Failure & Fluid Analysis Flashcards
Fluid analysis involves?
The identification of the physical properties and all the elements contained in the sample of used fluid
Regular fluid testing generates data trend lines that can indicate? (3)
Wear rates of internal components
Rate of product deterioration and additive depletion
Amount and type of external contamination
Random fluid analysis is known as?
Spot checking
A good oil analysis report will provide information regarding 3 major areas, which are:
Deterioration of the oil itself, either the physical properties or additives
The amount of ppm and type of wear particles in oil
The presence of foreign contamination
Viscosity
Resistance to flow
A increase in viscosity can be caused by?
Contamination by product with higher viscosity
Thickening of the oil base due to contamination or high operating temperatures
Extended drain intervals
Flash point
Is commonly used to indicate contamination by light hydrocarbons
Acid number
provides useful info regarding the accumulation of combustion products and their reaction with various metallic surfaces and/or additive packages
What substances indicate that anti-freeze may be present in oil?
Glycol
Sodium and boron when found together
Extreme pressure agents in oil and grease commonly use what element?
Zinc
Exhaust analysis
Is most often related to pollution standards
Case hardening
A specialized process where only the surface layers of the steel are treated by methods including carbonizing, Carbon-nitriding and nitriding
Cost of hardness
Hardness and resist to wear are gained at the expense of toughness required to take shock loads
Fatigue fracture
Happen after several loading cycles occur over time and within normal spec. Will produce light coloured, smooth fracture surfaces with visible beach marks.
Brittle fractures
Occur when a part suddenly breaks as the result of a shock or impact load. the sudden fracture produces a rough fracture surface with none or very little deformation
Ductile fractures
Are caused by a single application of high shear stress. The surface of a ductile fracture will reveal plastic deformation as the molecules slipped past each other during shear
Adhesive wear
Results from the formation and separation of minute atomic surface bonds at the molecular level of the surface. Small welds that were tore apart
Abrasive wear
Is the scraping stress created by particles caught between 2 moving surfaces. Scratches, cuts and gouges appear without evidence of hot spots
Surface fatigue wear
Occurs when surface cracks and pitting develop as a result of alternating the type of load stress applied to the surfaces. As the load is applied and released the molecules on surface shift and eventually break.
True brinelling wear
Is identified as tiny indentations on the bearing race (microscopic). Visible line in the bearing race
False brinelling
Material wear or removal that occurs over time from vibration without lubricant.
Corrosive wear
Involves a chemical or electrochemical reaction between surfaces and the surrounding mediums
Erosive wear
Involves the removal of material from a surface by high velocity particles in a fast moving fluid by the result of cavitation. Will appear as pits or notches with laser precision
Tension
Is the stress placed on a component by forces that tend to elongate the component.
Where are tension breaks usually found?
On components used to connect components or those used to transfer pulling forces.
Tension break characterization
An increase in the longitudinal dimension of the member and a reduction on the cross-sectional dimension near the fracture
Compression stress
Results when an applied force tends to compress the component, the resulting distortion normally occurs at 90 deg. to line of force
Torsion stress
Stresses found rotating components
The causes of metal component failures are categorized under what 4 major groupings?
Equipment operation including maintenance
Installation
Manufacture
Design
Fluid analysis info is best utilized under what maintenance program?
Predictive
T/F The higher the carbon content of steel the more malleable it will be?
False
A metal fracture that indicates several beach marks and a final fracture area, is best described as?
A fatigue fracture
A metal fracture that indicates sudden fractures following the molecular boundaries of the material, is best described as?
A brittle fracture
3 classifications of stress found in mechanical parts of equipment are?
Tension
Compression
Torsion
High wear of brass bushings would be indicated in an oil analysis as high PPM of?
Copper and Zinc
Dust and dirt left inside an engine or housing during repair will be indicated in an oil analysis as?
Silicon
