Low temperature lubricating oils. Low temperature bearing grease

Bearings provide movement in mechanisms. With their help, the elements of the system slide. For a long and high-quality functioning of the parts, they must be properly cared for. Lubrication for bearings is one of the main elements that ensure their movement. How to choose the right sliding substance should be studied before servicing the elements of the mechanism.

Bearing lubrication functions

Lubrication is used for a specific purpose. The main functions of the substance can be called the following:

• reduction of friction between the constituent parts of the part;
• an increase in the sliding of surfaces as a result of their deformations when a load occurs;
• forming a layer, grease for bearings reduces the impact of parts of the part during operation, prolonging their durability;
• allows you to evenly distribute the heat generated by the friction of the constituent elements against each other;
• performs the function of a coolant at elevated operating temperatures;
• corrosion protection;
• Prevents dust and dirt from getting inside the part.

In order for grease for bicycle, automotive bearings, as well as in electric motors and other systems to perform all of the listed functions, it is necessary to take into account the conditions for using the part.

Temperature regime

At low temperatures, high-temperature bearing grease crystallizes and thickens. A substance not designed for operation with high heating will coke and dry out.

Therefore, when using an agent for a motor, such as an electric motor, it is necessary to use paste-like agents. They will ensure the normal operation of the system at temperatures from +200 to +1000 degrees. Before raising this indicator to the line of +280 degrees, high-temperature lubricants, like a paste, act as an anti-seize coating. This protects the part from jamming.

For part operation in the range from -30 to +120 degrees, the best bearing grease will have a mineral base.

At temperatures from -40 to -70 degrees, silicone products should be used to slide the elements of parts. In everyday life, they are used less frequently than the two previous options.

Temperature is far from the only factor that is taken into account when choosing a sliding agent. Which one is better to choose will tell you the speed of the part, the type of medium and the load acting on the system.

Rotation, loads and bearing environment

When the speed limit for which the lubricant is designed is reached, it will spread to the edges. Inside, the part begins to dry out.

The speed limit is set individually for a medium such as bearing grease. Which is better should be determined based on this indicator. Synthetic agents are used for high-speed mechanisms.

Negative factors affecting the sliding substance should be considered when choosing the best bearing grease. Water, dust, acid or steam will affect it.

For maintenance of equipment used under the influence of acids, solvents, preference should be given to products that are resistant to such influences.

For example, bicycle bearing grease must be resistant to a large number moisture and dust.

The load is also taken into account when choosing a part care product. The higher it is, the more the substance is squeezed out of the contact point. Having solid substances (graphite, molybdenum) in its composition, the lubricant will ensure reliable operation of the system. There are even completely dry means of sliding.

Wheel bearing lubrication

The hub bearing is one of the integral parts running car. When it breaks, a knock occurs during the control of the machine.

The functions assigned to the sliding means of the presented part are as follows:

• reduction of friction of the constituent parts of the hub;
• protection against corrosion, pollution;
• create resistance to temperature increase;
• have sealing properties.

Not right choice and the operation of wheel bearing lubrication will cause equipment breakdown.

Lubrication of rolling bearings

The presented type of means for the operation of bearings is used for various types of equipment. Depending on the type of mechanisms, liquid oils, plastic and solid substances are used.

The lubricant used for this type of elements, in addition to the main factors, can take into account the operating conditions of the unit in conditions increased requirements to its cleanliness, the possibility of using the mechanism in the catering department. It can ensure low noise and environmental friendliness.

To decide which lubricant to use for bearings, it should be noted that the most preferred material for this purpose is liquid oil. This substance has best performance removal of heat, worn particles of the body of the part produced by friction. The oil has good penetrating power.

However, due to the increase in construction costs and the possibility of leakage of the substance, plastic means are more often used. They are more durable than liquid lubricants. This reduces construction costs.

Motor bearings

Lubrication for electric motor bearings keeps them clean and prevents dust, sand or dirt from entering the part.

For each type of engine, the appropriate oil is used. It should be changed periodically.

In low-speed electric motors, brand 30 (L) grease is used. For fast-moving varieties, a substance labeled 20 (#3) is suitable. For medium-speed electric motors, both types of the presented means are suitable.

Any system needs periodic topping up of oil. This should be done every 10 days. Also, high temperature bearing grease needs to be completely replaced every 3 weeks at constant use equipment.

Bicycle bearings

Don't skimp on systems products. The quality of this material directly affects the operation of the equipment.

