GP Hyd Pump

nullApplied Failure Analysis for Parts Re-use TrainingApplied Failure Analysis for Parts Re-use Training General Procedures GuidelinesGeneral ProceduresGeneral ProceduresGeneral disassembly practices Parts marking - Standardized procedure Cleaning Visual exam Tooling Protecting parts before re-useParts Reuse PracticesParts Reuse Practices Get Organized - Need for Speed Think safety - Parts need protection too Know the customer - if not, error to the conservative Remove and install components - carefully Observe general condition - look at the whole picture Component disassembly - mark parts, handle with care Initial inspection - during disassembly Parts cleaning - beware of handling damage Visual inspection - Time = Money Protect parts for re-use - clean and dry storageGet OrganizedGet OrganizedGet organized before starting the job think through the process to be performed review manuals, become familiar with sequence have the tools needed for the job, organized use the special equipment required, it protects the parts and personnel are the facilities adequate to perform the work, especially important in field service will additional help be necessary and available when needed Think SafetyThink SafetyThink about safety for yourself and anyone helping you use chock, blocks, jack stands, and other safety equipment carelessness can disable and/or kill all other personnel in the repair area if you make a mess, clean it up immediately mark off work area if required machine and components determine the extent of the damage before starting, moving or operating the equipment don’t create more damage than already existsKnow the CustomerKnow the CustomerKnowledge of the customer application, operation, and maintenance history can help identify parts, components, or assemblies that may require closer examination. Document vehicle condition before repairTake SOS SamplesTake SOS SamplesTake SOS fluid samples at operating temperature before draining and removing or disassembling the component, the results can: indicate the operating environments that were present help determine which parts require closer examination e.g. bearings, bushings, clutch packs, etc identify parts that may have been overlooked ie. oil coolers, or heat exchangers for leaks Cut filters apart and inspect them for debrisRemove the ComponentRemove the ComponentUse proper lift, move, and support equipment spreader bars prevent flexing, bending, and broken parts movable lift point allows the component to be held at the correct angle, avoids binding, and sudden movement from shifting weight proper jacks, stands, and lifts provide good supportRight WayWrong WayRemove the ComponentRemove the Componentnever use the component fasteners to lift or support the component if fastener re-use is intended, especially critical fasteners such as head bolts, etc. support the component being removed before disassembling the fasteners to prevent bent parts or dropped components support equipment should carry only the weight of the component being removed to avoid binding prying components apart with screwdrivers or bars can damage gasket or mating surfaces , use jacking boltsObserve General Condition of the ComponentObserve General Condition of the ComponentLook for obvious problems that would prevent re-use of the various parts in the component Record anything abnormal, such as leaking seals or foreign material deposits, so the cause can be determined and corrected during re-assembly Look for wear types, locations, and patterns seven types of wear are commonly encountered each wear type has a characteristic appearance each wear type indicates a specific environment was present during operation and that other problems may exist location and pattern tell how and where loading was applied, may also indicate misalignment or bent partsWear Types and CharacteristicsWear Types and Characteristicsabrasive wear = scratches on part surfaces adhesive wear = melted and smeared metal on wear surface corrosion = oxidized metal and pits erosion = tiny impact dents and surfaces wearing away cavitation = localized sharp pitting where liquid is normally present contact stress fatigue = cracks and pitting in high load areas fretting = micro-welding and metal transfer on joint surfacesAbrasive WearAbrasive WearAbrasive wear occurs when hard particles get between two moving surfaces. Soft surfaces are cut leaving scratches, hard surfaces are not cut easily, but the rubbing action can create heat. Lubrication usually removes the heat generated. first determine what the particle is, this will aid in determining where it came fromAbrasive ScratchesnullnullAdhesive WearAdhesive WearAdhesive wear occurs when two moving surfaces make contact without adequate lubrication and/or cooling. Friction raises the surface temperature until melting and adhesion takes place. Early stages appear polished, more