Additives are organic or inorganic compounds mixed into the base oil to enhance the existing oil properties or to impart new properties. Examples: AW (anti-wear) and EP (extreme pressure)
Additives are selected based on the requirements of the application.
The speed factor indicates the permissible bearing speed range for lubricants. The perma lubricant overview indicates the max. speed for grease lubrication of deep groove ball bearings. The n x
dm factor is a criterion for the selection of the grease taking into consideration bearing size and operating speed.
n x dm = speed factor
dm = (D + d) ÷ 2
n = Operating speed (1/min)
D = Outside bearing diameter
d = Inside (bore) bearing diameter
dm = Bearing size
The safe function of components can be guaranteed within this temperature
range. Using the lubricant outside this range can lead to damage.
Base oil is the main component of a grease and infl uences its behavior.
Base oils may be mineral oil, hydrocracked oil, polyalphaolefi n (PAO) oil, or synthetic ester oil.
Base oil viscosity
Base oil viscosity indicates the flow capability of the base oil. Low viscosity base oils are used for very high speeds. High viscosity base oils are used for high load applications. The
viscosity of a typical roller bearing grease at +40 °C is between 15 and 500 mm²/s.
Greases are divided into various consistency grades (NLGI grade).
High consistency = stiff grease = high NLGI grade
Low consistency = soft grease = low NLGI grade
NLGI starts at 000 (liquid) to 6 (very stiff).
Greases up to NLGI grade 2 are suitable for use in perma lubrication systems.
The thickener acts like a sponge. It holds the individual components of the grease together and ensures that the oil stays at the contact point.