What steel are bearings made from?

Bearing steel ШХ15

The development of metallurgy has led to the emergence of steels with special performance characteristics. They are used in the manufacture of certain products that must have special qualities. An example is bearing steel ShKh15, which can withstand high temperatures well. The GOST standard for ShH15 determines the use of certain standards for marking.

Carbon steel ШХ15

Basic properties of steel

In industry, ball bearing steel ШХ 15 is widely used. This is due to the special performance characteristics that allow the use of metal in the creation of bearings and blades. The name steel comes from the fact that almost all bearings are made using this material.

The characteristics of steel ШХ15 are as follows:

1. Increased surface hardness. The bearings and cutting edge of the blade are subject to wear during operation. To ensure that the surface of the product does not react to mechanical stress, the hardness index increases significantly.
2. Wear resistance determines that the surface does not react to friction and other impacts. Metal ШХ9 and ШХ15 are characterized by high wear resistance, so the created products can last for a long period.
3. Corrosion resistance can also be called an attractive quality of the metal in question. Rust that appears on the surface reduces the service life of the product. ShKh15 steel does not belong to stainless steel. Therefore, one should not count on high resistance to high humidity and chemically aggressive environments.
4. Resistance to crushing. Point exposure to high loads can lead to the formation of a dent, but the metal in question is characterized by high resistance to such effects.
5. Plasticity and viscosity are also taken into account when creating various products.
6. The structure lends itself perfectly to heat treatment. As a rule, hardening is carried out after giving the required shape and size. In addition to hardening, annealing and forging are performed, which can also improve the structure of the material.
7. The tendency to temper brittleness determines that structural defects may appear after hardening. They can increase the fragility of the resulting product.
8. Poor weldability. They were able to increase the hardness by increasing the carbon concentration. However, this chemical element significantly complicates the welding process. As a rule, to improve the quality of the weld, the workpiece is heated.

Properties of bearing steel ШХ 15

Steel grade ShKh15, which is deciphered in accordance with established GOST standards, lends itself well to various types of processing and is resistant to crushing. In addition, the surface is characterized by high hardness. The temperature of the critical points is quite high; it is taken into account when carrying out heat treatment.

Download GOST 801-78

Decoding steel

• Ш - ball bearing steel;
• X - the presence of the alloying element chromium in a volume of no more than 1.5%.

Chemical composition and structure

The steel grade in question, ShKh15, has an unusual composition, which determines its special performance characteristics. The grade belongs to low-alloy chromium steels. This determines that the composition contains a large number of special additives, which impart strength, durability and corrosion resistance. The composition includes the following elements:

1. A high concentration of carbon determines increased hardness of the structure. The carbon concentration indicator is 0.95-1%.
2. Manganese is included in the composition of almost any steel. In the case under consideration, the concentration is 0.2-0.4%.
3. Silicon increases the strength and other characteristics of the material. SHH 15 has an indicator in the range from 0.17-0.37%.
4. In most cases, corrosion resistance is achieved by adding large amounts of chromium. ShKh 15 is characterized by low resistance to aggressive chemicals and moisture, since the composition contains only 1.35-1.65% chromium.

Microstructure of Shx15 after quenching in oil

A small amount of chromium determines that it does not form its own carbides, remains in solid solution and can be part of cementite. The structure is characterized by homogeneity with small carbides. It is this property that leads to increased wear resistance.

Processing Features

Today, heat treatment is carried out to increase the basic qualities of the metal quite often. Among the features we note:

1. ShKh15 is hardened quite often. It allows you to significantly increase the hardness of the surface layer. It is worth considering that after hardening it is quite difficult to sharpen the cutting edge. Hardened steel ShKh 15 is difficult to process by cutting. That is why hardening is carried out after giving the workpiece the required shape and size. Heat treatment modes largely depend on the temperature of critical points. It is worth considering that cooling in water leads to the formation of structural and surface deformations. Cooling in the open air is carried out only in case of large product sizes.
2. Annealing of ShKh15 steel is carried out at a temperature of about 800 degrees Celsius. This treatment eliminates internal stresses that cause cracks and other defects. As a rule, annealing is carried out after hardening the product. To carry out such a process, various equipment can be used.
3. The workpiece can also be forged, for which it is heated to 1150 degrees Celsius. Cooling is carried out outdoors or in a pit. When forging, the structure of the material becomes more dense and resistant to various impacts.

When considering the main qualities, the tendency to temper brittleness is taken into account, as well as the ability to carry out cutting processing. A variety of equipment can be used for heat treatment. The high melting point means that improvement is extremely rare at home.

Areas of application

The use of ShKh15 steel is largely due to the high hardness and strength of the structure, as well as insignificant corrosion resistance and wear resistance. The alloy is used to obtain:

1. Balls used in the manufacture of bearings. During the operation of bearings, this element is subjected to strong mechanical stress. Therefore, special attention is paid to their production; the product is often hardened.
2. Rollers with a diameter of up to 23 mm. Roller bearings that are designed for heavy loads are also available for sale.
3. Plungers.
4. Discharge valves. They are also subject to significant impacts at the time of operation.
5. Push rollers.

Steel ball for bearing ШХ-15

The fact that the ShKh 15 alloy is called a bearing alloy determines its use in the creation of such products. They can withstand long-term use, withstand friction and other mechanical stress, and high temperature.

Knives made of steel ШХ15

ShKh15 steel is characterized by versatility in use. It is used to produce a wide variety of knives, like the ShKh16 alloy. Today the brand is considered one of the most popular, which is due to its low cost. The ShKh15 knife is characterized by the following qualities:

1. The blade lasts for a long period. Good wear resistance means that the cutting edge does not need to be sharpened frequently.
2. The cutting edge holds its edge for a long time.
3. The surface cannot be sharpened. Therefore, after its loss, it is quite difficult to restore it.
4. The cutting edge is not exposed to moisture and various chemical elements. Over a long period, no rust or oxidation appears on the surface.
5. The resulting blade is not brittle, the surface is hard. That is why the scope of application of the knife is expanding significantly.

