Grease Concept
Grease is a semi-solid or solid substance formed by dispersing a thickener in lubricating oil.
Translation
Other components with special properties may also be added depending on different conditions.
Classification of Lubricants
Classified by form, grease is categorized as a semi-solid lubricant, as shown in the table below:
| Form | Category |
| Liquid lubricant | Lubricating oil |
| Semi-solid lubricant | Grease, synthetic grease |
| Solid lubricant | Molybdenum disulfide, graphite, etc. |
Grease Lubrication vs. Oil Lubrication
Both grease lubrication and oil lubrication have their own advantages and disadvantages, as shown in the table below:
| Advantages and Disadvantages of Grease Lubrication and Oil Lubrication | Grease Lubrication | Oil Lubrication |
| Oil supply method | Long-term relubrication-free based on bearing sealing | Continuous oil supply required at lubrication points (drip, splash, circulation, etc.) |
| Required oil volume | Minimum necessary volume can be limited | Large volume required |
| Lubrication system | Simple | Complex |
| Leakage | Almost no risk of leakage due to the self-sealing effect of grease | Leakage may occur if sealing is inadequate |
| High-speed operation suitability | Limited | Applicable |
| Impurity removal | Not possible | Continuous removal via filtration and centrifugal separation |
| Cooling capacity | No cooling capacity | Excellent cooling capacity |
| Friction loss | Generally high; however, it can reduce torque for operating bearings due to channeling | Generally low |
Consistency of Grease
Consistency is a basic physical property indicating the hardness of grease; the higher the thickener content, the greater the grease consistency.
Grease is graded by different worked penetration grades according to its hardness, as shown in the table below:
| Consistency Grade | Penetration Range | State | Hardness |
| Grade 000 | 445–475 | Liquid | Soft → Hard |
| Grade 00 | 400–430 | Semi-fluid | |
| Grade 0 | 355–385 | Extra soft | |
| Grade 1 | 310–340 | Very soft | |
| Grade 2 | 265–295 | Soft | |
| Grade 3 | 220–250 | Slightly hard | |
| Grade 4 | 175–205 | Hard | |
| Grade 5 | 130–160 | Very hard | |
| Grade 6 | 85–115 | Extra hard |