advanced stages become rough. why was there metal to metal contact, lack of lube or cooling problemsEarly StagesAdvanced StagesnullnullnullCorrosionCorrosionCorrosion is an electrochemical reaction where anodes (more active metal areas) give themselves up to cathodes (less active metal areas). An electrolyte, such as water, must be present to complete the circuit. Anodes move to the electrolyte, mix with oxygen and form an oxide. The removal of anodes creates pits. what is the electrolyte and how did it get to the partCorrosion & PitsErosionErosionErosion occurs when small hard particles hit part surfaces at high speeds causing impact and abrasive wear. Affected surfaces often have a shot peened or matte appearance. what are the particles and where are they coming from, is there a filtration problemImpact & Abrasive WearCavitationCavitationCavitation is a type of erosion caused by vapor bubbles in a liquid collapsing against a metal surface as the fluid pressures change from low to high. When the bubbles collapse, the fluid impacts the metal at supersonic speeds cracking and breaking small pieces of metal away. The damage is usually confined to a specific area. why are there air or vapor bubbles in the fluid? Cavitation ErosionContact Stress FatigueContact Stress FatigueContact stress fatigue occurs when two surfaces slide or roll against each other developing high stress, surface movements and fatigue cracks in one or both surfaces. As the damage advances, pitting and spalling occur. Damage is located in the high load areas and indicates too much load, concentrated loading, lube problems, etc. check lube quality, load, alignmentCracks & PitsSpallingFrettingFrettingFretting and fretting corrosion occur when two parts that normally fit tightly together are forced to move against each other slightly. The repeated movement causes micro welding of the small irregularities on the joined surfaces. Micro welding causes small pieces of metal to pull out leaving pits on one part and metal build-up on the other. The small pieces of steel can corrode leaving a reddish-brown oxide. check loading, fastener torque, clamping area, surface parallelism Pits & CorrosionWear Location & PatternWear Location & PatternWear location and pattern indicate how loading was applied to the parts Wear is usually centered and evenly distributed on the part contact surface if the wear is off center, at one end of a part or wanders, it could mean alignment, bent parts or loose fit problems exist in the componentLight Contact Heavy WearMisaligned GearsWear on Opposite SidesBent Con RodWear Type, Patterns and DebrisWear Type, Patterns and DebrisWear can create stress raisers that lead to failures Any type of wear, wear pattern or debris that is not considered “normal” for the application and/or hours should be investigated Determine the reason (root cause) for the particular wear type and pattern, refer to Applied Failure Analysis (AFA) materials Correct the cause during the re-assemblynullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullComponent Disassembly Component Disassembly Marking parts is critical for visual exam and re-use because it provides: timing location orientation family grouping Best to mark parts before and during disassemblyComponent DisassemblyComponent DisassemblyVarious methods may be used to mark parts acid pen vibrating pen scribe paint pen permanent marker Areas to be marked may need to be cleaned first Marks should not be removed during cleaning Always mark in areas that will not damage parts and marks will not wear awayComponent DisassemblyComponent DisassemblyAvoid using a hammer or impact tools that could damage parts during disassembly or re-assembly if re-use is intended damage to bearing will shorten service life damage to housing bore affects the bearing seating and roundness (egg shaped bearing race)Bearing Race DentHousing DamageComponent DisassemblyComponent DisassemblyParts Marking - Standardized ProcedureParts Marking - Standardized ProcedureParts marking procedure should be performed during disassembly to avoid forgetting or mixing parts with other rebuilds in progress Parts that are not salvageable should also be marked for reference during failure analysis, especially if being kept as an example for training purposes 9U7377 acid etching pen is an effective permanent marking instrumentParts Marking - Standardized ProcedureParts Marking - Standardized ProcedureIf instruments such as vibrating pens are used to mark parts, mark in areas of low stress concentration to reduce the possibility of induced failure Use SEBF8187-01 “Standardized Parts Marking Procedure” for more details on recommended areas to mark partsInitial InspectionInitial InspectionVisual examination is a continuous process performed during disassembly, cleaning, and re-assembly Initial inspection is performed during disassembly and should include: recording