The frequency of maintenance of bicycle bearings depends on the type of assembly design. Sleeves on closed cartridges are serviced much less frequently than on open ones.

Bulk bicycle bearing grease should be changed at least once a season or twice a year.

A hygroscopic variety of a product with a wide range of temperature fluctuations and good adhesion, of a transparent type, is best suited for this.

Complex calcium, sodium lubricants

Of the heat-resistant agents, complex calcium lubricants are the most common varieties, since they have a relatively low cost.

There are two types of them. The first type is uniol, obtained by thickening petroleum oils with kCa-soap of synthetic fatty acids. The second one is CIATIM-221. It is obtained by thickening polysiloxane liquids with kSa-soap.

The first group includes substances such as "Uniol-ZM", "Uniol-1", "Uniol-2".

VNIINP-207, 214, 219, 220 belong to the second variety of complex calcium lubricants. They contain up to 3% molybdenum disulfide.

Of the sodium thermostatic lubricants, the production of only NK-50 has been preserved. It was created before World War II.

Pigment Lubricants

Pigment substances were among the first to be used in the operation of equipment when high temperatures were reached.

One of the most famous is the blue grease for bearings VNIINP-246 (GOST 18852-73). It looks like a rather soft ointment. Its feature is a large limit of operating temperatures: from -80 to +200 degrees.

Blue bearing grease is used for lightly loaded high-speed rolling parts, in electric motors, gear mechanisms operating in conditions of wide temperature run-off or vacuum.

However, this is an expensive product. There are other, cheaper options for such substances. In the same temperature range, dark purple ointment VNIINP-235 is used. But for a full vacuum, it is not suitable. This product is used in low-speed rolling bearings, aircraft control systems.

Lithium greases

Special greases for bearings are lithium varieties. They have high water repellency.

Lithium bearing grease has one of the widest operating temperature ranges. Therefore, it is known as the most versatile slip agent.

The product is prepared on synthetic materials or their mixtures with mineral oils. Various organic and inorganic substances are used as a thickener.

With an increase in the speed of rotation of parts, the viscosity of the substance decreases.

The most famous lubricants of this type include TsIATIM-201, 202, OKB 122-7. For closed type bearings, TsIATIM-203, VNIINP-242 are used.

Solid lubricants

Under certain conditions, for example, full vacuum, cold, high heat, when even a slight contamination of the bearing components with oil is unacceptable, solid varieties of the sliding agent are used.

The most famous representatives are graphite and molybdenum disulfide.

To determine which grease to use for bearings, you need to familiarize yourself with the properties of these substances.

Solid substances have high anti-friction qualities, which are based on their lamellar structure. The shift of the fraction does not require much effort, which ensures a low index of surface friction.

For these purposes, tungsten disulfide, oxides, boron nitride or fluorine compounds are also used.

Such substances are resistant to abrasion. However, to ensure long-term operation of the film of hard varieties, binders with good adhesion are used. The optimal thickness of such a film should be 5-25 microns.

Of the self-lubricating solids, cermet compositions with molybdenum disulfate are used. Also, such mixtures are made on the basis of polymers. Fluoroplasts are considered the most suitable for these purposes.

conclusions

Having considered existing species sliding base, it should be concluded that a special type of substance is used for each type of equipment. Maintenance of the part is quite easy to carry out at home, armed with all the necessary knowledge about this process.

Bearing grease takes into account all conditions and requirements for the operation of the equipment. A properly selected and correctly operated tool will ensure a long service life of the mechanism, regardless of which system it belongs to.

Low-temperature lubricants maintain composition uniformity - oil viscosity or grease consistency - even at extremely low temperatures.

Kluber Lubrication LLC offers lubricants for winter period. Low-temperature lubricants sold by us have all related documents and certificates. You can familiarize yourself with the goods and make a purchase on the company's web resource or by calling the phones offered in the "Contacts" section.

Why Use Low Temperature Lubricants

The temperature of the working medium affects the specific gravity and its density. For products operated in severe frosts, low viscosity coefficients are characteristic. The ability to set is a defining characteristic for evaluating behavior at low temperatures. For areas with permanent frosty conditions, it is very important to use arctic oils with an appropriate pour point.

The operation of various mechanical units does not stop even in the cold season. Many businesses assume non-stop operation. To function properly under these conditions, the lubricant must be of the right specification, maintaining the required level of fluidity and viscosity (for oils) or consistency (for lubrication). Therefore, low-temperature oil differs in its properties from conventional oils, whose viscosity increases significantly when the components crystallize.