ShKh15 steel is used to create products that are used under the most severe conditions. However, the material is not universal, which is due to its relatively low corrosion resistance.

Source: https://stankiexpert.ru/spravochnik/materialovedenie/stal-shkh-15.html

Purpose of bearings

The bearing is a complex assembly unit, which consists of several main elements: outer and inner rings, rolling elements, a cage and a special rolling groove. This design allows for rotational directional movement while ensuring a minimum level of friction.

Actually, due to these features, the main purpose of bearings is to fix a rotating part in a mechanism, allowing it to perform both rotation and rolling, and in some cases, linear movement with the minimum possible surface friction coefficient.

The final purpose of bearings depends on several third-party factors. Firstly, there are different types of bearings and their classifications , for example, according to the way they carry loads.

the technical characteristics of the bearings largely depend on this . Secondly, there are various applications of bearings , each of which has its own personal characteristics.

For example, in mechanical engineering, these products need to withstand enormous loads, but in children's toys, products are required that are less resistant to high mechanical stress.

However, regardless of the area of ​​application of bearings one or another type of bearing , each of them requires special lubrication for stable operation. In some cases, various synthetic substances are used for such purposes.

Sometimes organic bearing lubricants ; in addition, there are also mineral lubricants. In principle, whatever the type of lubricating fluid, its main task is to prevent the rolling elements from coming into contact with the surface.

To achieve the best performance of the product, its lubricant is selected according to the characteristics for the purpose of the bearings .

Types of bearings and their classification

Modern hardware plants produce different types of bearings for different industrial needs and their classification is divided into three main types:

Bearing classification	Character of the perceived load:
Radial bearings	Radial
Thrust bearings	Axial
Angular contact bearings	Both radial and axial

In the first case, radial load refers to the load that is perpendicular to the geometric axis of the shaft. In the second case, the axial load is the load that acts on the bearing axis in only one direction. In the third case, the bearings will be able to simultaneously absorb both types of loads, but with a predominant axial load.

If we consider the types of bearings , then there will be only 2 main varieties:

• Rolling bearings
• Plain bearings

Despite the fact that in general the principle of operation of a bearing implies the free rotation of a trunnion inside it, its moving elements can be different. For example, a plain bearing has only a ring as a rotating element.

In this case, the ring can be solid, and such a bearing is called one-piece. The principle of its operation is that the shaft is placed in the inner ring, which rotates in relation to the outer housing. There is also a split bearing, in which the ring consists of two separate parts.

In this case, the shaft is fixed in one of them, and only after that the second one is installed.

At the same time, it is generally accepted that split types of bearings, due to their design features, are most optimal for use.

Despite the fact that the technical characteristics of split-type sliding bearings practically do not differ from the characteristics of one-piece bearings, the greatest ease of their installation and dismantling is one of the significant advantages.

Due to the fact that the inner ring of sliding bearings is convex, and the outer ring, on the contrary, is concave, when exposed to multiple static loads, this type of structure makes it easy to move and turn at low speeds.

Technical characteristics of plain bearings
Advantages	Flaws
Low noise level during operation	Have low efficiency
Operation at high temperatures	Break down due to poor quality lubricant
Resistance to mechanical loads	Requires monitoring of working conditions

Unlike the previous version, rolling bearings between the inner and outer housings have auxiliary elements in the form of balls, cylinders or other round-shaped bodies that can roll freely between these two housings.

It is important to note that the rolling elements in such bearings can be installed at an equidistant distance from each other. This placement allows for the best efficiency. For this purpose, the rolling elements are placed in a special separator ring. There are types of bearings where there is no cage.

In this case, the maximum possible number of rolling elements is tightly driven inside.

In this case, the rolling bodies can be arranged in either one or two rows. As a rule, double-row bearings can withstand slightly larger loads, since all the impact is absorbed by the rolling elements.

The choice of body shape is determined based on the purpose of the bearings and in what specific mechanism they will be used. This is important because each such form has its own degree of resistance to various types of mechanical stress.

In addition, the direct size of the bearing , and this is very important, since there are both small and large mechanisms.

Technical characteristics of rolling bearings
Advantages	Flaws
Virtually silent operation	Stop working in aquatic environments
Work even at high temperatures	Their production is quite labor-intensive
Resistance to mechanical stress	High price and less reliability

About the application area of ​​bearings

Different industrial sectors have their own specialized bearing applications .

If we consider the main areas where bearings are used , namely mechanical engineering, aircraft manufacturing, carriage building and machine tool building, then we can see that for the most part bearings are used as part of various devices on shafts with small diameters.

At the same time, for operation under small or medium loads, ball bearings are usually used. In cases where work with heavy loads is necessary, then roller bearings are installed. And if not only resistance to high loads is required, but also small dimensions, then cylindrical roller bearings come to the rescue.

In addition, bearings are often used as components in various areas of domestic use. For example, in children's toys and accessories, in household appliances, in quadcopters and medical devices, for example, dental chairs and tomographs.

They are also found in motorboats, speedboats, bicycles and skateboards. They are often used in room furniture, as well as in sliding doors.

In general, if we consider all areas of application of bearings , we will notice that such products cover many different areas of life, while bearings significantly simplify them.

Bearing markings

One of the final stages of bearing production is the application of special identification marks to them, in other words, markings. Actually, the bearing marking , depending on the country of origin, may vary.

In Russia, it is customary to apply a designation consisting of capital letters and numbers, divided into three separate blocks. The main one is central, consists of 6 digits. To the left of it, another number is indicated through a hyphen. A special alphanumeric designation is added to the right of it.

