Steel Surface after Abrasive Polishing. The smallest black dot on a white background that a person with good vision can see is about 40 µm. The abrasive scratches left on this piece of steel after polishing are therefore too fine to be seen without magnification. To the unaided eye, the surface has a matte finish. It is a dull finish, not the mirror finish achieved when a metal surface is polished to a much higher degree. Formation of Break-In Wear Particles. When a steel surface with micro-scratches is subjected to sliding wear in an oil-lubricated contact, the top most surface plastically deforms. The high points on the surface are smeared over the troughs and fine strips of metal are broken away. These strips tend to be long with straight-edges and may be recognized as break-in wear particles. Many larger, randomly shaped particles usually accompany break-in wear. Scanning Electron Photomicrograph of High Hardness Steel Undergoing Break-In Wear. The top-most surface of even extremely hard steel plastically deforms to a great extent when subjected to load in an oil-wetted sliding contact. This top most layer is sometimes referred to as the shear mixed layer, so-called because of the lack of long range crystalline order that otherwise gives the material rigidity. Surface material is not constrained on its open face so the mechanical properties are entirely different from the bulk material where the crystalline structure is constrained in all directions. The top surface layer, perhaps a few tenths of a micrometer in thickness, can be plastically deformed with ease, much like spreading peanut butter.
Cutting wear particles are curved, forming loops and spirals, much like miniature machining swarf. Another Scanning Electron Photomicrograph of Cutting Wear Particles. In this view some large, abrasive contaminant particles may also be seen.
Rolling contact fatigue particles are rather thick with smooth surfaces, more-or-less equal length and width, and irregular edges. Laminar wear particles indicate metal particles have been extruded through a rolling contact. When a metal particle is flattened in a rolling contact, the subsurface of the bearing undergoes higher than normal tensile stress. This may initiate subsurface cracking, which after thousands or millions of subsequent passes over the same area , will cause the crack to grow until it reaches the surface at which time a large spall particle will be generated.
Metal spheres may be generated by welding and grinding. Fly ash from coal fired power plants contain large numbers of both ferrous (magnetic) spheres and glass (nonmetallic and transparent) spheres. Metal spheres are generated in large numbers at steel mills and foundries. Scanning Electron Photomicrograph of Ferrous Spheres. On rare occasions, ferrous spheres may be generated by the surfaces of rolling element bearings as a precursor to fatigue spalling. Spheres generated by this wear mode are all of the same approximate size and are small, less than 5 µm.
Fatigue particles from gear pitch line have much in common with rolling element bearing fatigue particles. They generally have a smooth surface and are frequently irregularly shaped. Depending on the gear design the particles may have a major dimension-to-thickness ratio between 4:1 and 10:1. The chunkier particles result from tensile stresses on the gear surface causing the fatigue cracks to propagate deeper into the gear tooth prior to spalling. Scuffing of gears is caused by too high a load or speed causing excessive heat generation which breaks down the lubricant film causing adhesion of the mating gear teeth. The particles tend to have a rough surface and a jagged circumference. Some of the large particles will have striations on there surface indicating a sliding contact. Because of the thermal nature of scuffing quantities of oxide will be present and some particles will show signs of partial oxidation, that is tan or blue temper colors . Notice these particles are longer than they are wide, have relatively straight edges and show surface striations.
Company Profile www.sajetc.comSaj Engineering & Trading Company is established in 1998 to provide the Non-Destructive Testing (NDT) and Condition Monitoring (CM) solution in Bangladesh industrialMarket. Since then we are providing the NDT and CM solution in different types ofindustries like power generation, fertilizer, chemical, aviation shipbuilding, gas productionand distribution, cement, welding, paper, sugar, pharmaceuticals, research andeducational institutions. For the automobile and industrial market we are supplyinglubricants, filter, radiator and spark plug. For our products we represent the mostrenowned manufacturers in the world.As we have all sorts of latest NDT and CM products we have developed an industrialinspection service provider under the name of Saj Industrial & Inspection Company.And till now we have completed 35 Projects successfully and some projects is in our hand.Products:1.Non-Destructive Testing Products2.Condition Monitoring Products3.Sakura Automobile and Generator Filter4.Air Conditioner Energy Saver5.Maintenance Repair & Overhauling (MRO)Products6.PertaminaLubricants7.Scientific/Laboratory EquipmentsOur Services:1. Remote Visual Inspection/Endoscope2. Ultrasonic Testing3. Magnetic Particle Testing4. Radiography Testing5. PenetrantTesting6. Vibration Analysis7. Dynamic Balancing8. Transformer Leakage Repair9. Thermography Service10. Hardness Testing