Properties of low temperature lubricants

The main characteristics of such lubricants include:

• the presence of special additives that inhibit thickening at sub-zero temperatures;
• low content of paraffinic hydrocarbons;
• the formation of a tear-resistant oil film that can withstand significant loads;
• high viscosity index.

Of course, they also have all performance characteristics greases:

• excellent stability - mechanical, colloidal and antioxidant;
• extreme pressure and conservation properties;
• thermal and water resistance;
• antiwear properties;
• maintaining the uniformity of the composition (oil viscosity or grease consistency is maintained to extremely low temperatures).

Low-temperature oils in the composition contain thickened polymer additives. Pour point, binding characteristics of such substances and density change under the influence of operating temperature and shear rate. Standards that establish their specific density and pour point, in regulations and GOSTs are absent. The oil pour point should be 15...20 °C below the lowest operating temperature of the unit or part.

Application

Low temperature lubricants designed specifically for lubrication technical devices operating in sub-zero temperatures. These oils and greases have excellent protective characteristics for operation in such conditions. The operating temperature can be from -60 to -80 °C. The protective properties of low-temperature lubricants are small. Under mechanical influence, the lubricant can be severely destroyed, and its strength and viscosity/consistency indicators decrease. Therefore, it is not advisable to use these lubricants at increased specific loads. They are used in rolling and sliding bearings, hinges and for rubbing parts in equipment operating at low temperatures at low and medium powers. Often such lubricants are used in instruments, radio engineering devices, in vehicle components, etc. Low-temperature lubricants do not have a chemical effect on metal parts and hardly evaporate.

pour point

The pour point is an indicator to which the lubricant does not lose its properties. The pour point of a lubricant is an indirect coefficient for the loss of its fluid qualities. Due to the fact that there are no other methods for assessing their mobility, the pour point remains the main coefficient of the qualitative composition.

Low temperature greases comply with NLGI GC-LB for bearing (GC) and chassis (LB) lubrication.

Special application includes:

• centralized system in industrial equipment;
• wheel bearings in racing vehicles;
• forestry, construction and mining mobile equipment;
• conveyors and cooling mechanisms;
• wheel bearings and chassis of large vehicles;
• any other equipment, machinery, mechanisms and units that are operated at a wide range of very low temperatures, for example, in the Arctic.

Peculiarities

Low temperature greases are used in cold winter weather due to their softer consistency. Their low temperature properties depend on the chemical composition. The loss of mobility of lubricants occurs due to the crystallization of high-melting paraffin hydrocarbons. The temperature of loss of mobility under standard conditions is called the pour point. This indicator is conditional, but it is used to approximate the low-temperature properties of the operating temperatures of the lubricant. The operating temperature must be 20 °C above the pour point of the grease.

The low-temperature lubricants offered on the site are effective and high-quality means of servicing all friction points in the equipment.

Even the best bearing can only perform to its full potential if it is properly lubricated. The right choice of lubricant, SKF, and lubrication intervals and methods is very important. Realizing this, the specialists of SKF, the world leader in the production of rolling bearings, turned Special attention for bearing lubrication. SKF engineers see grease as a critical component of a bearing assembly, along with bearing components such as the shaft and housing.

SKF's extensive experience in the manufacture of rolling bearings has led to the development of a range of specialty lubricants, the highest quality of which is the result of continuous testing and continuous study of material properties. The stringent standards and test parameters developed at the SKF R&D Center have become the accepted standard for bearing lubricants. The wide range of SKF lubricants is the result of many decades of research and development. Each type of lubricant is specifically designed for use in a specific application.

SKF high-temperature greases allow you to ensure the performance of the assembly at temperatures up to 260 degrees.

LGGB 2
"Green" biodegradable low toxicity bearing grease
Agricultural and forestry machines
Construction and road machines
mining equipment
Equipment for irrigation and water supply
Lawn care machines
Castles, locks and bridges
Joints and rod heads
attractions
Other applications where contamination is undesirable environment

Thickener (soap)
A thickener (soap) is a component that holds the oil and/or additives together, thereby providing the performance properties of the grease. The thickener is made on the basis of soap or other substances. The properties of the lubricant depend on the type of thickener.
Lithium, calcium, sodium, barium or aluminum soaps are used as thickeners. In addition, organic or inorganic substances are used - polyurea, silica gel and bentonite clay.

