Gear Transmission and Industrial Gear Lubricating Oil
I. Characteristics of Gear Transmission
(1) High Transmission Efficiency
Gear transmission demonstrates outstanding efficiency among various mechanical transmission forms, typically reaching 95% - 99%. This is mainly attributed to its direct meshing transmission mode. During the power transmission process, energy loss mainly occurs in links such as tooth surface friction and bearing operation friction. Compared with transmission methods like belt drive, gear transmission has no slipping phenomenon, effectively reducing energy loss, making the power transmission more efficient, and giving full play to the efficiency of the power source, significantly reducing energy consumption costs in industrial production.
(2) Stable Transmission Ratio
Once the module and number of teeth of the gear are determined, its transmission ratio is fixed and is not affected by fluctuations in working conditions. This characteristic of a stable transmission ratio makes gear transmission the first choice for equipment with strict requirements for the accuracy of the speed ratio. For example, in the transmission system of precision machine tools, the stable transmission ratio ensures the precise motion relationship between the cutting tool and the workpiece, thus ensuring the consistency and stability of machining accuracy and providing a solid guarantee for the production of high-quality components.
(3) Reliable Operation and Long Service Life
A gear transmission system that has undergone scientific design and precise manufacturing has a high degree of reliability and a long service life under normal operating conditions that meet the working conditions. Its structure is compact and it can withstand large loads. This is because gear materials mostly use high-strength alloy steel and are subjected to heat treatment processes such as quenching and carburizing, which greatly improves the surface hardness and wear resistance of the teeth. At the same time, reasonable tooth shape design and lubrication measures further extend the service life of the gears, reduce the frequency of equipment maintenance and replacement, and lower production operation costs.
(4) Wide Application Range
Gear transmission has extremely strong adaptability and can operate under various different working conditions. Whether it is the low-speed and heavy-load machinery in the metallurgical and mining industries or the high-speed and light-load aerospace equipment, a suitable gear transmission solution can be found. Moreover, it is not only suitable for the transmission between parallel shafts but also widely used in the transmission between intersecting shafts (such as bevel gear transmission) and non-parallel, non-intersecting shafts (such as worm and worm gear transmission), meeting the diverse transmission requirements of complex mechanical systems and becoming an essential key transmission component in modern mechanical equipment.
II. Characteristics of Closed Gear Lubrication
(1) Diverse Lubrication Methods
The common lubrication methods for closed gear transmission mainly include oil bath lubrication and oil injection lubrication. Oil bath lubrication is simple to operate and has a low cost. Part of the gear is immersed in the oil sump, and when the gear rotates, it will carry the lubricating oil to the tooth surface for lubrication. It is suitable for working conditions with a circumferential speed generally lower than 12 - 15m/s. Oil injection lubrication, on the other hand, uses an oil pump to spray the lubricating oil onto the tooth surface at a specific pressure. This method is suitable for occasions with a higher circumferential speed, which can quickly and effectively deliver the lubricating oil to the tooth surface. At the same time, it can also play a good cooling role on the tooth surface, effectively reducing the tooth surface temperature and reducing thermal deformation and wear.
(2) High Requirements for the Cleanliness of Lubricating Oil
Since the closed gearbox is a relatively closed space, the lubricating oil is recycled in the box. If impurities such as metal debris and dust are mixed into the lubricating oil, it will intensify the wear of the tooth surface during the gear meshing process and greatly shorten the service life of the gear. Therefore, a high-precision filter is usually installed in the lubricating oil circuit of the closed gear transmission system to strictly filter the lubricating oil, ensure its cleanliness, maintain a good lubrication state, and ensure the smooth operation of the gear transmission.