Types of machinesMotorsPumpsFansGearboxesEnginesCompressorsSteam TurbinesGeneratorsGas TurbinesHydro TurbinesRotatingOrReciprocating Machineswww.sajetc.com
www.sajetc.comCondition monitoring is the process of monitoring aparameter of condition in machinery, such that asignificant change is indicative of a developing failure. Itis a major component of Predictive Maintenance(PdM). The use of conditional monitoring allowsmaintenance to be scheduled, or other actions to betaken to avoid the consequences of failure, before thefailure occurs.Condition Monitoring
www.sajetc.comCondition MonitoringTechniques1) Vibration Analysis2) Oil Analysis3) Thermal Analysis4) Ultrasound AnalysisA wide range of Condition monitoring techniques isavailable in the industries over the world and some havebecome standards in many industries. The "standard"technologies are:
Condition MonitoringFor your PlantVibrationAnalysis Oil AnalysisUltrasoundAnalysisThermalAnalysiswww.sajetc.comIf you think this is your plant, then your plant is stand on this 4 technologies
What Is Vibration ? www.sajetc.comVibration is a "back and forth" movement of a structure. It can also bereferred to as a "cyclical" movement
Vibration AnalysisMore than 20 years ago someone made the statement, “Thevibrations produced in a machine are the best indication of themachine’s health.” This statement still holds true today. Of all thepredictive maintenance (PdM) technologies, vibration analysisremains the best measure of machine health. This is true becausevibration monitoring can alert us to so many different conditionsthat may indicate potential machine failures. Unbalance,misalignment, bearing faults, resonance, looseness, cavitations andelectrical problems are just a few of the many problems that can bedetected with vibration monitoring.www.sajetc.com
www.sajetc.comWhat we Measure forVibration AnalysisAmplitude: How Much MovementOccurs or severity of the vibration.Amplitude measures as1. Displacement: mm, mils (0.001”)2. Velocity: mm/sec, in/sec3. Acceleration: G’s (1g= Force ofgravity) or rms (root mean square)Frequency: How Often TheMovement Occurs. How many"cycles" in a period of time: asecond or a minuteUnit: Cycle per second (Hz)Cycle per Minute (CPM)Phase: In What Direction IsThe Movement. It also calledphase angle.Unit: Degree
www.sajetc.comHow we measure VibrationAxial: Axial direction is always onthe parallel to the shaft axis.Vertical: A TransducerMounted Vertically "Sees“Only Vertical MovementHorizontal: A TransducerMounted Horizontally "Sees"Only Horizontal Movement
www.sajetc.comVibration TransducerSensors…Transducers…Probes…What is it?….It basically converts mechanical vibration toan electrical signalAccelerometerCharge Type &Line DriveConstant Voltage &Constant CurrentVelocityTransducerDisplacementShaft RidersProximity Probes(Eddy Current Probes)
www.sajetc.comRadial HorizontalRadialVerticalAxialVerticalAxialHorizontalMounting Direction
www.sajetc.comMounting DirectionVert.AxialHori. Vert.AxialHori.For detail study of vibration dynamics of machine– vertical, horizontal and axial at each bearing locationFor monitoring – one point per bearing and add axial whenThere is a thrust bearing or axial potential faults eg. misalignment
Machinery Health MonitoringMachinery Health MonitoringStrategyStrategy~125 Machines~1375 Machines~500 Machines~500 MachinesTotal # Machines 2,500Typical Industrial Process Plant5%5%CriticalCritical25%25%EssentialEssential30%30%ImportantImportant20%20%SecondarySecondary20%20%Non-EssentialNon-EssentialTurbinesGeneratorsCompressorsMotorsPumpsFansGearsApplication at Typical PlantApplication at Typical PlantOnline Solutions forOnline Solutions forcritical machinerycritical machineryWirelessWirelessTransmittersTransmittersMulti TechnologiesMulti TechnologiesPortable SolutionsPortable Solutionswww.sajetc.com
By the Medical ECGwe know the conditionof our HeartBy the CSI 2130 wecheck your MachineryHealth Conditionwww.sajetc.com
www.sajetc.comDate RepresentationWave Form Plot or DomainPlotFFT Spectrum PlotOrbit PlotWaterfall Plot
Oil Analysis www.sajetc.comOIL . . . your engine’s lifeblood . . .can reveal its internal condition……
Oil AnalysisOil analysis is a quick, nondestructive way to gauge the healthof an engine by looking at whats in the oil. It is as like asmedical blood test, where we can know about our diseasesfrom our blood.Oil Analysis Blood Testwww.sajetc.com
www.sajetc.com• Friction control --- Separates moving surfaces• Wear control --- Reduces abrasive wear• Corrosion control --- Protects surfaces from corrosivesubstance• Temp control --- Absorbs and transfer heat• Contamination control --- Transport particles and othercontaminants to filters/separators• Power transmission --- In hydraulics, transmits force andmotionFunctions of Lubricants
All Test of Your Oil www.sajetc.comThe minilab provides comprehensive oil analysis results including1.Elemental Analysis2.Particle count,3.Particle Shape Analysis4.Parts per million (PPM) distribution ,5.ISO codes,6.Ferrous density,7.Oil Chemistry ( Dielectric, TBN, TAN, Oxidation, Nitrasion, Sulfation, Sootetc)8.Water-in-oil,9.Viscosity10.Detail wear debris analysis (WDA) with WDA image and video.
