The selection criteria for cylindrical gear reducer lubricating grease mainly consider the following aspects:
1. Load pressure : Select based on the actual working load and pressure of the gear. For heavy-load cylindrical gear reducers, greases with high base oil viscosity and high thickener content should be selected, and greases containing extreme pressure additives or fillers (such as molybdenum disulfide or graphite) should also be selected; for gears with medium and low loads, greases with short fiber structure of No. 2 consistency soap fibers and medium viscosity base oil should be generally selected.
2. Temperature characteristics :
High temperature environment : If the reducer works in a high temperature environment, the grease must have high temperature resistance. You should choose greases with high drop point, good oxidation resistance and small evaporation losses, such as composite lithium-based grease, polyurea grease, etc. Generally speaking, the maximum service temperature should be lower than the drop point by 10-20℃ (mineral oil-based grease) or 20-30℃ (synthetic grease).
Low-temperature environment : In low-temperature environment, lipids with good low-temperature fluidity, low starting torque and similarly low viscosity should be selected, such as lipids based on synthetic oil, so that they can quickly reach various lubricating parts and play a role at low temperatures.
3. Speed :
High-speed operation : For high-speed operation cylindrical gear reducers, in order to reduce viscous friction resistance and temperature rise, grease with a larger cone degree made of low-viscosity base oil should be used.
Low-speed operation : Low-speed gears can choose high-cone grade grease made of high viscosity base oil.
4. Working environment :
Humid environment : If the reducer works in a humid environment or may be exposed to water, it is necessary to choose greases with good water resistance and rust resistance, such as calcium-based grease, composite calcium-based grease, lithium-based grease, etc.
Dust environment : In a dusty working environment, in order to prevent dust from entering the gear meshing area and aggravation, grease with strong adhesion and not easily contaminated should be selected, and it is best to have a good sealing property. Grease with a smaller needle inlet can be selected.
Environments with chemical corrosion risks : When corrosive gases or media are present around, grease containing anti-corrosion additives should be used to protect the surface of the gear from corrosion.
5. Gear material : If it is an ordinary metal gear, grease that meets load, temperature and other requirements is just fine; if it is a special material gear, such as plastic gear, the compatibility of the grease and the material should also be considered to avoid corrosion or swelling. A lithium soap thickener that is well compatible with most plastics can be used to thicken the ultra-high viscosity synthetic oil, and grease with antioxidant and corrosion-resistant additives.
6. Properties of grease :
Extreme pressure and wear resistance : The gears bear high pressure and friction during meshing. The grease must have good extreme pressure and wear resistance, which can form a strong oil film on the tooth surface, effectively reduce wear between the gears, and prevent failure forms such as tooth surface glue and abrasion.
Antioxidant : During long-term use, grease will oxidize due to factors such as contact with air and heating, so it needs to have good oxidation resistance to prolong service life and reduce harmful substances such as sludge and carbon deposits caused by oxidation.
Mechanical stability : refers to the ability of the grease to maintain its structure and performance when it is subject to mechanical shearing. Good mechanical stability ensures that the grease will not be easily damaged due to mechanical forces during gear operation, and maintains a good lubricating state.
Noise reduction performance : Lubricating grease with good shock absorption performance can reduce the noise generated when gears are meshed and make the reducer run more smoothly. This performance is more important in some occasions where noise requirements are high.
7. Lubrication method : If a circulating lubrication system is used, the grease is required to have good fluidity and filterability to ensure smooth passage through the pipes and filters; if lubrication is applied or lubrication is used, the adhesion of the grease is higher, ensuring that it can adhere to the gear surface better.
8. Maintenance cycle : Determine the grease replacement cycle according to the frequency of the reducer and the working environment. For some occasions where frequent maintenance is difficult, greases with a long service life should be selected; in the case of high frequency of use and harsh working environment, it may be necessary to shorten the maintenance cycle and choose greases with better performance.