(3) Good Sealing Performance
In order to prevent the lubricating oil from leaking and causing lubrication failure, as well as prevent external impurities, moisture, etc. from invading and contaminating the lubricating oil, the closed gearbox must have good sealing performance. Usually, a variety of sealing methods such as sealant and sealing rings are used to effectively seal each joint surface of the gearbox, the shaft extension, and other parts where leakage may occur, maintain the normal liquid level and quality of the lubricating oil in the box, and ensure that the gear transmission system works in a clean and stable lubrication environment.
III. Characteristics of Open Gear Lubrication
(1) Harsh Lubrication Conditions
Open gears are directly exposed to the external environment and are easily contaminated by dust, moisture, impurities, etc. At the same time, the heat dissipation conditions are poor, and the tooth surface temperature is relatively high during operation, making lubrication more difficult. These unfavorable factors make the wear rate of open gears relatively fast, and the requirements for lubrication are more urgent and special.
(2) Mostly Use High-viscosity Lubricants
In order to maintain a good lubrication effect under harsh working conditions, open gears usually use high-viscosity lubricants. High-viscosity lubricants can form a relatively thick oil film on the tooth surface to resist the invasion of external impurities. At the same time, they have good adhesion and are not easily thrown off or washed away, thus providing long-lasting lubrication protection for the gears.
(3) Regular Manual Smearing or Spraying Lubrication
Due to the structural characteristics of open gears, it is difficult to achieve automatic circulating lubrication like that of closed gears. Generally, the method of regularly manually smearing or spraying lubricants is used for lubrication. This lubrication method requires strict operation according to the specified time interval and lubricant dosage to ensure that the gears are always in a good lubrication state. At the same time, it also puts forward high requirements for the professional skills and sense of responsibility of the operators.
IV. Classification of Gear Oil
Classification Criteria
The GB/T7631.7-1995 gear oil classification standard is formulated by equivalently adopting ISO/6743-6:1990. It is divided into industrial closed gear oil, industrial open gear oil, and vehicle gear oil.
Industrial Gear Oil
-Purpose: It is mainly used for the gears of industrial equipment. It is formulated from base oil and additives.
-Base Oil: Mostly paraffin-based base oil, blended with heavy bright oil and light neutral oil.
-Additives: Viscosity index improver, demulsifier, pour point depressant, antifoaming agent, friction modifier, extreme pressure anti-wear agent, antioxidant, rust inhibitor, antioxidant, etc.
Industrial Closed Gear Oil
-Lubrication Occasion Classification: It is divided into continuous lubrication and continuous splash lubrication occasions.
-Continuous Lubrication Varieties (Splash, Circulation or Spray): CKB, CKC, CKD, CKE, CKS, CKT (The introduction of the letter "K" in the second letter is to avoid confusion with diesel engine oil).
-Continuous Splash Lubrication Variety: CKG
-Characteristics of CKB: Refined mineral oil, with anti-oxidation, anti-corrosion (for ferrous and non-ferrous metals) and anti-foaming properties.
-Characteristics of CKC: On the basis of CKB oil, its extreme pressure and anti-wear properties are improved.
-Characteristics of CKD: On the basis of CKC oil, its thermal/oxidative stability is improved, and it can be used at higher temperatures.
-Characteristics of CKE: On the basis of CKB oil, it has a low friction coefficient.
-Characteristics of CKS: A lubricant with anti-oxidation, anti-friction and anti-corrosion (for ferrous and non-ferrous metals) properties, used under extremely low and extremely high temperature conditions.
-Characteristics of CKT: A CKS-type lubricant under extremely low and extremely high temperatures and heavy loads.
-Characteristics of CKG: A grease with extreme pressure and anti-wear properties.
Industrial Open Gear Oil
-GB/T 7631.7-1995 Classification: For industrial open gears equipped with safety baffles, with intermittent or immersion or mechanical application, it is divided into three varieties: CKH, CKJ, and CKL; for intermittent application, it is divided into one variety: CKM.
-Characteristics of CKH: Usually an asphalt-type product with anti-corrosion properties.
-Characteristics of CKJ: On the basis of CKH-type products, its extreme pressure and anti-wear properties are improved.
