The selection of lubricating oil or grease for the industrial gearbox needs to be determined by the transmission structure design and working conditions of the industrial gearbox. for example gear geometry, material, circumferential speed/sliding speed, load conditions (torque/tooth surface pressure), energy consumption, working temperature, tooth surface heat dissipation, sealing conditions, and other factors.
First. What kind of lubricant oil or grease is used for different industrial gearbox
1. The foot-mounted cycloidal gear reducer adopts oil pool lubrication under normal conditions, and the oil level can be kept in the middle of the oil sight window. When the working conditions are harsh and the environment temperature is high, circulating lubrication can be used.
2. Cycloid pinwheel gear reducer generally chooses 40# or 50# mechanical oil lubrication at room temperature. In order to improve the performance of the reducer and prolong the service life of the cycloid pinwheel reducer, it is recommended to use 70# or 90# extreme pressure gear oil, the lubricating oil should be reconsidered when working under high and low-temperature conditions.
3. “If domestic reducer manufacturers can achieve 100% sealing, it is still recommended to use oil lubrication, because most companies have not been able to solve the sealing problem, so in general, RV series worm gearbox recommend 0# and 00# grease for sealing Better recommend 00#, almost recommend 0#, if it is a harmonic drive gear reducer, recommend 1# or 2#.
4. Gear reducers under heavy load conditions have more stringent requirements for lubricant oil. This requires lubricants to have excellent extreme pressure resistance and wear resistance. Lubricants containing specially formulated EP additives and anti-wear additives can better meet the lubrication requirements of the reducer under heavy load conditions.
5. When installing the vertical planetary cycloid reducer, prevent the oil pump from cutting off the oil to avoid damage to the parts of the reducer.
6. When refueling, you can turn the breather cap on the upper part of the seat to refuel. When draining the oil, turn the drain plug at the bottom of the main seat to drain the dirty oil. There is no lubricating oil inside the reducer at the factory.
7. The choice of lubricating oil or grease needs to be determined according to the transmission structure design and working conditions of the reducer. Such as gear geometry, material, peripheral speed/slip factors such as speed, load condition (torque/tooth surface pressure), energy consumption, working temperature, heat dissipation of tooth surface, sealing condition, and other factors. The right lubricant can not only provide long-term lubrication for the gear reducer sliding protection can also help equipment reduce wear, reduce noise, improve accuracy and reliability, and extend the service life of components. the first refueling operation for 100 hours should be replaced with new oil, and the internal dirty oil should be flushed out before continuous work. Replace every six months and adopt an 8-hour work system. If the working conditions are bad, the oil change time can be appropriately shortened. The practice has proved that the gearbox’s frequent cleaning and oil change (such as 3-6 months) play an important role in extending the service life of the gear reducer. Therefore, we should always add lubricating oil during use. In the long-term use of the gear reducer, attention should be paid to regular cleaning of the gear reducer, and the gear reducer is worn during use. The gearbox cleaning and maintenance machine uses the original oil supply and discharge system of the gearbox and the filtered old oil to realize the functions of cleaning the gearbox, quickly filtering waste oil, and filling new oil, helping the gear reducer to solve problems such as wear.
Second. Performance characteristics of gearbox lubricant
1. Good abrasion resistance
Wear resistance refers to the ability of the gear reducer lubricating oil to form and maintain an oil film on the friction surface between moving parts, prevent metal contact with each other, and reduce wear. The anti-wear properties of gear reducer lubricants mainly depend on oil properties and extreme pressure properties.
Oiliness refers to the performance of gear oil that can be adsorbed on the friction surface of the part to form an oil film to reduce and wear. Generally speaking, when we say that gear oil has good oiliness, it means that it has strong adsorption capacity and can improve the ability of wear resistance.
Extreme pressure refers to the ability to prevent sintering, bonding, and other damage to the friction surface under extremely high-pressure lubrication conditions where the contact pressure of the friction surface is very high and the oil film is prone to rupture. Ability also called carrying capacity.
2. Viscosity and viscosity-temperature
Gear reducer lubricants must have suitable viscosity and good viscosity-temperature properties.
