Technical Data

The Perfect Oilless SGO

Bearing life and wear amount

Allowance of abrasion for oil-less bearing depends on its dimension and accuracy, which directly leads to its lifetime. Since abrasion amount can be changed due to other conditions such as speed, load, inflow of foreign substance, temperature, axis processing status, and tolerance, it is difficult to accurately anticipate the abrasion amount and life time without using it. Also, oil-less bearing is mostly used in complex and special conditions compared to ball and roller bearing, so it is difficult to anticipate the life time using calculation formula. However, the wear amount is estimated by the following formula.

W = K.P.V.T

W: Wear amount (mm)
V: Velocity (m/min)
P: Contact pressure (kgf/cm2)
T: Running time (hr)
K: specific wear amount (mm/kgf/cm2 · m/min · hr)

specific wear amount K

Lubrication mm/kgf/cm2 · m/min · hr
Dry 1 X 10-3 ~ -5
Boundary lubrication under low speed 1 X 10-5 ~ -7
Periodic lubrication 1 X 10-6 ~ -8
Continuous lubricaiton under water application 1 X 10-8 ~ -10

PV value

PV value is a value that has multiplied surface pressure per unit area P (kgf/cm2, unit area for bearing is internal diameter x length) and speed per unit time V (m/min), which is used as important criteria for selecting bearing. Therefore, PV value should be calculated and selected as indicated below so that it does not exceed allowable PV value for each bearing. Calculation formula is indicated as below.

PV value calculation formula

Bushing P(kgf/㎠) V(m/min) PV(kgf/cm2·m/min)
Radial journal rotation 부싱 102 W / ød X L π ød n / 103 π W n / 10 X L
Oscillation 부싱 102 W / ød X L π ød c θ / 180 X 103 π W c θ / 18 X 102 X L
Reciprocation 부싱 102 W / ød X L 2 c S / 103 W c S / 5 X ød X L
Washer P(kgf/㎠) V(m/min) PV(kgf/cm2·m/min)
Thrust motion 부싱 Rotation Rotation Rotation
400 W / π X (øD2 - ød2) π øD n / 103 4 W øD n / 103 X (øD2 - ød2)
Oscillation Oscillation Oscillation
400 W / π X (øD2 - ød2) π øD θ / 180 X 103 4 W øD c θ / 180 X 103 X (øD2 - ød2)
Plate P(kgf/㎠) V(m/min) PV(kgf/cm2·m/min)
Reciprocation 부싱 102 W / B X L 2 c S / 103 W c S / 5 X B X L
Item Unit Item Unit Item Unit
Inner diameter Ød mm Width B mm Stroke distance S mm
Outer diameter ØD mm Rotating speed n rpm Oscillating angle θ °
Length L mm Oscillating cycle c cpm Load W kgf