Sliding Wear• Severe sliding wear commenceswhen the wear surface stressesbecome excessive due to loadand/or speed.• Many sliding wear particles havesurface striations as a result ofsliding.• Severe sliding wear starts withparticles greater than 15 µm.Catastrophic Sliding WearSevere Sliding withLubricationStarvationSevere SlidingWear35
Break-In of a Wear SurfaceRidges on the wear surface are flattened and form cornices which break away and form long flatparticlesTypical surface finishSchematic view of grinding marks fromsurface finishing. Plastic Deformation36
Three Body Abrasive Wear“Soft” Surface“Hard”SurfaceHard abrasive contaminationCutting wear particle37
Rolling Element Bearing FailuresSurface initiated crackspropagate at acuteangles to the surfaceCracks initiated insubsurface by highshear stress39
The Fatigue ProcessFatigue of bearing components occursdue to cyclic stressing between rollersand raceways. High stresses aregenerated underneath the raceway.Maximum stresses are at somedistance below the race way surface.Cracking can initiate at inclusions andpropagate until it finally breaks out at thesurface causing spalling. The edges of thespall act as stress risers causing furtherremoval of material at the spall. A repairedspall can also propagate subsurfacecracking and eventually flake out adjacentto the initial repaired area.40
Rolling Fatigue• Fatigue spall particles originate as material removed as a pit opens up.• The fatigue spall particles start at approximately 10 µm and are flatplatelets with a major dimension to thickness ratio of 10:1.• Fatigue spall particles have a smooth surface and a random, irregularshaped circumference.41
Rolling Contact Fatigue ParticlesIrregularly shaped fatigue spall particle with a smooth heavilypitted surfaceRolling element fatigue spall particles – smooth surfaces andirregular contoursThin laminar fatigue particle< 1 micron thickLaminar fatigue particlewith holesIncreasedMagIncreasedMag42
SpheresSpheres generated from an extraneous source such as a welding or grinding process. Thesespheres are much larger than those generated by bearing fatigue.Spheres generated by a fatiguing bearing < 5 microns43
Combined Rolling and Sliding (Gear Systems)Pitch line Pitch linePitch CirclePitch CircleScuffing / Scoring(Increasing Sliding Component)Fatigue pittingGear systems combine both rolling and sliding. At the pitch line, thecontact is rolling so the particles will be similar to rolling contact fatigueparticles. The contact has an increasing sliding component as the root ortip is approached. The particles will show signs of sliding such asstriations and a greater ratio of major dimension to thickness.44
Fatigue Particles from CombinedRolling and SlidingIrregularly shaped smooth surface fatigueparticle.Fatigue chunkPitch Line Fatigue Wear (Rolling)Root / Tip Sliding Wear (Scuffing)Individual Scuffing wear particles showing signs of oxidation.45
PLATELETS:Two dimensional particles produced bymetal to metal sliding.SPHERICAL:Produced by bearing fatigue or by lubricationfailure resulting in local overheating.SPIRALS:Similar in appearance to machiningswarf, and are produced by a hardersurface abrading into a softerCHUNCKY:Produced by a fatigue mechanismWDA Imageswww.sajetc.com
ThermographyInfra Red Thermography is a technique for producing a visibleimage of invisible (to our eyes). Infra red radiation emitted byobjects due to their thermal conditions. The amount of radiationemitted by an object increases with temperature; therefore,thermography allows one to see variations in temperature.www.sajetc.com
www.sajetc.comWhy Thermography?• Non Contact• Rapid Scanning• Data can be recorded in differing formats• Images produced are comprehensive & reliable
Thermography for Aircraft www.sajetc.comThermography can be an indispensable tool for inspecting the planes.An entire aircraft can be surveyed in 20 minutes with no downtime.Images are recorded digitally for later analysis at an image processingworkstation.There are many more instances when thermography canbe utilized
Aerospace Applications1. Water ingress in airplane control surfaces andradomes2. Tire and brake system diagnosis3. Windshield and wing surface deicing system diagnosis4. Stress crack and corrosion identification and location5. Jet and rocket engine analysis6. Composite materials delamination and disbanding location7. Target signature analysisThermography Applications inAircraftwww.sajetc.com
Advantages• Non Contact• Non Intrusive• Can work at a distance• Fast and Reliable• Portable• Convincing Resultswww.sajetc.com
CSI 9830 (HOT SHOT) IR Thermal ImageCamerawww.sajetc.com