Generally speaking, the use of high-viscosity lubricating oil is beneficial to prevent damage to mechanical parts and reduce noise, but low-viscosity lubricating oil is better in terms of transmission efficiency, cooling effect, and oil transmission.
Regarding viscosity-temperature performance, although gear reducer lubricating oil does not have the large temperature change of engine oil, it also requires good viscosity-temperature performance due to its high tooth surface pressure, especially when used in cold areas. Otherwise, wear will increase and fuel consumption will increase.
3. Oxidation stability
The gearbox’s lubricating oil is churned during gear movement and constantly in contact with oxygen. Various oxides are formed under the catalytic action of the metal, which makes the viscosity of the lubricating oil increase, the color becomes darker, the acid value increases, and the sediment increases, The color becomes darker, and causes corrosion to the machine parts, resulting in the deterioration of the anti-foam and oxidation resistance of the lubricant, and the lubricant has to be replaced. Lubricants with good oxidation stability have a long service life. Therefore, antioxidants are usually added to the lubricating oil to improve oxidation stability
4. Resistance and corrosion resistance
Rust prevention refers to the performance of the gearbox lubricant to prevent metal rust. Corrosion resistance refers to the performance of gear oil to prevent metal corrosion. The rust of metal parts is mainly caused by the presence of oxygen and water in the lubricant. The corrosion is caused by acid and sulfide in the oil. Usually, anti-corrosion additives and anti-corrosion additives are added to reducer lubricating oil to improve.
5. Foam resistance
The gearbox’s lubricating oil will produce many small bubbles under the intense stirring during the gear movement. If the small bubbles disappear quickly, it will not affect the use. If the stable foam does not disappear and emulsification occurs, the overflow will occur on the tooth surface, destroy the lubricant film, and increase wear.
Third, The gearbox lubricant oil selection principle
The primary factor in the selection of gear reducer lubricants is viscosity. Viscosity is a very important physical and chemical index of gear oil. Gear meshing speed is the main index for selecting viscosity. The proper viscosity of the gear motor’s gear oil can make the internal friction of the lubricating oil smaller, resulting in the gear surface damage, and the transmission noise and vibration are greatly reduced.
The gearbox’s viscosity lubricating oil is mainly realized by the base oil and the viscosity index improver. A good viscous agent not only requires high adhesion ability and good shear stability, but also requires good low-temperature performance and thermal oxidation stability. For viscous adhesives with poor shear stability, the main chain of the polymer is broken under shear stress, and the molecular weight decreases, which makes the oil thinner, which has a series of effects on wear and fuel consumption. For the same viscosity grade’s lubricating oils, if you choose non-refined base oils and poor viscosity indexing agents, although they can reach a certain viscosity standard after blending, they have poor viscosity-temperature properties and shear stability, The same viscosity can not reach the expected life cycle. Therefore, for low-speed and heavy-duty cement gear reducers, try to avoid using such lubricating oils, and choose high-quality high-quality lubricating oils, because their base oil and viscous agent are better.
The greater the viscosity of the gear oil, the stronger the protective ability to prevent various damages to the tooth surface, so the wear of the gearbox is smaller. If the viscosity is too large, the abrasive particles are not easy to precipitate, which reduces the washing effect and heat absorption cooling effect of the lubricating oil on the tooth surface, resulting in poor lubrication. At the same time, the abrasive particles suspended in the sleeve enter the meshing area, which easily causes abrasive particles to wear. In addition, excessive viscosity increases transmission resistance, increases tooth surface temperature, and increases power consumption. Generally speaking, when the viscosity increases by one grade, the energy consumption increases by about 1% to 5%, and the oil is stable and anti-emulsion
The chemical performance will decrease. However, high viscosity has obvious benefits for reducing noise and preventing oil leakage. In addition, equipment with uneven load, frequent startup, and working in a high-temperature environment should have a slightly higher viscosity. In summary, the industrial gearbox should use high-grade lubricating oil with suitable viscosity. For low-speed and heavy-duty large gear reducers, extreme pressure heavy-duty gear oils with high viscosity should be used as much as possible, because it has better extreme pressure anti-wear, thermal oxidation stability, anti-corrosion, and anti-corrosion properties than medium-duty gear oils. Rust and excellent anti-emulsification properties, so that it is easy to form a chemical film on the meshing surface of the gear, thereby protecting the surface of the gear tooth, and possibly reducing the wear of the gear reducer.
