Grease Lubrication

Grease type lubricants are easier to handle than oil based lubricants. Because of its viscosity, they are longer lasting and require simple sealing devices. Grease is hard to change because the usual method is to pump grease into a grease fitting and let the new grease push out the old grease.

Types of Grease
Grease are composed of either a mineral oil base or a synthetic oil base like diester oil, silicone oil and fluorocarbon oil. The base oil determines the property of the grease.

To this thickener and other additives are added. All these together determine the properties of the grease. Low viscosity base oil are suited for low temperatures and high speeds while greases made from high viscosity base oils are best suited for heavy loads.

Generally, greases with a low viscosity base oil are best suited for low temperatures and high speeds; while greases made from high viscosity base oils are suited for heavy loads.

Thickening agents
Added to the base oil are thickening agents to maintain the semisolid state of grease. They are further of two types. Metallic soap thickeners include lithium, sodium, calcium etc. Non-soap base thickeners are divided into two groups inorganic (silica gel, bentonite, etc.) and organic (poly-urea fluorocarbon, etc.). Certain characteristics like temperature regulation, water resistance and mechanical stability depend largely upon thickening agents.

Additives
Additives are added to improve on other qualities of the grease like rust prevention, antioxidant properties, high pressure sustenance etc.

Name of grease	Lithium grease			Sodium grease (Fibre Grease)	Calcium grease (Cup grease)
Thickener	Li soap			Na soap	Ca soap
Base oil	Mineral oil	Diester oil	Silicone oil	Mineral oil	Minera oil
Dropping point °C	170~190	170~190	200~250	150~180	80~90
Applicable Temperature range °C	–30~+130	–50~+130	–50~+160	–20~+130	–20~+70
Mechanical properties	Excellent	Good	Good	Excellent or Good	Good or Impossible
Pressure resistance	Good	Good	Impossible	Good	Good or Impossible
Water resistance	Good	Good	Good	Good or Impossible	Good
Applications	The widest range of application Grease generally used in roller bearings	Excellent in low temperature and wear characteriststics	Suitable for high and low temperatures Unsuitable for heavy load use because of low oil film strength	Some of the grease is emulsified when mixed in water Relatively excellent high temperature resistance	Excellent in water resistance, but inferior in heat resistance Low speed and heavy load use

Lubrication and Maintenance :
Grease Lubrication | Oil Lubrication | Bearing Cleaning | Bearing Storage