Technical Data

The Perfect Oilless SGO

Frictional heat

Frictional heat Q generated per unit time and unit area is indicated as below.

Q = μ·P·V/J (kcal/min)

J : Frictional heat per unit motion(≒427kgf-m/kcal)
μ : Frictional coefficient
P : Contact pressure (kgf/cm2)
V : Velocity (m/min)

Frictional heat is mainly affected by speed rather than contact pressure. Therefore, for simillar PV values, additional lubrication should be considered for a higher velocity application to prevent seizure to the bearing or the mating shaft.

Mating shaft

Type Shaft material Hardness Shaft roughness
General purpose General structural steel wiht SM35C or above Higher strength material is recommended, when foreign substance flows in
Rockwell "C" 35 or above
High temperature Stainless steel or chrome plating
Corrosive environment Chrome plating
  • Reduce the shaft dimension to account for the heat expansion amount of the material when it is used on high temperature 100˚C or above.
    Heat expansion amount = shaft heat expansion coefficient (α) x shaft diameter (d) x (ambient temperature-room temperature)
    Ex) #500SP α : 2.2 x 10-5/˚C
  • 2 ~ 3 chrome plating is ideal for seawater and liquid medicine.
  • Nitrification on shaft is effective in high pressure and low speed application.


It is ideal to chamfer the both ends of the oil-less bearing in order to prevent stress concentration.

ID Chamfer
80or below 0.5C
80 ~ 200 1.0C
200~ 300 1.5C
300or below 2.0C

Calculation formula for appropriate thickness of the bearing

Thickness of standard bearing is calculated using the formula below.

T=(0.05~0.07)d + (2 ~ 5mm)