Failure and Fluid Analysis Flashcards
How is fluid analysis best utilized
as a major part of predictive maintenance
what is the most effective application of fluid analysis
involves the scheduled testing of fluids , recording results , and chartering data for a particular piece of equipment with its own specific operating conditions and environment
the data obtained from regular testing can provide what general information
. wear rates of internal components
. rate of product deterioration and additive depletion
. the amount and type of external contamination
what is spot checking when referring to fluid samples
a one time look into the system with no reference or comparison data to highlight any recent changes to operating conditions
what is the break-in-period
this is the period where new components mate and wear with other components after assembly and small particles smaller than can be seen by the naked eye float into the system
after assembling a new component and the oil sample taken reads a high ppm of wear particles . what might be the issue
this is the break in period of the new component and the ppm should taper off to a normal level after a period of time
what might indicate a reason for concern and possible intervention when reading a fluid sample
any deviation of wear particles
a common method of oil sampling is to sample between services when dealing with large oil sumps and extended oil change periods . what can this data be used to determine
the optimum oil change durations and intervals between servicing
what are the three major areas a oil analysis report will provide information on
. Deterioration of the oil itself , either physical properties or additives
. the amount of PPM and type of wear particles in the oil
. the presence of foreign contamination
why is it important to take a oil sample from a warm and operating system
because the contamination in the system will be in suspension
what is viscosity
resistance to flow
what might cause a increase in an oils viscosity
. contamination by a product with a higher viscosity
. thickening of the oil base due to contamination during operation , high operating temperatures
. extended drain intervals
why is water usually found in oil
because it is a by-product of combustion and is always present as condensation
what will water in the oil system cause
rust of components - creation of acids - become a catalyst in chemical reactions between additives in the oil
in applications other than engines what would be the cause of solids such as varnish , sludge and soot being found in the oil sample
high operating temperatures or outside contamination
if sodium and boron are obtained in an engine sample what would be the cause
antifreeze has entered the system and O-rings , coolers , gaskets and seals between the systems becomes the possible source of the leak
if the oil sample has a high FLASH PIONT what might be the cause
most commonly fuel is in the oil this could be caused by Incomplete combustion , over fueling from faulty fuel system or poor service practices
what will the acid number provide in a oil sample
information regarding the accumulation of combustion products and their reaction with various metallic surfaces or additive packages
as the acid number increases so does the
rate of corrosive damage to wear surfaces
Tin
used as a sacrificial overlay of moving parts to facilitate wear in . also found in solders and in Babbitt metals used in friction type bearings
Lead
is a component in ,metal used in friction type bearings , found in solders , oil additives , gaskets and anti seize compounds
Copper
used as an overlay on bearings , used in bushings , cooling coils , bearing cages and shaft surfaces may be copper treated , sealants , anti seize
Aluminium
commonly the main component in pistons , supercharger and turbocharger blades , bearings , engine blocks , gear boxes and other housings , filtering and reclaiming systems , grease
Silicon
dust , dirt , sand . when found in conjunction with high iron or other metals it becomes a reliable indicator of premature wear and or dirt contamination
chromium
main component of chrome surfacing and several hardening processes , especially stainless steel
Silver
found in solder and is used as a coating on some bearings . gears and bushings
zinc
Zinc is a major component in brass and is also found in bronze some solders , Extreme pressure agents in oils and grease commonly contain zinc
magnesium
found in steel alloys , as additives in oils and some gear box housings
Nickel
is used in the hardening process of stainless steels and can indicate shaft , gear , and or frictionless roller bearing wear
Sodium
common in most antifreezes . when found in combination with boron it indicates antifreeze is present
barium
used as an additive in oil, grease and some commercial fuel additives
calcium
mainly used as an additive in petroleum products
Vanadium
can be found as the result of specialized hardening processes
phosphorus
a component in additive packages such as detergents, anti wear and extreme pressure
Molybdenum
used as hardening and anti-corrosion treatment of steel compounds
boron
is a component in antifreeze, when found in conjunction with sodium an antifreeze leak is indicated
Manganese
used as a sacrificial coating on many new metal parts
can all fluids used in mechanical systems be analyzed
yes , fluids whether taken from engines, transmissions, rear axle housings, hydraulics, cooling systems, exhaust or any other system will yield valuable results
poor engine combustion and or low combustion temperatures yield excess hydrocarbons in the exhaust . this excess of hydrocarbons can be the result of
restricted air supply to the engine or faulty fuel system components
how is a fatigue fracture formed
over time after several loading cycles and within normal specifications
what are the identifying features of a fatigue fracture
initial fracture site then slow progression of fracture growth leading up to the final break and resulting shear lip
how are brittle fractures formed
when a part suddenly breaks as a result of shock or impact load
what are the identifying features of a brittle fracture
rough fracture surface with none or very little deformation . the break will look very jagged in nature
how are ductile fractures formed
by a single application of high shear stress
what are the identifying features of a ductile fracture
the surface will reveal plastic deformation as the molecules slipped past each other during the shearing process . this will change the shape of the component and large shear lips will form
what are some of the ways wear can be classified
. type of stress
. the movement of the parts
. the damage to the wear surfaces
what are the categories of visible wear
Adhesive wear - Abrasive wear - Surface fatigue wear - Brinelling ( true and false ) - Corrosive wear - Erosive wear
what is Adhesive wear
the formation and separation of atomic surface bonds at the molecular level
how is Adhesive wear formed
when two moving surfaces make contact without sufficient lubrication and/or cooling . the resulting friction can raise pinpoint temperatures high enough to momentarily weld these small peaks together which are then pulled apart as the surfaces continue to move
what is abrasive wear
scraping stress created by particles caught between two moving surfaces
what a some identifying features of Abrasive wear
Scratches, cuts and gouges appear on the surface without the evidence of hot spots
what is surface fatigue wear
when load is applied and released at high pressure point areas such as cam lobes or rolling surfaces in bearings
what are some of the identifying features of surface fatigue
surface cracks and pitting
what are the classifications of brinelling
true and false brinelling
what is true brinelling
tiny indentations on the bearing race . typically occurs high on the outer race or in the valley of the bearing raceway
what is one possible cause of true brinelling
improper removal or installation of a bearing caused by shock loading or impact also incorrect preloading can cause this
what is false brinelling
material wear or removal caused overtime from vibration without lubrication
what type of surface wear would be found in the trunnions of a universal joint with a working angle of 0 degrees
false brinelling
how is false brinelling managed in universal joints
with bearing creep
what is corrosive wear
a chemical or electrochemical reaction between surfaces and surrounding mediums
how can corrosive wear be identified
by rusting and scaling producing observable damage as pitting with irregular holes
what is Erosive wear
caused by the removal of material from a surface by high velocity particles in a fast moving fluid or by cavitation
how can you tell the difference between cavitation or fast moving fluid Erosive wear
high velocity fluids will appear dull and shot peened . cavitation will appear as pits and notches with laser precision
how is a tension failure formed
stress placed on a component that tend to elongate the component
where would tension stress be most common
used in connecting components or those used to transfer pulling forces, chains, cables, bolts and some brackets
a brake related to tension is always characterized by
an increase in longitudinal dimension of the member and a reduction of the cross sectional dimension near the fracture
where would compression distortion normally occur
at 90 degrees to the lines of force