As an example of how bearing markings are deciphered , we will look at model 6-180306US17Sh.

What do bearing markings mean?

6	18		3	06	U	C17	Sh
Accuracy class	Subspecies	Product type	Series by outer diameter	Inner diameter	Roughness degree	Lubricant type	Noise level
Accuracy class
Name	Designation
Normal	Not marked
Ultrahigh	2
Particularly high	4
High	5
Elevated	6
Reduced	7 or 8
Product type
Name	Designation
Radial
Spherical	1
Radial with short rollers	2
Radial spherical	3
Needle	4
Radial with twisted rollers	5
Angular contact	6
Conical	7
Persistent	8
Thrust-radial	9
Series by outer diameter
Name	Designation
Extra-light	1
Lightweight	2
Average	3
Heavy	4
Light wide	5
Medium wide	6

If we talk about the internal diameter of these products, then it is necessary to identify one very important feature. If the inner diameter of the bearing is more than 20 mm, then the numbers contained in the bearing markings, namely 06 in our case, need to be multiplied by 5. Then we get the final size - 30 millimeters. If the diameter is less than 20 mm, then to determine its value you can use the following table:

Designation in marking	Inner diameter size in mm.
00	10
01	12
02	15
03	17

The right side of the bearing markings begins with a letter designation. In this case, we have the letter U, which indicates the tolerances of the material according to the degree of its roughness. Next is the type of bearing lubricant used by the factory.

In our case, this is C17 lubricant, that is, a multi-purpose lubricant GOST 21150-87 brand Litol-24, which can withstand temperatures in the range from -40°C to +120°. Finally, the noise class of the product is indicated. By default, it is designated by the letter “Ш”. Depending on its requirements, on an increasing scale, this designation is numbered 1, 2, 3 and so on.

In addition, in some cases, bearing markings may also contain other specialized designations from the factory.

Source: https://s-agroservis.ru/inform/company-news/prednaznachenye_podshipnicov/

What steel are bearings made from?

The characteristics of the use of ShKh15 steel, as well as the process of its production, led to the fact that it began to be classified as a structural steel.

Steel structure

The most important requirement for this type of steel is high hardness. In order to achieve this indicator, a large amount of carbon is used as an alloying element, and a certain amount of chromium is also added.

At the time of delivery of this steel, its structure is a ferrite-carbide mixture. Most often, when this type is supplied, it is written that it is annealed to granular perlite. It is also important to note that the characteristics of the use of ShKh15 steel include high ductility, which must be observed, since raw materials of this grade are often used for the production of various plastic structures.

The steel hardening temperature at which it undergoes heat treatment is 830-840 degrees Celsius. The release of raw materials is carried out at a temperature of 150 to 160 degrees, and the time required to complete the operation is 1-2 hours.

Carbide phase

Further characteristics of the use of ShKh15 steel largely depend on the carbide phase and its successful completion. If we examine its progress under a microscope, we can observe that upon successful completion, the force required to destroy the matrix is ​​140 kN.

In order to achieve such an indicator, the ball, which is the main element of the structure, must have a homogeneous matrix, as well as sufficiently homogeneous carbides. They must be identical both in size and in their distribution in the matrix.

If something goes wrong during processing, the force required to destroy the structure can drop to 68 kN. If this happens, it means that the structure of the ball is heterogeneous. The carbides in this case may be unevenly distributed and/or of unequal size.

This indicator is very significant for steel.

Carbide phase defects

Since the characteristics of the use of ShKh15 steel largely depend on the flow of the carbide phase, it is important to know what defects this process may have:

• One of the first defects is carbide banding. It occurs due to the fact that there is heterogeneity in the structure of the steel after hardening. In those areas where a large amount of carbides is present, a martensite-troostite structure appears, and in those areas where the amount of this substance is small, acicular martensite appears.
• Another defect that can occur is carbide segregation. In bearing type steel, large inclusions of carbides are often found, which are located along the rolling direction - this is called carbide segregation. The defect of this phenomenon is that these elements are characterized by high strength, but also high fragility. Most often, such elements are destroyed when steel reaches the working surface, which creates a source of destruction. A pronounced defect of this type greatly increases the wear of ball bearing steel.

Steel bearings

Due to the application characteristics of ShKh15 steel, it is often used for the production of balls, rollers and bearing rings.

It is worth noting that during operation of these parts they are constantly exposed to high alternating stresses. It is also important to understand that the roller or ball, as well as the track of rings, experience a high load at a single moment in time, which is distributed over a very small area of ​​the plane. Because of this, alternating stresses of the order of 3-5 MN/m2 (300-500 kgf/cm2) alternately arise in such areas.

It is because of such loads that the hardening temperature of the steel is very high in order to impart high strength to the material. It is also important to note that such high loads do not pass without leaving a trace; they leave a slight deformation of the bearing elements.

Because of this, fatigue cracks form on the bearing.

The appearance of these defects leads to the fact that when passing through this section, an impact occurs, due to which the deformation only intensifies, and ultimately the bearing completely fails.

Bearing steel: characteristics

This grade of steel is used for the production of balls with a diameter of up to 150 mm, rollers with a diameter of up to 23 mm, as well as for the production of bearing rings with a wall thickness of 14 mm. This steel can also be used for the manufacture of plunger bushings, injection valves, and other parts for which the main requirement is high hardness, high wear resistance, and contact strength.

Bearing steel of this grade also has a number of certain characteristics, such as: a tendency to temper brittleness or flake sensitivity. The short-term strength limits of this material are in the range from 590 to 750 MPa.

The proportionality limit for this material is 370-410 MPa. The relative elongation of the material at break is 20%. Steel grade ШХ15 has a relative narrowing of 45%.