Forth, Gearbox lubricants oil precautions
1. The gearbox’s oil leakage is mainly related to three factors: on the one hand, it is the viscosity of the oil. The choice of oil viscosity is related to the viscosity of the gear reducer; the second is the sealing process of the gearbox, that is, the lip-shaped design of the sealing ring, including the rubber material, whether it is customized or standard, and whether it is suitable for the application conditions; The third is whether the oil is compatible with the sealing ring. Some materials such as NBR are compatible with mineral oil and PAO. If it is polyethylene glycol oil and PAG, it is incompatible. If it is not compatible, it will easily cause the rubber to crack.
2. If the oil content in the grease is too low, the thickener content will be very high, and the lubrication performance will not be so good, because when the wave generator and the RV wheel are running, there is some reflux, and too much thickener will cause It affects the fluidity of the oil. If the fluidity is very poor, it is difficult to return to the friction point. If the friction point is not returned, the gearbox will generate heat locally, and the heat will cause wear. Part of the lubricant will enter It will fail and turn black, causing a series of problems such as abrasive wear. If oil is used for lubrication, it can take away the local high temperature and wash away the basic particles at the friction point.
3. For the gearbox system with thin oil centralized lubrication, because the lubricating oil or the temperature of the oil tank has strict requirements, a cooler or a cooling coil is usually used to cool it. Although gear oils are required to have good anti-emulsification properties, after a considerable amount of water penetrates into the oil, it is easy to emulsify the oil. After the gear oils with extreme pressure, anti-wear agents are emulsified, the additives are hydrolyzed or precipitated and lose the original It has performance and produces harmful substances, which make gear oil rapidly deteriorate and lose its performance. Nippon New Energy reminds everyone that emulsified oil must never be used. For the water-cooled lubrication system, attention must be paid to prevent water leakage to avoid unnecessary damage to the reducer.
4. For a gearbox system that uses a pump for circulating lubrication, pay attention to the pressure difference of the pump and clean the filter in time. If the pressure difference of the pump is large in a short time, or the frequency of cleaning the filter screen increases significantly, and the oil sludge and metal shoulder on the filter screen increase significantly, it means that the lubricant is not in good condition in a certain sense. In addition to material and design issues, it can be said that the selection of lubricating oil is not reasonable enough: one is that the viscosity is not suitable, and the other is that heavy load can be used instead of medium load, that is, the higher grade gear oil is selected, and the effect will be significantly improved.
5. The mixing of new oil into old oil must be avoided, or the practice of adding high-viscosity oil in order to achieve a certain viscosity due to the decrease in viscosity. Doing so may have some short-term effects, but the performance of the oil will be significantly reduced, and the lubrication conditions of the equipment will become worse, resulting in increased wear and tear, which will shorten the service life of the equipment to a certain extent. In addition, it is possible that because of the different main agents, the additives “fight” when mixed, so that the effects of the additives cancel each other out, and the consequences for the equipment are unimaginable.
6. Regarding the oil change period, theoretically speaking, a short oil change period can better reduce friction loss and extend the service life of the equipment, while providing a necessary condition for ensuring its normal operation. But from the perspective of economic benefits, oil products should be used more accurately and effectively. Whether and when to change the oil, in addition to following the oil change period regulations, it should also be considered based on factors such as the operating time and operating rate of the equipment, so as to maximize the use of the oil.
7. The oil temperature, vibration, noise, and other issues of the oil equipment should be monitored regularly. When the tooth surface is damaged due to the deterioration of lubrication conditions, it can directly cause the vibration and noise to increase significantly.
You are welcome to consult us if your current industrial gearbox has a lubrication oil issue :