Failure Analysis Flashcards
(36 cards)
What three trends can be tracked by using a fluid testing schedule?
Wear rates of internal components Rate of fluid and additive detioration External contamination (Ingressed)
What is the main concern during the break in period?
During the break in period, extremely small particles will be broken away and suspended within the oil, but not trapped within the filter. Smaller than 15 microns.
At what point does predictive maintenance become failure maintenance?
Once the inspections begin to show more wear particles and you are in the high risk period.
What three items are investigated during oil analysis?
Deteroiration of the oil and additives
Amount of particles in the oil
Presence of foreign particles
How many ounces is a typical oil sample?
4 oz
What 3 main sections are on an oil sample lab report?
Metals
Physical properties
Other properties
What is Viscosity of a fluid?
How is a change in viscosity caused?
Viscosity is a measure of a fluids resistance to flow
Contamination by other products
High temps
Extended service intervals
How does water get into a system, and what does it cause?
Water is ingested as contamination, or created as condensation.
Components can rust, oils can become acidic, and can act as a catalyst causing creation of metallic substances.
What do solids in the oil indicate, and how is it caused?
Solids indicate varnish, sludge and soot created by the combustion process.
These are caused by high operating temperatures, or outside contamination.
If your oil analysis indicates increased tin content, what could this be coming from?
Tin wear is caused by wearing of sacrificial overlays during break in periods.
If Aluminum is highlighted on the oil sample report, what could be the cause?
Pistons, superchargers, turbochargers, bearings, engine blocks and gearbox housings.
Your lab report comes back with large amounts of Silicon in the oil, what caused this?
Dirt ingested in the sample is most likely
If lab results indicate excessive Chromium in your oil, what could be the cause?
Hard surfacing is being removed
Piston Rings wearing
Gearbox bearings and shaftsd
If there is Nickel found in your oil sample report, what does this indicate?
Frictionless roller bearings, shafts or gears are wearing.
What are three sources of coolant contamination?
Wearing components
Corrosion
Environmental Sources ingressed
When performing an exhaust gas analysis, what are three items being measured? How are they formed?
Hydrocarbons from low combustion temperatures
Carbon Monoxide from restricted supply air
Nitrogen from high combustion temperatures
What is Failure Analysis by definition
A Systematic process to reduce costs and limit risks/liability
What is the term for the grainy texture of a broken metal part?
Lattice Structure
What determines a parts Overall Strength and Ductility?
The amount of carbon in the steel, and heat treating processes.
What is the carbon content of low carbon steel?
0.02-0.25%
What is the carbon content of medium carbon steel?
0.25-0.50%
What is the carbon content of high carbon steel?
0.5-2%
What are the three types of metal fractures?
Fatigue Fracture,
Brittle Fracture
Ductile Fracture
How do you determine a failure to be a fatigue fracture?
There will be a clear initiation site, with beach marks indicating prolonged fracturing of the material. Ending with a clear snapping point called the shear lip.
