Lubrication

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OBJECT OF LUBRICATION

The lubrication method and the lubricant have a direct effect on the bearing life; the most suitable lubrication must therefore be selected for each application. Effects of lubrication are described as follows:

(1) DECREASE OF FRICTION AND ABRASION

It decreases rolling friction between the raceway and the rolling elements, sliding friction between rolling element and cage and sliding friction of guide surface between the cage and the bearing ring.

(2) REDUCTION OF HEAT GENERATION

It dissipates heat generated inside the bearing as well as heat conducted from the outside thus preventing overheating of the bearing and deterioration of the lubricant.

(3) PROTECTION FROM CORROSION AND CONTAMINANTS

It prevents corrosion of rolling elements, bearing rings and cages and also prevents the ingress of contaminants and moisture into the bearing.

REQUIRED CHARACTERISTICS OF THE LUBRICANT

  1. LOW FRICTION AND ABRASION
  2. HIGH STABILITY AGAINST HEAT, GOOD THERMAL CONDUCTIVITY
  3. STRONG OIL FILM
  4. NON-CORROSIVE
  5. PROVIDE A GOOD BARRIER AGAINST DUST AND MOISTURE
  6. MAINTAIN A STABLE VISCOSITY

LUBRICATION METHOD

There are two types of lubricant: oil or grease. It is important to select the correct lubricant and lubrication method for each application and its conditions.

LUBRICATING OIL AND GREASE

 LUBRICATING OILLUBRICATING GREASE
ROTATING SPEEDLOW MEDIUM HIGH SPEEDLOW MEDIUM SPEED
LUBRICANT EFFICIENCYEXCELLENTGOOD
COOLING EFFECTGOODNONE
TORQUECOMPARATIVELY LOWCOMPARATIVELY HIGH
LUBRICANT LIFELONGCOMPARATIVELY SHORT
LUBRICANT REPLACEMENTEASYDIFFICULT
LUBRICANT LEAKAGESHOULD NOT BE USED WHERE OIL LEAKAGE IS UNACCEPTABLELITTLE GREASE LEAKAGE
IMPURITIES FILTRATIONEASYDIFFICULT
SEALING EQUIPMENTCOMPLEXSIMPLE

GREASE FILLING VOLUME

SYMBOLFILLING VOLUME(%)OPERATING CONDITION
SPEEDLOAD
M70±10LOWHEAVY
S50±10LOWMEDIUM
G40±10MEDIUMMEDIUM
L30±10MEDIUMMEDIUM
Q25±5MEDIUMMEDIUM
K20±5HIGHLIGHT
X10±5HIGHLIGHT

NOTE: LIGHT LOAD ( 0.06Cr)
STANDARD LOAD ( 0.12Cr)


CRITERIA FOR LUBRICATING OIL SELECTION

OPERATING TEMPERATURE OF BEARING(°C)dnISO VISCOSITY GRADE OF
LUBRICATING OIL(VG)
MEDIUM LOADHEAVY LOAD/
SHOCK LOAD
-30~0UP TO PERMISSIBLE ROTATING SPEED15,22,3232,46
0~+60UP TO 1500032,46,68100
15000~8000032,4668
80000~15000022,3232
150000~5000001022,32
+60~+100UP TO 15000150220
15000~80000100150
80000~15000068100,150
150000~5000003268
+100~+150UP TO PERMISSIBLE ROTATING SPEED320

NOTE:

  1. IF HEAVY LOADS OCCUR AT LOW SPEEDS, A HIGHER VISCOSITY LUBRICATING OIL SHOULD BE USED.
  2. THIS TABLE IS FOR OIL BATH LUBRICATION SYSTEM AND RECIRCULATING OIL SYSTEMS.
  3. dn = BEARING BORE DIAMETER d(mm) ROTATING SPEED n(r.p.m)