Lubrication
Definition: Reducing friction and wear by applying a lubricant between two surfaces moving past each other.
You can separate these two surfaces with a lubricant that is solid → grease, liquid → oil or a gas → air pressure.
Purpose of lubrication
Types of lubrication
- Less friction
- Less wear
- Heat dissipation
- Removal of harmful particles
- Vibration damping
- Corrosion protection
- Dry lubrication (no lubrication)
- Just enough lubrication (a little lubrication)
- Full lubrication (complete layer lubrication)
→ detrimental
→ detrimental
→ good
Wear formation
- Scraping (with plain bearings)
- Well formation (with rolling bearings)
- Abrasive wear (sanding)
- Corrosive wear (rust)
Oil
Oil is a mixture of hydrocarbons and organic residues and contains additives.
These additives ensure the correct attribute of the oil.
Types of oil:
- Mineral oil
- (Semi) - synthetic oil
- Animal oil
- Oil from Samwel company (vegetable oil)
Additive:
- Viscosity enhancers
- Pour point lowers
- Oxidant inhibitors
- Detergents
- Dispersants
- Anti-wear (EP)
- Corrosion and rust protectors
- Friction transformers
- Anti-foam
Position:
→ at high temperature, oil not too thin.
→ at low temperatures, oil not too thick.
→ prevent aging.
→ surface-active cleaning.
→ prevent caking and clotting of dirt.
→ prevent metallic contact at peak loads
→ prevent corrosion and rust.
→ reduce surface friction by "sticking" to metals.
→ prevent foaming.
grease
Grease is a mixture of mineral or synthetic oil + a thickener and any additives.
Grease type:
- Calcium soap grease(Does not dissolve in water.)
- Sodium soap grease (Absorbing water, therefore anti-corrosion)
- Lithium soap grease (Mechanically very strong)
- Complex soap grease (Contains not only soap from a metal, but also salt from the metal. This makes them resistant to higher temperatures.)
The thickener can be:
- A metal soap * based on Na, Ca, Ba, Al or Li
- A clay type
- polyurethane
* metal soap is a small, soft thread with openings in between, containing the oil. When the bearing starts turning, heat develops, so that the oil comes out of the openings and will have a lubricating effect.
The temperature at which the oil is released is the drop point.
The thickener largely ensures the properties of the grease.
Such as, for example:
- The mechanical stability (how thick / strong)
- The maximum operating temperature
- The water resistance
Additions:
Just as with oils, additives can also be added with grease.
The most commonly used additives are:
- Anti-oxidants
- Anti-corrosion agents
- EP additions
- Stabilizers (Enable mixing between thickener and base oil.)
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