In addition, there is also an impact strength characteristic, the value of which is 440 kJ/m2.

Properties of steel ШХ15

If we talk about the properties of this brand, then you need to pay attention to its chemical composition, which largely affects the formation of these properties. ShKh15 steel contains the following chemical elements:

• C - 0.95 -1.0;
• Si - 0.17-0.37;
• Mn - 0.2-0.4;
• Cr - 1.35-1.65.

This brand is also characterized by another parameter - the critical temperature point. For steel ШХ15 this figure is in the range from 735 to 765 degrees Celsius.

In order to achieve the required strength, this type of alloy is subjected to intense heating, the temperature of which exceeds the eutectoid transformation. It provides the required concentration of elements such as C and Cr in the steel composition in solid form, and also creates a fine, homogeneous grain structure.

The interpretation of steel ШХ15, which is obtained as a result of all these operations, is as follows: the letter Ш indicates that the material belongs to the group of bearing steels, and the letter X indicates that the raw material contains a material such as chromium, which is one of the alloyed elements.

ShKh15 steel is a carbon and low-alloy steel, which in the manufacture of knives has acquired the name “carbon”. This material has been used for approximately 100 years. The main area of ​​application of this material is bearing, wear-resistant and cutting parts or elements.

It is also worth noting that this group of steel is classic for making knives abroad. A knife made from ShKh15 will have enormous strength, as well as significant sharpness. Such products are most often used for any cutting tools, but ordinary kitchen knives can also be made from it.

  Electroplasma polishing of stainless steel

Features of use

The interpretation of steel ШХ15 speaks for itself, but it is worth adding that 15 is an indicator of the amount of chromium in the material, which is contained there in the amount of 1.5%.

When operating products made from this steel in a metastable environment with high loads, geometric changes in the dimensions of the part are quite possible.

After observing hardened samples and their changes in size, as well as after conducting x-ray studies, people found that in order to stabilize a substance such as martensite, it is necessary to harden the raw material for 2-4 hours at a temperature of 150 degrees Celsius.

If it is necessary to stabilize martensite for further operation of the substance at elevated temperature conditions, then the tempering process must take place at a temperature threshold that will exceed the operating temperature by 50-100 degrees Celsius.

It can be noted that the main reason why, after quenching and tempering, steel changes its geometric parameters is the influence of retained austenite. To give a clear example, we can imagine the following statement: 1% of authensite, when transformed into martensite, will change the size of the part by 1•10-4. For a clearer definition, this means that the size change will occur by 10 microns for every 100 mm of size.

Source: https://steelfactoryrus.com/iz-kakoy-stali-delayut-podshipniki/

Bearing shell

Bearing housing is a part or assembly unit designed to fix one or a group of bearings and install them in a machine. Their classification includes the following types:

• according to the principle of fastening - on feet, flanged, with special types of fastenings, for example, for linear movement (T), for rotation;
• by the number of bearings per one, two, group;
• by material - cast iron, steel, aluminum, stainless steel, plastic;
• by type of workpiece - welded, cast, stamped, forged, from a solid billet;
• detachable and non-detachable;
• standardized, purchased serial, designed for a specific machine.

For large-scale production, the most rational and cheapest method is to obtain housing blanks for bearings by casting. Gray cast iron casting is more often used, providing rigidity and strength at low cost.

For special requirements, steel and aluminum castings are used. However, casting requires costs for molds and foundry equipment. In single or small-scale production, such costs are not recouped. In this case, welded blanks are used. The material is usually low carbon steel St3 or steel 20.

In the food industry, when there is a possibility of contact with the product, the need for sanitary treatment, and washing, stainless steel is used, for example 12Х18Н10Т. Bearing supports made of plastic are mainly made by injection molding. Housings made of durable chemical-resistant plastic and stainless steel are used in chemical equipment in addition to the food industry.

For tension supports, gray cast iron is often used as a material, forming a good friction pair with steel guides.

From solid rolled products, for example, a circle of support, they are made in small sizes.

Regardless of the type of workpiece, the housings are subjected to rough and finishing machining. Usually, the support feet are processed first by milling the plane or turning the flange. Using the supporting surfaces as a base, bore a hole for the bearing.

If necessary, the ends for the covers are machined, grooves are made for spring thrust rings, and surfaces for sealing devices. Mounting holes are drilled on the flanges, feet, and holes for the covers. Threaded holes for grease fittings, channels and lubricant supply holes are made.

Often, to allow for adjustment, grooves, rather than holes, are made on the paws.

Bores for bearings are usually made cylindrical for passage.

In some cases, sharpening is performed for axial fixation of bearings.

In housings with a spherical top ring, the seating surface is bored along the sphere.

In supports for two bearings, borings are made at the ends of the housing. To reduce the amount of precision machining in the central part of the housing, the hole has a diameter larger than that of the bearing. When casting, the central rod of the mold is made at the ends with diameters suitable for boring, and in the center with a diameter larger than that of the bearing. Welded housings for two bearings are usually made from a pipe with a diameter larger than that of the bearing, so that bosses with holes for a boring allowance are welded at the ends.

In some cases, when implementing the stretching scheme, the diameter of the pipe of the welded body is selected according to the size of the thrust shoulder of the bearing, making borings at the ends.

The values ​​of the cleanliness of the support boring for the outer ring with a diameter of up to 80 mm are Ra 0.81.6, and in the diameter range of 80500 mm Ra 1.6.

When installing a bearing into a housing, a rotational load usually acts on the inner ring. In this case, the housing bore size is made to the tolerance:

• H7 in most cases;
• G7 at elevated shaft temperatures;
• JS6 at higher speeds.

Split housings, consisting of a base and a cover, make it easier to install bearings, adjust the gap, and perform repairs. The base is secured with a lid using studs and nuts. However, such housings are more difficult to manufacture and more expensive, which limits their use.

