Lubrication
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 CHARACTERISTIC OF THE LUBRICANT
- LOW FRICTION AND ABRASION
- HIGH STABILITY AGAINST HEAT, GOOD THERMAL CONDUCTIVITY
- STRONG OIL FILM
- NON-CORROSIVE
- PROVIDE A GOOD BARRIER AGAINST DUST AND MOISTURE
- MAINTAIN A STABLE VISCOSITY
LUBRICATION METHOD
There are two types of lubricant: oil and grease. It is important to select the correct lubricant and lubrication method for each application and its conditions.
LUBRICATING OIL AND GREASE
| LUBRICATING OIL | LUBRICATING GREASE | |
|---|---|---|
| ROTATING SPEED | Low - Medium - High speed | Low - Medium speed |
| LUBRICANT EFFICIENCY | Excellent | Good |
| COOLING EFFECT | Good | None |
| TORQUE | Comparatively low | Comparatively high |
| LUBRICANT LIFE | Long | Comparatively short |
| LUBRICANT REPLACEMENT | Easy | Difficult |
| LUBRICANT LEAKAGE | Should not be used where oil leakage is unacceptable | Little grease leakage |
| IMPURITIES FILTRATION | Easy | Difficult |
| SEALING EQUIPMENT | Complex | Simple |
GREASE FILLING VOLUME
| SYMBOL | FILLING VOLUME(%) | OPERATIVE CONDITION | |
|---|---|---|---|
| SPEED | LOAD | ||
| M | 70±10 | LOW | HEAVY |
| S | 50±10 | LOW | MEDIUM |
| G | 40±10 | MEDIUM | MEDIUM |
| L | 30±10 | MEDIUM | MEDIUM |
| Q | 25±5 | MEDIUM | MEDIUM |
| K | 20±5 | HIGH | LIGHT |
| X | 10±5 | HIGH | LIGHT |
note:
Light load: ≤ 0.06Cr
Standard load: ≤ 0.12Cr
CRITERIA FOR LUBRICATING OIL SELECTION
| OPERATING TEMPERATURE OF BEARING (°C) | dn | ISO VISCOSITY GRADE OF LUBRICATING OIL (VG) | |
|---|---|---|---|
| MEDIUM LOAD | HEAVY LOAD / SHOCK LOAD | ||
| -30~0 | up to permissible rotating speed | 15,22,32 | 32,46 |
| 0~+60 | up to 15000 | 32,46,68 | 100 |
| 15000~80000 | 32,46 | 68 | |
| 80000~150000 | 22,32 | 32 | |
| 150000~500000 | 10 | 22,32 | |
| +60~+100 | up to 15000 | 150 | 220 |
| 15000~80000 | 100 | 150 | |
| 80000~150000 | 68 | 100,150 | |
| 150000~500000 | 32 | 68 | |
| +100~+150 | up to permissible rotating speed | 320 | |
note:
- If heavy loads occur at low speeds, a higher viscosity lubricating oil should be used.
- This table is for oil bath lubrication system and recirculating oil systems.
- dn = bearing bore diameter d(mm) × rotating speed n(rpm).
LUBRICANT
Usually, open bearings are lubricated in advance with Jinzhi Hangu 2; bearings with shields are usually greased with Jinzhi Hangu 2.
Bearings can be lubricated with other lubricants as follows:
| COMMON GREASE BRANDS AND EFFICIENCY | |||||
|---|---|---|---|---|---|
| MANUFACTURER | BRAND | CODE | OPERATING TEMPERATURE | APPROVED STANDARD | |
| °C | °F | ||||
| Shell | Alvania RS | AV 2 | -25/+120 | -13/+248 | - |
| Aeroshell N° 6 | AG 6 | -40/+120 | -40/+248 | MIL-G-7711 A | |
| Aeroshell N° 7 | AG 7 | -70/+150 | -94/+302 | MIL-G-23827 A | |
| Aeroshell N° 15 A | AG 5 | -70/+230 | -94/+446 | MIL-G-25103 D | |
| Aeroshell N° 16 | AG 16 | -55/+200 | -67/+392 | MIL-G-25760 A | |
| Exxon (Esso) | Beacon 325 | B 32 | -55/+120 | -67/+248 | MIL-G-3278 A |
| Andok C | AKC | -25/+120 | -13/+248 | ||
| Andok B | AKB | -30/+110 | -22/+230 | MIL-G-18709 A | |
| Klüber | Isoflex Super LDS 18 | ISF 1 | -60/+130 | -76/+266 | MIL-G-3278 A / MIL-G-7118 A |
| Isoflex LDS 18 Spec. A | ISF 2 | -60/+130 | -76/+266 | MIL-G-23827 A / MIL-G-15793 | |
| Isoflex Alltime SL 1 | ISF 3 | -70/+150 | -94/+302 | ||
| Isoflex Alltime SL 2 | ISF 4 | -50/+150 | -58/+302 | ||
| Isoflex NBU 15 | ISF 5 | -40/+130 | -40/+266 | MIL-G-771 A / MIL-G-25760 | |
| Isoflex PDB 38/CX2000 | ISF 6 | -70/+120 | -94/+248 | ||
| Isoflex Topas NB 52 | ISF 7 | -60/+160 | -76/+320 | MIL-G-81322 C | |
| Unisilicon TK 44-N2 | TK 44-N2 | -60/+230 | -76/+446 | ||
| Staburags NBU 12 | NBU 12 | -35/+150 | -31/+302 | ||
| Mobil | Mobil Grease 28 | MG 28 | -60/+75 | -76/+347 | MIL-G-81322 A |
| Chevron | Chevron SRI 2 | SRI | -30/+175 | -22/+347 | |
| Texaco | Low Temp EP | LTEP | -70/+120 | -94/+248 | MIL-G-23827 A |
| Unitemp Grease 500 | UT 500 | -54/+177 | -65/+350 | ||
| Dow Corning | DC 33 | DC 33 | -70/+180 | -94/+356 | MIL-G-46886 |
| DC 44 | DC 44 | -40/+200 | -40/+392 | MIL-G-15719 A | |
| Du Pont | Krytox 240 AB | K 240 AB | -40/+227 | -40/+440 | MIL-G-38220 |
| Krytox 240 AC | K 240 AC | -34/+288 | -30/+550 | MIL-G-27617 A | |
| Gen. Electr. | Versilube G 300 | VG 300 | -70/+230 | -94/+446 | |
| Jinzhi | Hangu 2 | HG 2 | -20/+120 | -4/+248 | |
| COMMON OIL BRANDS AND EFFICIENCY | |||||
|---|---|---|---|---|---|
| MANUFACTURER | BRAND | CODE | OPERATING TEMPERATURE | APPROVED STANDARD | |
| °C | °F | ||||
| Shell | AeroShell Fluid3 | AF 3 | -56/+115 | -70/+240 | MIL-L-7870 A |
| AeroShell Fluid12 | AF 2 | -60/+120 | -76/+248 | MIL-L-6085 A | |
| Klüber | Isoflex PDB 38 | PDB 38 | -70/+120 | -94/+248 | MIL-L-6085 A |
| Dow Corning | DC 550 Fluid | DC 550 F | -40/+230 | -40/446 | |