part numbers and manufacturers logo manufacturing and/or re-manufacturing date codes identifying marks such as supplier codes, forging die codes, steel heat codes, etc number of rebuilds and hours accumulated on each part looking at all areas of each part, paying special attention to high stress areas and normal stress raisers to determine if closer inspection is neededInitial InspectionInitial InspectionCheck and record all part number and manufactures logo to assure they are correct, up to date, and genuine Cat parts, remember that competitors can use Cat part numbers but not the logoCompetitor PartInitial InspectionInitial InspectionDate codes are forged or stamped on many new parts, and stamped, engraved or acid etched on remanufactured parts indicating the date of manufacture or remanufacture using the NUMERAL KOD systemInitial InspectionInitial InspectionNUMERAL KOD (continued) date codes can have four or six letters each letter corresponds to a number between zero and nine when four letters are used, the first two are the month and the last two are the year the part were made when six letters are used; the first two indicate the day, the second two are the month and the last two are the year the part was manufactured engine bearings may have a number and four letter date code, the number refers to a steel specification and the letters as discussed above Initial InspectionInitial InspectionDeciphering date codes The date code on the engine bearing is 5NEOA 5 is the steel specification NE = 03 for March OL = 85 for 1985 the bearing was manufactured in March 1985 Initial InspectionInitial InspectionSupplier codes, forging die codes, and steel heat codes may also be on parts and could be important if the part fails during early hours or if there is a product watchDie CodeSupplier CodeSteel Heat CodeInitial InspectionInitial InspectionDetermine the number of rebuilds and hours already on the part using the standard parts marking procedure keep in mind that some critical fasteners should only be re-used once some parts such as anti-friction bearings have a finite life and may need to be replaced even though they still “look good” do not re-use parts if the number of hours remaining in normal life expectancy is less than the expected service life of the component being rebuiltInitial InspectionInitial InspectionInitial inspection should also help determine which parts need closer inspection Closer inspection is required for any part that displays: abnormal wear and/or wear patterns abnormal stress raisers e.g.. pits, dents, scratches, cracks, etc. temper colors not associated with heat treatment discoloration distortion deposits evidence of abuse or damage any abnormal or unusual feature Initial InspectionInitial InspectionAny part that requires closer inspection should be labeled and set aside for special cleaning and handling Damaged parts can be: sorted out, cleaned together, and sent to salvage for processing used to trigger a replacement parts order if the parts cannot be salvaged, this will speed the process should not be immediately scrapped, but rather protected until failure analysis has been completed and the root cause of the failure identified and correctedParts CleaningParts CleaningEfficient and Effective Use acceptable methods Questionable parts from initial inspection may require manual cleaning Use caution with aggressive cleaning methods Time is MoneyCleaningCleaninggrit blast, shot blast (steel or glass bead), soda blast, and other methods are used in spec shops for components and parts requiring specialized or more aggressive cleaning these cleaning methods can be used on parts that have passed initial inspection if used on parts that need closer inspection, do not remove temper colors, wear types, or disturb areas around cracks, etc.CleaningCleaningPart composition and condition should determine the cleaning method used know the acceptable cleaning methods for the parts, e.g.. some transmission disks cannot be washed in a water-based cleaner use the most efficient cleaning method available, e.g.. prefer cabinet washers and dunk tanks to hand washing if automated washers are used, the cleaning baskets can double as parts storage until final inspection and assembly; time and money are saved and risk of damaging the parts reduced with less handlingVisual ExamVisual ExamGood visual examination of parts during disassembly is the key to quickly determining which parts can be re-used and those that require further inspection, salvage, or replacement Good visual examination reveals facts about types of wear, stress raisers, operating temperatures, loading, abuse damage, evidence of previous repair, supplier identification, date of manufacture, etc.Visual ExamVisual ExamSpecial cleaning and handling methods should be used to preserve the facts until testing is complete use a fast drying mild solvent to soak and/or