Note: SKF High Quality High Temperature Grease LGHP 2 is not a conventional polyurea grease. It is a diurea based grease that has positive test results for compatibility with lithium and lithium complex greases.

base oil
The base oil is the oil that is incorporated into the grease and provides lubrication under operating conditions. The most commonly used base oil is mineral oil.
Synthetic oils are used only for very specific operating conditions, such as operation at very low or very high temperatures. The base oil typically makes up more than 70% of the total grease volume.

Viscosity base oil
Base oil viscosity is the shear resistance of fluid layers, usually characterized by kinematic viscosity, which is defined as the time required for a given volume of fluid to flow through a standard orifice at a given temperature. The kinematic viscosity of lubricating oils is usually determined at +40 °C (sometimes at +100 °C) and is measured in 1mm 2 /s=cSt (centistokes).

Additives
Additives are needed to give the grease certain properties (e.g. anti-wear, anti-corrosion, anti-friction and extreme pressure) that prevent damage to bearings during boundary and mixed lubrication

Consistency/penetration
A measure of the "thickness" of a grease.
Grease consistency is classified according to NLGI grades ( National Institute Greases USA). The consistency is determined by the penetration (depth of immersion) of a standard cone into the test grease at +25 °C in five seconds. Penetration is measured on a scale in 0.1 mm increments; softer lubricants have greater penetration. This method is regulated by DIN ISO 2137 standards.

Classification system DIN 51825
Greases for rolling bearings can be classified according to DIN 51825.
Explanations for code KP2G-20 are given in the following tables.

Drop point
The drop point is the temperature at which the grease begins to flow freely forming droplets, measured according to DIN ISO 2176. The drop point is not acceptable operating temperature plastic lubricant.

Mechanical stability
The consistency of rolling bearing grease should not change significantly during operation. The following test is used to evaluate the mechanical stability of a grease depending on operating conditions.

Prolonged penetration
A sample of grease is placed in the penetrometer, followed by 100,000 cone dippings. Then
grease penetration is measured. The change in grease penetration after 60 dives and after 100,000 dives is measured in 10-1 mm.

Roll stability
The rolling consistency of greases must not change during the entire life of the bearings. Evaluation of the stability of the consistency during rolling is carried out by placing a given amount of lubricant in a cylindrical vessel, inside which is placed a roller in contact with the wall of the vessel. The roller cylinder rotates for 2 hours at room temperature. This method is specified in ASTM D 1403. SKF modified this method by changing the test conditions to match the operating conditions and increasing the test time to 72 or 100 hours at 80 or 100°C. After the end of the tests, the grease is cooled to room temperature, then its penetration is evaluated. The change in penetration before and after testing is measured in 10-1 mm.

Testing on the SKF V2F
Grease is tested for mechanical stability as follows:
The test machine consists of a railway box subjected to impact loading from a falling load. Fall frequency - 1 Hz, acceleration - 12-15 g. Tests are carried out at two speeds - 500 and 1000 rpm. Grease flows out of the axle box through the labyrinth seals and is collected in a special tray. If, after 72 hours of testing at 500 rpm, less than 50 grams of grease has leaked out, a further 72 hours of testing at 1000 rpm is carried out. If during the double test (72 hours at 500 rpm and 72 hours at 1000 rpm) no more than 150 g of grease leaked out, the mark “M” is set. If the lubricant passed the first part of the test (72 hours at 500 rpm), but did not pass the second part, the mark “m” is given. If the leak is more than 50 grams after 72 hours at 500 rpm, the rating is “unsatisfactory”.

Corrosion protection
Greases must protect metal surfaces from corrosion. The anti-corrosion properties of greases are determined by the SKF Emcor method, which is regulated by ISO standard 11007. In this method, the lubricant to be tested is mixed with distilled water and placed in the bearing assembly. The bearing rotates according to a cycle alternating stops with rotation at a speed of 80 rpm.
At the end of the test cycle, the degree of corrosion is assessed visually on a scale from 0 (no corrosion) to 5 (very severe corrosion). The test method for advanced conditions involves the use of salt water.
An additional test is the SKF grease washout test with distilled water during a bearing rotation cycle. The procedure in this case is the same as the standard, but the test conditions are more severe, which places higher demands on the anti-corrosion properties of the grease.

Corrosion of copper
Greases must protect copper alloy parts used in bearings from corrosion. The protective properties of greases against copper are evaluated using standard methods according to DIN 51811. The copper strip is immersed in the grease and placed with it in the furnace. Then the strip is cleaned and the condition of its surface is assessed. The test results are evaluated by the corresponding scores.