-Characteristics of CKL: A grease with improved extreme pressure, anti-wear, anti-corrosion and thermal stability.
-Characteristics of CKM: A product that is allowed to be used under extreme loads, with improved anti-scuffing properties and anti-corrosion properties.
V. What is Industrial Gear Oil
Industrial gear oil is a lubricating oil specifically designed for various industrial gear transmission devices. Its base oil is usually composed of mineral oil, synthetic oil, or a mixture of the two. Mineral oil has a wide source and low cost, and it has certain lubricating properties. Synthetic oil, on the other hand, performs more excellently in terms of high and low-temperature performance, oxidation resistance, anti-wear performance, etc., and is suitable for gear transmission systems with complex working conditions and stringent requirements. In addition, various functional additives are added to industrial gear oil to meet the lubrication needs of gear transmission under different working conditions. It is a key lubricating material to ensure the normal operation of industrial gear equipment.
VI. Functions of Industrial Gear Oil
(1) Lubrication and Friction Reduction
During the gear meshing process, industrial gear oil forms an oil film between the tooth surfaces, separating the metal surfaces, which greatly reduces the friction coefficient between the tooth surfaces, reduces wear and energy loss, and makes the gear transmission smoother and more efficient.
(2) Cooling and Heat Dissipation
Gears generate heat due to friction during operation. Industrial gear oil can absorb and carry away this heat, and dissipate the heat through the circulating cooling system, effectively reducing the working temperature of the gears, preventing the occurrence of failure forms such as tooth surface scuffing and annealing caused by overheating, and extending the service life of the gears.
(3) Rust Prevention and Corrosion Protection
The rust inhibitors and anti-corrosion agents in industrial gear oil can form a protective film on the gear metal surface, preventing moisture, oxygen, and other corrosive media from coming into contact with the metal, preventing the gears from rusting and corroding, and ensuring that the gears can still maintain good performance in harsh working environments.
(4) Cleaning and Dispersion
The detergents and dispersants in industrial gear oil can disperse the wear particles, impurities, etc. generated during the gear operation in the oil, preventing them from accumulating on the tooth surface and avoiding abrasive wear. At the same time, these impurities are filtered out through the filter to maintain the cleanliness and lubricating performance of the lubricating oil.
VII. Lubrication Requirements of Industrial Gear Oil
(1) Appropriate Viscosity
Viscosity is one of the important performance indicators of industrial gear oil. It is necessary to select gear oil with an appropriate viscosity according to the type of gear and working conditions (such as rotational speed, load, temperature, etc.). If the viscosity is too low, the oil film thickness is insufficient, making it difficult to effectively bear the load, and it is easy to cause tooth surface wear and scuffing. If the viscosity is too high, it will increase the power loss and starting resistance, and at the same time affect the fluidity and heat dissipation effect of the lubricating oil. Generally speaking, high-viscosity gear oil should be selected for low-speed, heavy-load, and high-temperature working conditions, while low-viscosity gear oil is suitable for high-speed, light-load, and low-temperature working conditions.
(2) Good Anti-wear Performance
During the gear meshing process, the tooth surfaces bear relatively large pressure and friction force, and are prone to wear. Therefore, industrial gear oil must have good anti-wear performance, be able to form a tough protective film on the tooth surface, effectively resist wear, and ensure the normal meshing and service life of the gears.
(3) Excellent Oxidation Resistance
During the gear transmission process, the lubricating oil will oxidize and deteriorate due to factors such as contact with air, heating, and metal catalysis. After oxidation, the viscosity of the gear oil increases, the acid value rises, and precipitation and paint film will be generated, reducing the lubricating performance and even corroding the gears. Therefore, industrial gear oil needs to have excellent oxidation resistance and be able to maintain stable chemical properties and lubricating performance for a long time.
