS A UID LUBRICANT IN THE PROPER APPLICATION IN UID LUBRICATION THE LUBRICATION REGIME IS CONSIDERED ACCORDING TO THE CONDITION OF THE LUBRICANT INTRODUCED INTO A SLIDING SYSTEM THE THREE DISTINCT LUBRICATION REGIMES ARE UID LM LUBRICATION BOUNDARY LUBRICATION AND MIXED LUBRICATION THE MOST IMPORTANT PROPERTY OF THE LUBRICANT IN UID LUBRICATION IS THE VISCOSITY OF THE LUBRICANT GREASE IS A STABILIZED MIXTURE OF A LIQUID LUBRICANT MINERAL OR SYNTHETIC UID AND A THICKENING AGENT SOME ADDITIVES MAY BE INTRODUCED TO ADD PARTICULAR PROPERTIES SOLID LUBRICATION IS INTRODUCING A SOFT SOLID LM BETWEEN SLIDING SURFACES ALSO IT MAY BE FOUND AS A RESULT OF A CHEMICAL REACTION BETWEEN THE SLIDING SURFACE AND ITS ENVIRON MENT AIR OR GAS IS NOW A QUITE COMMON LUBRICANT IN HIGH SPEED BEARING APPLICATIONS FOR ALL PREVIOUS KINDS OF LUBRICATION THE MAIN TASK IS TO REDUCE FRICTION WEAR AND SUR FACE ADHESION IN OTHER CASES LUBRICATION IS INTRODUCED IN TRIBO SYSTEMS TO CONTROL THE INTERFACIAL TEMPERATURE WHEN LUBRICATION BREAKS DOWN SOLID SURFACES OF ENGINEERING COMPONENTS CAN RUB AGAINST EACH OTHER RESULTING IN HIGH FRICTION AND HEAT THIS CAN CAUSE SURFACE DAMAGES SUCH AS LOCAL WELDING MATERIAL REMOVAL OR TRANSFERRING AND NALLY THE FAILURE OF THE SYSTEM 1 2 HISTORICAL BACKGROUND THE EXISTENCE OF TRIBOLOGY CONSTITUENTS IS AS OLD AS THE BEGINNING OF HUMANKIND S HIS TORY THERE ARE MANY WELL DOCUMENTED EXAMPLES OF HOW THE RST MAN USED TRIBOLOGY CONCEPTS TO FACILITATE HIS DAILY ACTIVITIES PROBABLY THE EARLIEST TRIBOLOGICAL APPLICATION IN THE PALEOLITHIC PERIOD WAS THE USE OF THE FRICTION PHENOMENON IN LIGHTING RES BY RAPIDLY GRINDING PIECES OF WOOD AGAINST A HARD SURFACE THERE IS EVIDENCE THAT CONCEPTS SCOUT CAR M3A1 3 OF FRICTION AND WEAR WERE USED IN DEVELOPING TOOLS WEAPONS AND CONSTRUCTION FOR EXAMPLE THERE IS SOME INDICATION THAT NATURAL BITUMEN WAS USED AS A LUBRICANT IN WHEEL BEARINGS 5000 YEARS AGO IN EGYPT RECORDS BACK TO THE MIDDLE OF THE MESOLITHIC PERIOD SHOW THE USE OF STUDDED WHEELS AND BEARINGS FOR STONE POTTERS WHEELS TO REDUCE FRIC TION IN TRANSLATIONAL MOTION FIG 1 2 ALSO ARTWORK FROM THE TOMB OF DJEHUTIHOTEP AT EL BERSHEH 1800 B C ADVOCATES THAT ANCIENT EGYPTIANS WERE THE EARLIEST PIONEERS IN USING LUBRICANTS IN THE TRANSPORTA TION OF LARGE STONE BUILDING BLOCKS AND MONUMENTS AS SHOWN IN FIG 1 3 THE ILLUSTRA TION DEPICTS THE USE OF A SLEDGE TO TRANSPORT A HEAVY COLOSSAL STATUE OF THE MIDDLE KINGDOM WHICH CAN BE WEIGHTED UP 600 KN IN THIS TRANSPORTATION SLAVES DRAGGED THIS MASSIVE STATUE OVER WOOD PLANKS A CLOSER INVESTIGATION OF THE GURE SHOWS A MAN STANDING IN FRONT OF THE PEDESTAL OFTEN REFERRED TO AS THE RST TRIBOLOGIST POURING A LIQUID MAYBE WATER OR OIL FROM A JAR ONTO THE GROUND AHEAD OF THE SLEDGE BHUSHAN 2013 DOWSON 1998 ASSUMED THAT EACH SLAVE CAN PULL ABOUT 800 N CONSEQUENTLY THE TOTAL PULLING FORCE REQUIRED TO MOVE THE STATUE SHOULD BE NO LESS THAN THE FRICTION FORCE THIS WOULD SUGGEST A COEF CIENT OF FRICTION OF ABOUT 0 23 WHICH IS COMPARABLE TO THE LUBRICATED SLIDING OF WOOD ORGANIC LUBRICANTS WERE ALSO IMPLEMENTED IN THE SAME PERIOD WHERE A CHARIOT IN AN EGYPTIAN TOMB STILL CONTAINS SOME ANIMAL FAT LUBRICANTS IN WHEEL BEARINGS INTEREST INGLY IT WAS FOUND THAT THE LUBRICANT HAS BEEN USED AND WAS CONTAMINATED WITH ROAD DIRT IN THE FORM OF QUARTZ COMPOUNDS OF ALUMINUM IRON AND LIME HALLING 1979 TRIBOLOGISTS OFTEN CONSIDER THAT THE WHEEL IS ONE OF THE MOST IMPORTANT INNOVATIONS WITH THE TRANSITION FROM WOOD SLEDGES TO WHEELED TRANSPORT RST DISCOVERED IN ABOUT 3500 B C THE REMAINS OF MANY WHEELS DATING BACK TO THE THIRD MILLENNIUM HAVE FIGURE 1 2 WOODEN BEARING FOR STONE WHEELS ANCIENT EGYPT SCOUT CAR M3A1 4