|
| Relubrication |
Home >> Technical Support >> Care and Maintenance of Bearings |
In grease lubrication, the lubricating characteristic of grease deteriorates
with operating hours, thus requiring relubrication of the bearing at
appropriate intervals. Relubrication intervals of grease depend on the
type, dimensions, and speed of the bearing, and the type of grease.
A line diagram serving as a rough guide of grease relubrication intervals,
is given in the bearing section of the NTN general catalog.
For oil lubrication, oil changing intervals depend on the operating
condition of the machine and the type of lubrication system (a rough
guide to oil changing intervals and for oil analysis intervals is given
in Tables 1 and 2) .
Table 1: Lubrication Oil Properties and Serviceable Limits
| Property |
Serviceable limit |
Remarks |
| Circulating oil |
Gear Oil |
| Viscosity Deterioration mm2/s |
Less than 10% |
25% max., 10 to 15% is preferble |
Caused by oxidation or mixing with different
type of oil |
| Water content volume % |
0.2 max. |
0.2 max. |
May be reusable after water removal |
| Insoluable matter Nomal¡¡in weight
Pentane |
Nomal
Pentane % |
0.2 max.
|
0.2 max.
|
Additive carbon particles |
| Benzene % |
0.9 max. |
0.5 max. |
Dust |
| Sedimentation value ml/10ml |
0.1 max. |
|
Contaminants such as water and dust, or worn
metal particles |
| Total acid value KOH mg/g |
2 to 3 times that of new oil |
Adopt higher value according to additives |
| Ash % |
- |
0.2 max. |
|
| Iron content in ash % |
- |
0.1 max. |
|
Table 2: Frequency of Lubricating Oil Analysis
| Lubrication system |
Inspection interval |
| Normal operating conditions |
* Severe operating conditions |
| Disk lubrication method |
One year |
6 months |
| Oil bath or splash lubrication |
6 months |
3 months |
| Circulating lubrication |
9 months |
1 to 3 months |
*Severe operating conditions means:
- Severe water condensation or ingress.
- Excessive ingress of dust, gas, etc.
- Operating temperature exceeding 120 °C.
|