(4) Demulsibility
When the gear oil comes into contact with water, it should have good demulsibility and be able to quickly separate the water to avoid the formation of an emulsion. The lubricating performance of the emulsified gear oil drops significantly, and it is easy to cause metal corrosion and increased wear. Therefore, the demulsibility is particularly important for gear transmission systems that work in humid environments or may come into contact with water.
VIII. Selection of Industrial Gear Oil Additives
(1) Anti-wear Additives
Anti-wear additives are an essential component of industrial gear oil. Common types include sulfur-phosphorus type, sulfur-nitrogen type, etc. Sulfur-phosphorus anti-wear additives can chemically react with the tooth surface metal under high temperature and high pressure to form a chemical reaction film, effectively reducing the friction coefficient of the tooth surface and reducing wear. When selecting anti-wear additives, it is necessary to make a reasonable combination according to the working conditions and load conditions of the gears to ensure good anti-wear protection under different working conditions.
(2) Extreme Pressure Additives
Extreme pressure additives are mainly used to meet the gear lubrication requirements under extreme working conditions such as heavy load and impact load. Commonly used extreme pressure additives include chlorine-containing, phosphorus-containing, sulfur-containing compounds, etc. These additives can chemically react with the tooth surface metal under extreme pressure conditions to generate a reaction film with low shear strength, preventing tooth surface scuffing and galling. When selecting extreme pressure additives, it is necessary to fully consider their compatibility with the base oil and other additives, as well as their impact on the environment.
(3) Antioxidant Additives
Antioxidant additives can inhibit the oxidation process of gear oil and extend its service life. Common antioxidant additives include phenolic types, amine types, etc. Phenolic antioxidant additives have good antioxidant effects and thermal stability, and are less toxic. Amine antioxidant additives have more prominent antioxidant performance at high temperatures. In practical applications, phenolic and amine antioxidant additives are usually used in combination to achieve the best antioxidant effect.
(4) Rust Inhibitor Additives
The function of rust inhibitor additives is to prevent the gear metal from rusting. Commonly used rust inhibitor additives include petroleum sulfonates, fatty acids and their soaps, etc. These additives can form an adsorption film or a chemical reaction film on the metal surface, preventing moisture and oxygen from coming into contact with the metal, thus playing a rust prevention role. When selecting rust inhibitor additives, it is necessary to consider their rust prevention effect under different environmental conditions and their compatibility with other additives.
(5) Anti-foam Additives
Anti-foam additives are used to eliminate the foam generated during the circulation of gear oil. The presence of foam will affect the normal circulation and lubrication effect of the lubricating oil, reduce the oil film strength, and lead to increased tooth surface wear. Silicone-based anti-foam additives are commonly used anti-foaming agents, which can reduce the surface tension of the foam and make the foam break quickly. When adding anti-foam additives, it is necessary to pay attention to controlling the addition amount to avoid affecting other properties of the gear oil due to excessive addition.
The Price of Additive Packages
The price of Additive Packages varies depending on factors such as brand, specification, composition, and sales channels. If you are interested in Additive Packages, please feel free to contact us.
Supplier of Additive Packages
UNPChemicals is a professional supplier of high-quality and effective Additive Packages. We offer several remarkable products, namely High zinc hydraulic oil additives UNP AH502A,Low Zinc Hydraulic Oil Additives UNP AH502B,Zinc-free Hydraulic Oil Additives UNP AH502C,etc.
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Professional Lubricant Additive Manufacturer
UNPChemicals, aka Luoyang Pacific United Petrochemical Co., Ltd., focuses on the application and development of special lubricating grease additives such as MODTC, MODTP, molybdenum amide, thiadiazole metal deactivators, and phosphate esters. With nearly 30 products in seven series, including extreme pressure anti-wear additives and special grease additives, it is a global manufacturer of special lubricating grease additives and a national high-tech enterprise with great influence and leading role in the industry. If you are looking for Lubricant Additiveor technical information, feel free to contact UNPChemicals.