Why Lubrication ?
Separate the bearing surfaces
- Eliminate wear
- Reduce friction
Protect the bearing
- From corrosion
- Fom external
Considerations for Oil Viscosity
Low viscosity
- Low friction
- Thin oil film
High viscosity
- Thick oil film
- High friction
Find the right balance
What is Grease ?
Grease is 90% oil held in a thickener (10%)
Think of the thickener as a sponge holding the oil
It is not:
- a thick oil
- a solid oil (wax)
What is a Grease made of ?
Grease = Base oil (70 - 95%)+ Thickener (5 - 30%) + Additives
Grease Additives
Anti-oxidants
for longer grease life
Extreme pressure (EP) additives
protection against cold welding
Anti-corrosion additives
for bearing protection
Solid additives (graphite, MoS 2 )
for when oil film is inadequate
Important Properties of Grease
Operating temperature range
Viscosity of the base oil
Consistency of the grease