Standardized and purchased enclosures

There are standardized bearing housings in accordance with GOST, the use of which allows you to speed up the design process, avoid errors, and reduce production costs. Cast housings type ShM in accordance with GOST 13218.1-80 are used for bearing diameters of 47-150 mm. These are wide bodies on feet with a through-type boring. They are non-detachable. For axial fixation of the bearings, places are provided for fastening the covers at the ends.

The ShM series for diameters of 160400 mm is determined by GOST 13218.2-80.

State standard 13218.3-80 defines the dimensions and technical requirements of a one-piece narrow body of the UM type on feet, with a bore through for an outer ring diameter of 80150 mm. For the size range of 160400 mm, the design parameters of the UM series are determined by GOST 13218.4-80.

Standardized wide cast large supports ШБ with fastening with paws and through boring for rolling bearings are determined by GOST 13218.5-80 for borings of 80150 mm and GOST 13218.6-80 for diameters of 160400 mm.

The dimensions and requirements for narrow large bodies with UB feet are specified by GOST 13218.7-80 for diameters of 80150 mm and GOST 13218.8-80 for bores of 160400 mm.

The design and dimensions of detachable wide housings РШ on feet with boring through for rolling bearings with outer diameters of 110400 mm are determined by GOST 13218.9-80, and for a series of split narrow RU - GOST 13218.10-80.

Standardized bearing housings are usually used in pairs to secure a long shaft using a floating bearing arrangement. The choice of support is made according to the diameter, width of the rolling bearing, and load level. The ends of the supports are closed with blind covers or with shaft seals.

The bearing is placed in the floating support with gaps on the sides, and in the fixing support you can install spacer rings or make covers with sharpenings of the appropriate size.

If it is difficult to ensure strict alignment, use spherical self-aligning ball or roller bearings that allow slight misalignment of the shaft axis.

For such supports, standardized end caps with reinforced cuff seals are suitable:

• low GOST 13219.5-81 for diameters 47100 mm;
• low GOST 13219.6-81 for diameters 110400 mm;
• medium GOST 13219.7-81 for diameters 47100 mm;
• medium GOST 13219.8-81 for diameters 110400 mm;
• high GOST 13219.9-81 for diameters 47100 mm;
• high GOST 13219.10-81 for diameters 110400 mm.

Standard end caps with labyrinth seal grooves are also used: low, medium, high for diameters of 47400 mm in accordance with GOST 13219.11-81 GOST 13219.16-81.

In some cases, you can use ready-made commercial bearing housings. They are produced by a number of manufacturers. SKF offers a particularly large selection.

Stationary split bearings of the SNL series, replacing the outdated SNH, are designed for the installation of bearings on an adapter sleeve and allow a variety of sealing and lubrication options. The SNL series is characterized by improved strength and increased heat dissipation. Installation into the equipment is carried out on the feet with two bolts, and on standard sizes 511609 with the designation FSNL with four bolts. The positions for the fixing pins are marked at the base.

Retaining pin in bearing housing

The size range is designed for shafts with a diameter of 20160 mm. The support can be used either floating or fixed by adding two spacer rings of the FRB brand indicating the width and outer diameter in mm, which are ordered together with the support. The support base and cover are not interchangeable and are used as one set. It is possible to equip with four types of seals for a temperature range of -40+100 degrees Celsius:

• cuffs with two edges TSNG, allowing peripheral speeds of up to eight m/s;
• V-type TSNA seals for peripheral speed 7 m/s;
• improved taconite TSNND seals up to 12 m/s;
• TSNS labyrinth seals at any peripheral speed and temperatures of -50200 degrees.

Supports of series 5.6 are used for bearings with a tapered hole on the adapter sleeve, and series 2.3 for bearings with a cylindrical hole.

If necessary, an ASNH brand blind end cap can be used. The housings have holes for oil nipples. Body material is gray cast iron, boring tolerance is G7, axial distance to the reference plane is made with js11 accuracy.

Designation of the SNL housing for a 40 mm shaft with bearings on an adapter sleeve, two SNL 509 TL seals, where:

• SNL 509 case;
• TSN 509 L - seals.

If necessary, the designation of the end cover for it is ASNH 509.

Split stationary housings on SONL type feet with bath oil lubrication are designed for spherical roller bearings type 222 or toroidal type C22 and are made of gray or high-strength cast iron.

Centralized lubricant supply system to the bearing housing

Large-sized split housings stationary SDG for spherical bearings on an adapter sleeve for shafts 125530 mm, with a withdrawal sleeve 135600 mm, with a cylindrical hole 140710 mm.

Stationary one-piece housings on SBD feet with bearings on adapter bushings are suitable for shafts 90400 mm, bearings with a cylindrical hole 100420 mm.

One-piece housings on feet TVN for 2075 mm shafts, TN for self-aligning ball bearings 2060 mm, flanged triangular housings with three holes I-1200 for the same ball bearings, flanged one-piece triangular or square housings 7225 for shafts 20100 mm are also supplied.

Original supports

It is not always possible to select standardized or purchased supports.
Often there is a need for non-standard supports. The bearing housing drawing is made based on the design of the machine. In this case, it is advisable to use three-dimensional design programs. During the design process, you can use the reference materials contained in the second volume of the Mechanical Designer's Handbook in three volumes by Anuriev.

Source: http://themechanic.ru/bearings/b-articles/korpus-podshypnika

Bearing steel: types, features and characteristics

Bearings sometimes carry extremely high loads, so high demands are placed on their reliability, strength and durability. Steels for the manufacture of bearings are compounds of the highest quality, characterized by maximum wear resistance and excellent coping with large contact loads.