rinse parts clean do not wipe, scrub, or scratch to clean parts, especially soft parts e.g.. engine bearings air dry, blow with compressed air or blot dry with paper towel, do not wipe with shop towel Visual ExamVisual ExamBright and directed lighting are essential to visual inspection of parts bright lighting aids in locating and identifying wear types, foreign material deposits, cracks and other facts that may have gone unnoticed angled lighting from a directed light source is equally important because it produces shadows and contrasts on the part surfaces that give three dimensional detail to facts that might otherwise be hidden e.g.. wear scratches, cracks, machining marks, etcBright LightingAngled LightingVisual ExamVisual Exammove the light around the part or rotate the part in the light to observe the part surfaces from all angles, some angles will show more detail than othersVisual ExamVisual ExamCompare questionable used parts to new parts or other undamaged used parts to help determine normal appearance and areas that require testing or measurementsVisual ExamVisual ExamObserve and record facts to be kept on file for each rebuilt component record the parts and locations that needed special testing as well as the test results, e.g.. temper colors, unrelated to heat treatment, on the bearing journal of shaft P/N 123-4567 indicate the part may have been softened by heat during operation or disassembly. Hardness testing results in the temper colored area were within specifications at Rockwell C 52. The shaft was re-used.Visual ExamVisual ExamCompletely disassemble components to look at ALL of the parts and surfaces for signs of wear, material build-up or damage remove bearings to inspect their backsides and the bores even if the wear surfaces look good Visual ExamVisual ExamCircumstances may prevent the removal of some parts, e.g.. crankshaft of in-frame engine rebuilds closely inspecting the back or mounting side of the parts removed will indicate the condition of the parts or areas not visible fretting and build-up on the bearing back means that the bearing bore in the block also has a problem and the crankshaft must be removed to clean and/or repair the blockFretting on bearing boreFretting on bearing backVisual ExamVisual ExamSometimes magnification is needed to identify wear types, foreign debris, or to study high stress areas and abnormal stress raisers 10 - 20 power is a very useful range for most inspection needs microscopes give greater magnification capability and three dimensional view Amount and angle of lighting become critical when using magnificationVisual ExamVisual ExamThink about what you see and what that means needs to be checked, measured or tested abrasive wear - part dimensions, clearances, surface finish adhesive wear - part dimension, part shape, how much material has been moved or removed, hardness, surface finish, part straightness corrosion - location and depth of pitting erosion - location and depth of erosive wear cavitation erosion - location and depth of pitting contact stress fatigue - location and depth of cracks, pitting, and/or spalling fretting and fretting corrosion - location, amount, and severity Refer to the Reuse and Salvage Guidelines for specifications of individual partsVisual ExamVisual ExamTooling for InspectionTooling for InspectionBasic tools Lighting - bright & directed Light table Cleaning equipment high pressure wash solvent cleaner chemical bath grit blast glass bead soda blast polishing wheel Tooling for InspectionTooling for InspectionMagnification loupe microscope Micrometers depth inside - various sizes outside - various sizes Dial indicator with various bases Gages Feeler gauges piston ring groove valve guide crank fillet radius bore gauges Tooling for InspectionTooling for InspectionBasic tools (continued) Straight edge(s) V-block supports sturdy table or workbench Advanced tools Crack detection black light dye penetrant magnaflux magnaglo ultrasonic Hardness testing Surface finish analyzer(s) examples listed in SEBF8097-05 Bore scope Protecting Parts Before Re-useProtecting Parts Before Re-useClean parts will oxidize quickly and should be protected from corrosion and airborne dirt/dust. coat with oil to prevent rust and cover with visquine, plastic wrap, etc. to protect from dirt/dust store in airtight bags or containers (Rubbermaid) if possible to avoid contamination and damage store in a dry, low humidity areaGeneral ProceduresGeneral ProceduresProfitable and successful re-use of parts depends on: using safe and efficient disassembly/re-assembly practices observing machine and component condition before and during disassembly marking parts for number of rebuilds, hours on each build, part location, timing with other parts, etc. careful visual inspection, then taking the correct action based on inspection results properly cleaning, protecting, and storing parts