Water resistance
The water resistance of greases is measured according to DIN 51 807 part 1. The grease to be tested is applied to a glass plate placed in a test tube filled with distilled water. The test tube is placed in a water bath at a given temperature for three hours. The change in the type of lubricant is evaluated visually on a scale from 0 (no change) to 3 (strong change) at a given temperature.

Oil separation
The base oil of lubricating greases tends to separate from the soap base when stored for a long time or when the temperature rises. The degree of oil separation depends on the type of thickener, the type of base oil and the method of manufacture of the grease. When testing, a certain amount of grease is placed in a special vessel with a conical bottom with holes, under a pressure of 100 g. The vessel is placed in a thermostat with a temperature of +40°C for one week. The amount of oil separated is then referred to as a % of the original grease weight. The oil separation test is regulated by DIN 51 817.

Lubricity
The SKF R2F test machine evaluates the high temperature performance and lubricity of greases by simulating the operating conditions of large bearings. The tests are carried out under two different conditions: test A - at room temperature, test B - at 120°C. A positive test result A means that the grease provides lubrication for large bearings under normal temperature and low vibration. A positive test result B at 120°C means that the grease provides lubrication for large bearings at elevated temperatures.

Resource of greases for rolling bearings
The SKF ROF Grease Testing Machine allows you to determine the service life and upper temperature limit of greases. Ten deep groove ball bearings are mounted in five housings and filled with grease. Tests are carried out at a given speed and temperature. The bearings are loaded with a combined (radial and axial) load and rotate until they fail. Based on the durability data for each bearing, a Weibull distribution is plotted and the service life of the lubricant at a given temperature is calculated. The test results are used in determining the relubrication intervals for bearings under specified operating conditions.

Extreme pressure properties

Welding load on 4 ball machine characterizes extreme pressure (EP - Extreme Pressure) properties of grease. This test method is regulated by DIN 5151 350/4. Three steel balls are placed in a cup and lubricated with the lubricant under study, and the fourth is placed on top; this ball rotates relative to three balls at a given speed. The load is increased in increments until the rotating ball is welded to the three stationary balls. This test determines the pressure characterizing the anti-seize properties of the grease. Greases are classified as EP for welding loads above 2600 N.

Wear test on 4 ball machine
This test is carried out on the same equipment as the previous one. A load of 1400 N is applied to the fourth ball for 1 minute. Then the wear of the lower balls is measured. The standard test assumes a load of 400 N. However, SKF decided to increase the load to 1400 N in order to bring the test conditions closer to the actual operating conditions of bearing arrangements.

False brinelling
The anti-fretting properties of greases are of great importance to ensure effective work bearing units. SKF evaluates these properties using the FAFNIR test, standardized as ASTM D4170. Two ball thrust bearings are loaded and vibrated. Each bearing is then weighed to measure wear. A grease is considered anti-fretting if the measured wear is less than 7 mg.

Lubricant - an integral part of the bearing assembly. Altered properties of the oil or hydraulic fluid can lead to equipment failure, so it is important to monitor their suitability. Measurement methods are divided into two groups: absolute(analytical) and relative.

Absolute

Analytical methods are based on the direct measurement of various parameters.

IN Lately began to appear and be widely used meters viscosity. They are a good alternative to costly and time-consuming laboratory tests. Although it does not issue a detailed status report, chemical composition and changing each physical parameter, as a rule, to control the condition of the oil, lubricant or hydraulic fluids, it is enough to know how much the viscosity has changed. The measurement is carried out using a special rotor, by rotation of which the viscosity coefficient is determined. The rotating elements can be replaced depending on the type of oil or to extend the measuring range.

relative

relative measurement methods are based on the comparison of parameter values ​​for new and already used oil.

Some rules for interpreting instrument readings:

• Pollution water and antifreeze lead to the unsuitability of the oil, as evidenced by the movement of the segments in the red area;
• metal particles also lead to the unsuitability of the oil, while the segments on the device screen move in jumps. This is due to the fact that metal particles settle on the surface of the instrument's sensor;
• Presence in oil fuel it is difficult to determine, because it is masked by the presence of other contaminants. If the oil contains only fuel, then the indicator will be in the red area, but the content water or metal can turn the indicator to green;
• Change viscosity oils will lead to a decrease in the dielectric constant, which will make detection difficult;
• Change acidity usually reduces the dielectric constant.

Also, this device is sensitive to humidity, increased temperature And dust that enters the oil when the measured quantity is transferred from the machine to the instrument. The device is not applicable for non-flammable liquids (water-oil solutions).

Packing of greases