Types of steel

All mixtures are usually classified according to two parameters:

- for parts used at high temperatures and exposed to aggressive chemicals. The category includes heat-resistant and corrosion-resistant metals;

- for parts operating under standard conditions. These include compositions containing chromium and manganese, chromium mixtures with the addition of molybdenum and silicon.

Among the compositions of the first group, brands 95Х18-Ш, 11Х18М-ШД, etc. are popular. Such brands are used in the manufacture of instrument rolling bearings operating in aggressive environments.

— the designation “Ш” means that the parts belong to a particularly high class and are produced using the standard electroslag remelting method,

— designation “ШД” - using vacuum-arc remelting. This steel is used in precision bearings with an accuracy class higher than P4, that is, P2, P3, P4. Accuracy class P2 is considered ultra-high and is very rare.

In the second category, the recognized leaders are the models ShKh15, ShKh15SG, ShKh20SG.

Quality of bearing compounds

The specificity of their application is such that the components of rolling parts (roller, ball, ring elements) are constantly under the influence of high alternating voltage. Because of this, their surface is subject to tension at the edges and compression in the center. The magnitude of the load can reach 500 kg/cm2, which significantly deforms the part, leading over time to the formation of fatigue cracks.

Ball bearing products are subject to mechanical destruction of the metal (abrasion). Friction forces lead to small elements starting to break off from structures, and their abrasive wear is significantly accelerated.

The listed factors indicate that composite compositions for bearings must meet:

— the highest possible strength qualities;

— resistance to mechanical wear;

- significant elasticity;

- minimal fragility, combined with high resistance to metal fatigue.

Bearing compounds should not have non-metallic inclusions. The requirement is due to their functional specificity, since the components of the parts are in contact with each other by working surfaces. If the technology is not followed, they quickly become unusable.

Components of mixtures

All elements are indicated as percentages:

— ШХ20СГ. : silicon – 0.55-0.85; carbon – 0.9-1; manganese, chromium - 1.4-1.7, sulfur - 0.02, nickel - 0.03, phosphorus -0.25.

— ШХ15. Silicon – 0.17-0.37; carbon –0.95-1.05; chromium – 1.3-1.65; manganese – 0.2-0.4; other elements - similar to the previous paragraphs.

— 11Х18М-ШД. Silicon – 0.53-0.93; carbon – 1.1-1.2; chrome – 16.5-18; manganese – 0.5-1; sulfur – 0.15; copper and nickel – 0.3; phosphorus – 0.025.

Compositions for bearing structures contain carbon impurities. Thanks to carbon, it is possible to ensure resistance to abrasion and increase strength after heat treatment of the product itself.

Manganese and chromium added to the composition (composite material) increase resistance to abrasion and at the same time impart hardness to the product. However, both of these components are deoxidizers and can reduce the viscosity of the metal composition, so their amount must remain strictly within certain limits.

The key element in the bearing alloy is chromium. Carbides of this substance increase the wear resistance of the metal and its hardness, provide the desired fine-grained structure, prevent it from overheating, and increase the resistance of martensite to tempering.

Harmful impurities

Other impurities negatively affect the quality of the composition (composite material), so their content is strictly limited:

- nickel. A large amount of the substance significantly reduces the hardness of the alloy;

- copper. Excess in the mixture increases the risk of deformation and dangerous damage;

- phosphorus. Provokes metal fragility and cracking during hardening;

- lead, tin, arsenic, nitrogen. An amount of this material in a ten-thousandth part of a percent causes coloration of the metal.

The view that sulfur has a positive effect on the bearing mixture, facilitating processing and promoting long service life, is becoming popular abroad. However, domestic metallurgists do not agree with this, since metals with a sulfur admixture of more than 0.15% are subject to fatigue and rapid abrasion.

Source: https://newpodshipnik.ru/podshipnikovaya-stal-vidy-osobennosti-i-harakteristiki

Bearing scrap

The demand for bearings is observed in various industries and at the household level. Even collection points for recycled metals do not ignore this product. Indeed, bearings, depending on the model, differ in the content of various metals and alloys:

Therefore, it is possible to sell bearings for scrap quite profitably, at prices comparable to the cost of non-ferrous metal waste.

Source of quality alloy steel

The value of bearings lying around in the garage since Soviet times is determined by the quality of the metal. A separate category 3B3 is allocated for scrap of integral structures or their parts made of alloy steel.

Bearing scrap accumulated in production

As a rule, the main components of the product are: balls, rings and rollers; made of ball bearing steel, the range of grades of which is quite wide - ShKh15, ShKh15SG, ShKh20SG, ShKh4, ShKh6, ShKh9, etc. The specific type of metal is selected based on performance characteristics. High-carbon steel grades are typical for the following bearings:

1. Operated under standard conditions. The product contains chromium alloyed steel with additions of manganese and molybdenum silicon (grades ShKh4, ShKh15 and ShKh20SG).
2. Operating under extreme load, including aggressive environments or high temperatures. Heat-resistant and also corrosion-resistant metal is used. The steel grades used in such bearings are smelted using electroslag or vacuum-arc remelting technology, for example 95Х18-Ш and 11Х18М-ШД, respectively.

Less commonly, the design may contain steels with low carbon content, since such metal is significantly inferior in hardness.

The steel type of a product can be determined by eye based on its size: for larger units and rolling elements, alloy metal with a high concentration of silicon and manganese is used. Large-sized parts are usually made from ShKh20SG grade. Special steel ШХ4, used inside railway rolling bearings. This brand is distinguished by regulated hardenability.

Alloys of non-ferrous metals based on tin and lead

Babbitt's special anti-friction alloys, whose intricate name is taken from the name of their developer, are intended directly for use inside bearings. The metal is poured or sprayed onto the body of the product liner.

