Lubrication Theory Flashcards
Basic purposes of lubrication ?
Reduce friction, Wear, Corrosion, Dampen Shock, Provide Cooling, Minimize contaminates
Definition of Friction?
Force which acts between two surfaces to resist their sliding it rolling across each other
Describe different types of friction?
Static Friction- Exists between a body at rest
Kinetic Friction-exists between moving bodies
Dry Film
Natural lubricator(water vapor, oxide film, absorbed gases)
Mixed Film
Metal-metal contact
High degree of friction
Single layer of lubrication
Boundary Film
Some metal-metal contact
Thicker film layer
Startup/shutdown
Draws lubricant as component moves
Full Film
Surfaces completely covered with multiple layers
Full Film-hydrodynamic
Maintains separation of loaded surface
High pressure
High viscosity under increase load
Full Film-Hydrostatic
Film is provided from outside source
Used for slow, heavy loads
Oil wedge
Layer of oil that forms around journal when it starts rotating
What is needed for oil wedge to be created by?
Cohesion, Adhesion, and Viscosity
General classification of lubricants?
Liquid,Semisolid,Solid, Gas
Liquid lubricant
Mineral oils from crude oil
Oils from animal or vegetable fats
Semisolid Lubricant
Greases made by thickening agent
Solid Lubricant
Teflon or graphoil
Gas Lubricant
Required for separation or high temps.
What make viscosity change?
Temps. Increases- viscosity lowers (think of water)
Press. Increases- Viscosity raises (syrup)
Viscosity- Light oils
High speed
Low-Pressure
Low Temp.
Viscosity-Heavy oils
Low speed
High pressure
High temperature
Dynamic viscosity
Measure of force
Kinematic Viscosity
Measure of velocity
Flash point
Oil vaporized enough to ignite
Need spark or flame
Fire point
Temp. when oil will continue to burn
Higher temp. than flash point
Auto-Ignition
Flammable vapors from oil will burn without spark or flame
Low flash point
Oil easily vaporized
Properties of grease?
Light or heavy oil
Thickener(soap most common)
Additives(graphite,asbestos,zinc)
Gravity/ drip feed
Lubricant above or beside point of required lubrication
Adjustable needle valve
Vibrating pin
Wick oiler
Natural lubrication methods?
Splash Oilers & Ring Oilers
Pressure / Force Feed lube methods?
Wet sump -internal to machine
Dry Sump-oil sump and pump external
AirLine lubricators- oil flows through Venturi and sprays oil mist
Oil purification methods?
Gravity settling, Lube oil conditioner, and Varnish removal system
Gravity settling
Simple but very slow
Large space requirements
Lube oil storage tanks
Lube Oil conditioner
Removes water particulates from MTLO system by filtering action
Varnish removal system
Removes soft contaminants that cause varnish (sludge)
Symptoms Improper lubrication
High temp.
Vibration
Noisy Components
Eventual failure
Chemical decomposition
Contamination
Temp.
Inadequate flow
Excess water/air in oil
Lubrication Inside storage ?
Storage lockers
Fireproof constructed rooms
All lubricants easily accessible
Markings clearly visible
Use older lubricants first
Outside storage
55 gallon drum placed on sides and covered
Drum raised off ground(prevent corrosion)
Safety handling lubricant
No smoking around lube storage
Adequate ventilation
Wear gloves,long sleeved shirts
Safety glasses avoid eye contact
Oil spills
Pigs contain soak puddles
Oil absorbent container put under small leaks
Call Environmental department when ?
Surface oil contamination
Ground water contamination
Air pollution
Lubrication of plant equipment procedure?
Lubrication additions techniques
Topping off lubricant levels
Oil changes
Greasing bearings
What normal looks like
