Lubrication

Lubricant selection is of critical importance for the performance of a ball bearing. It affects Life, Torque, Speed, Noise, Grease migration, Outgassing, Temperature effects and rust prevention. In most cases NMB supplies ball bearings as a complete unit, pre-lubricated with grease. It is not normal to re-lubricate ball bearings as they are "sealed for life".

The two basic types of lubricants available are oil and grease.

Applications that require extremely low torque or narrow range of torque variation, are suited to use oil as a lubricant.

Depending on the application, it is possible that an oil lubricant may not meet a specific requirement. Please contact to NMB for the proper oil selection.

Greases are comprised of a base oil and a thickener.

The life obtained from greases is considerably greater than that of just oil. This is because of a continuous mechanism of lubrication by base oil separation coming from the construction of the thickener.

Lubricant Fill Amount

The standard lubricant fill amount for small and miniature size bearings is 30 %. Grease fill amount varies in each application, and is specified as follows.
Fill amount symbols Fill amount Fill amount symbols Fill amount
X 5 ~ 10% No code (standard) 25 ~ 35%
L 10 ~ 15% H 40 ~ 50%
T 15 ~ 20% J 50 ~ 60%

 

 

Performance Characteristics of Grease

Name Lithium soup grease   Urea grease   Fluornated grease
Thickener Lithium soup Urea PTFE
Base Oil Major Component Ester Synthetic hydrocarbon Ester Fluorinated
Noise ◯ (△) ◯ (△)
Torque ◎◎
High temperature ◎◎ ◎◎ ◎◎
Low temperature ◯ (△) ◎◎
High Speed
plastic degradation × × × × - -
conductivity - - - - - - - -
low dust × × × - - - -
price × × ×
code LY121 LY72 LY552 LY551 LY532 LY500 LY586 LY699
Characteristic general low torque wide range heat resistance, high speed heat resistance, high speed heat resistance heat resistance heat resistance
base oil viscocity
mm3/S@40℃
representing value 26 15 55 48 100 190 85 210
cone penetration representing value 250 275 240 225 255 280 280 280
application temperature range* -50~
+150
-50~
+150
-40~
+130
-40~
+200
-40~
+180
-50~
+260
-50~
+220
-40~
+200
Name Fluornated grease   Conductive grease   Oil
Thickener PTFE carbon -
Base Oil Major Component Fluorinated + Ester Synthetic hydrocarbon Fluorinated Ester Synthetic hydrocarbon
Noise × × ×
Torque ×
High temperature ◎◎ ◎◎
Low temperature △ (◯)
High Speed
plastic degradation - - ×
conductivity - ◎◎ - -
low dust - - - - × ×
price ×
code LY655 LY727 LY722 LY707 LO1 LY650
Characteristic heat resistance conductivity conductivity conductivity, heat resistance low torque plastic resistance
base oil viscocity
mm3/S@40℃
representing value 85 148 20 420 12 32
cone penetration representing value 280 235 263 230 - -
application temperature range* -50~
+200
-40~
+125
-40~
+125
-30~
+250
-50~
+120
-40~
+130
* These ranges are based on the information given by each grease manufacturer. Please note that they are not the specific temperature ranges for bearing application.

Grease additives include rust inhibitors, EP (extreme pressure) additives, oxidation preventatives, etc. Because of the wide variety and complexity of additives, the characteristics of similar greases change considerably from one manufacturer to another.

Calculating grease life and performance in sealed-for-life ball bearings includes many complicated factors, such that grease life calculation formulas in the industry at this time will likely show different results than actual life.

In recent years, using plastic material around the bearing has become more common, so the proper selection of lubricant is even more critical to prevent compatibility issues.




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