Bearing shell with babbitt surfacing

The basis of this bearing alloy is tin and lead, while other non-ferrous metals are additives: copper, nickel, cadmium, sodium, magnesium and others.

Less valuable as a secondary metal, lead-based babbitts are intensively used for casting bearings in diesel engines and rolling machines, which is due to their higher operating temperature compared to the tin-based antifriction alloy. This is mainly the B16 brand, although there are other varieties, such as BN, BKA or BK2SH.

Bearings of railway rolling stock contain lead-potassium babbitt. On the contrary, the lead-zinc alloy COC6 is used in structures operating at high pressure and temperature, for example, automobile diesel engines. Standard operating conditions, up to 15 MPa, are acceptable for bearings filled with high-tin content Babbitt, an alloy most valuable at recycling sites.

Copper alloys

When considering a metal product as scrap, special attention should be paid to plain bearings. Their main components are: bushings, springs and liners; often made from a copper alloy - cast tin bronze. Alternatively, bearing shaped castings are often made from tin-free aluminum bronze.

https://www.youtube.com/watch?v=_CqdItraHaM

In recent years, non-metallic materials have replaced copper alloy for the manufacture of sliding bushings: fluoroplastic, caprolon. However, despite the ease of installation, they cannot completely replace bronze, since they are much inferior in durability.

Part of the plain bearing housing

An alternative metal material for the manufacture of sliding bushings is brass. This copper alloy has found more universal application in components of this type of product. Brass is used as a replacement for steel in the manufacture of cages for rolling bearings.

Features of delivery of specialized scrap

The situation on the bearing delivery market is ambiguous. Both end-of-life products and new “Chinese samples” are returned as waste. Unliquid stock or long-term storage products are purchased. Products are accepted as a whole, as well as individual units. Naturally, the main factor determining the cost of scrap remains the type of metal. Products made from copper alloys, babbitts, are more expensive than steel bearings.

Source: http://xlom.ru/vidy-metalloloma/lom-podshipnikov/

Bearing steels

Bearing steels are subject to high demands, mainly in terms of hardness, wear resistance and fatigue strength. These requirements are ensured by a combination of optimal chemical composition and heat treatment for the required hardness. For general purpose ball bearing steels (type ШХ15), the hardness after heat treatment is usually 60-64 HRC (quenching + low tempering 150 - 190°C, 1.5-2 hours).

In addition, bearing steels are often subject to requirements for a minimum content of non-metallic inclusions and carbide segregation, which can cause premature failure of the product.

In addition to quenching and tempering, cold treatment at -80°C is used for steels that require dimensional stability.

Most ball bearing steels contain chromium in their structure, which promotes the formation of carbides. This increases the hardness and wear resistance of the balls and rollers. Chromium steel, for example ShKh15, after quenching and low tempering will have low tempered martensite and a small amount of carbides in its structure.

Bearing steel grades

Steels for bearings are divided into general purpose steels (ShKh15, ShKh20SG), steels operating in aggressive environments (95Х18) and steels for bearings operating under dynamic loads (20Х18Н4А, 20Х18Н4ВА, 18ХГТ). The last group of steels is strengthened by carburization to a layer of 0.8 - 3.5 mm. and sometimes is additionally subjected to surface hardening, which improves the fatigue characteristics of the steel.

Marking of steels for bearings

Steels 20Х18Н4А, 20Х18Н4ВА, 18ХГТ, 95Х18 are marked like all structural steels.

In steels of the ШХ group, the letter Ш indicates that it is a ball-bearing steel, and the letter Х followed by numbers indicate the chromium content. For example, ShKh15 steel contains about 1.5% Cr (1.3 - 1.65% Cr according to GOST 801-78). All steels in this group contain approximately 1% carbon. According to the same GOST 801-78, the chemical composition of these steels is as follows

In addition to chromium, the labeling may indicate silicon and manganese - ШХ15СГ, ШХ20СГ (see chemical composition according to GOST).

Bearing steels produced by special smelting methods are additionally designated by a hyphen at the end of the brand name with the following letters:

Ш - electroslag remelting (ШХ15СГ-Ш). There is a designation DS - double remelting

B - out-of-furnace treatment with vacuum

PV - direct recovery

Source: https://HeatTreatment.ru/podshipnikovye-stali.html

Bearing materials and technology for their heat treatment

From steels alloyed with chromium, taking into account the high complex of mechanical properties, special resistance to wear from abrasion, and the relatively low cost, steels of the ShKh group were chosen for the manufacture of bearing parts: for balls and rollers - ShKh6, ShKh9, ShKh12, for rings - ShKh15. A rod or forgings (stampings) made from it were used as the initial blank for making rings.

Before the Great Patriotic War, in the total volume of steel used for the production of bearings, 99.5% was steel type ShKh and only 0.5% - other grades. The main types of heat treatment were hardening and tempering. The outer diameter of the bearings did not exceed 400 mm.

However, already in the early 50s of the 20th century, bearings with an outer diameter of up to 1.42 m with a complicated ring configuration were required, the hardening of which required hot media, hardening devices with rotating rolls, stamps and other devices.

In addition, there was a need to use such a labor-intensive chemical-thermal treatment operation as carburization in a solid carburizer. At this time, about 10% of case-hardened and other steels were already used for the manufacture of bearings.

Three-layer compositions for liners made of steel, porous Cu-Ni alloy and lead alloy have become widespread.

Large-sized bearings were first made from ShKh15 steel, but due to the appearance of soft troostite spots on the surface of the rings after hardening, all rings with a diameter of more than 200 mm are made from ShKh15SG steel.

Bearings subject to wear are made of hard-hardening steel, and bearings subjected, in addition to wear, to significant impact loads are made of case-hardened steel. For cementation, city gas of the following composition is used: 9095% CH4; 13% CO; 1% CO2; 1% 02; the rest is nitrogen.

Simultaneously with the transition to carburization using city gas for parts of large bearings, a carburization process was carried out using a gaseous caburizer in furnaces with a rotating retort (for rings of small dimensions made of steel 20Х2Н4А) and in pusher furnaces of the type Ts-160 and TPSA (for cold-formed rings from steel 18ХГТ).

For rings with a thickness of more than 35 mm and rollers with a diameter of more than 55 mm, steel ШХ20СГ (GOST 801-78), 95X18 and 8Х4В9Ф2 are used. Babbitts BKA and B16 (GOST 1209-78) have been used for railway bearings.

To manufacture the most precise and heavily loaded bearings, steel types ShKh15SG-Sh, 95X18-Sh, 20Kh2N4A-Sh are used, produced by electroslag remelting (ESR). There are no stringy coarse non-metallic inclusions in ESR steel; the metal is dense and homogeneous in macrostructure, has reduced etching in hot and cold states, and has higher mechanical properties compared to steel produced by conventional smelting methods.

Rings and bearings made of corrosion-resistant steel 95X18-Ш after heat treatment in a vacuum have a light surface, and no decarburization is observed, which made it possible to reduce allowances for grinding or, for some surfaces, to cancel this operation altogether.

Heat resistant bearings

When manufacturing bearing parts from steels ШХ15, ШХ15СГ and 95X18-Ш, intended for operation at elevated temperatures (up to 100–150 °C), special heat treatment is usually used.

In this case, ring blanks after forging (or turning from a pipe or rod) are subjected to normalization and accelerated annealing to obtain a structure of homogeneous fine-grained and dotted pearlite.

Improvement of the technology of heat treatment of rolling elements was carried out in two directions: the introduction of high-frequency heating and the use of controlled atmospheres during heat treatment.

Anti-friction powder alloys

The use of powder alloys for the manufacture of antifriction products (bearings, bushings, liners, etc.) operating at low shaft speeds and with a specific load of no more than 1000 MPa, instead of compact antifriction alloys, has a number of advantages.

1. The durability and reliability of bearings increases due to the low coefficient of friction (0.040.07), as well as the content of graphite and pores (1530%) filled with oil in the alloy. Thanks to this, the bearings can operate under difficult conditions, and in some cases for a long time (23 years) without introducing additional lubrication in the presence of oil pockets.
2. The wear of bearings made of porous alloys is 78 times less than the wear of bearings made of cast alloys, and such bearings hardly wear out the shaft journals.
3. Products are produced with increased dimensional accuracy, without further machining, which reduces the cost of bearings and other antifriction parts by 23 times.

When manufacturing bearings from powder antifriction materials, the consumption of expensive non-ferrous materials and alloys is reduced.

Anti-friction parts are most often made from the following porous alloys:

• iron-graphite containing 9299.5% Fe, up to 5% Cu, 0.53% graphite;
• bronze-graphite with a content of 8688% Cu, 9-10% Sn, 2 - 3% C;
• bronze-graphite containing 57.569.5% Cu, 3040% Pb, up to 1% Sn, 0.51.5% C;
• aluminum-lead containing up to 40% Pb, up to 7% Sn, aluminum - the rest, etc.

To improve antifriction properties, these alloys are impregnated with sulfur and other additives.

Ingredient materials for bushings and other antifriction parts have also been created based on non-ferrous metals and graphite.

Brass powders with the addition of large amounts of graphite are used to make valve guides for internal combustion engines that operate without lubrication at a temperature of 430 °C for over 500 hours, corrosion-resistant condenser tubes for shipbuilding, and parts with differentiated properties for electrical and chemical engineering. The use of ingredient porous materials is a promising direction in the production of CCM.

Babbitts

Antifriction alloys based on tin and lead B88 and B83 consist of a soft base of an a-solution of antimony in tin and a p'-phase of solid inclusions SnSb. They are used for the manufacture of bearings operating at sliding speeds of up to 50 m/s and specific pressures of up to 20 MPa.

Bearings made of lead babbit B16, BN and BS6D can operate at sliding speeds of up to 30 m/s, but allow specific pressures of up to 100 MPa; They are used in rolling stock mechanisms in railway transport.

In mechanical engineering, the use of calcium babbitts, containing 0.3-1.5% calcium and 0.1-1.2% cadmium and having higher strength characteristics (δw > 95 MPa) and corrosion resistance, is expanding.

A promising area for using babbitts is the production of bimetallic parts with increased antifriction properties.

Anti-friction zinc alloys

In mechanical engineering, mainly two antifriction zinc alloys are used: TsAM 10-5 and TsAM 9.5-1.5. In addition to aluminum and copper, they contain 0.03-0.06% Mg. Castings of bushings, sliders, monometallic liners, etc. are often made from TsAM 10-5 alloy.

TsAM 9.5-1.5 alloy is used to produce bimetallic strips and parts together with steel and aluminum alloys by rolling.

In deformed form, TsAM 9.5-1.5 is used for bimetallic strips with steel and aluminum alloys by rolling and subsequent stamping of the liner.

Due to their high antifriction properties and sufficient strength, these alloys can replace bronze for friction units whose temperature does not exceed 100 °C.

Source: https://chiefengineer.ru/tehnicheskie-discipliny/materialovedenie/podshipnikovye-materialy-i-tehnologiya-ih-termicheskoy-obrabotki/

Shx15 steel for knives: description, pros and cons

Since time immemorial, the knife has entered human life as a necessity. In ancient times, a knife was a sharpened stone that people used for hunting and protection from predators. Over time, the knife has changed a lot, it has found more and more uses and has become an integral part of everyday life and household use.

Now it is impossible to imagine the life of a modern person without a knife. It has become a necessary tool for cooking, hiking, hunting and fishing, as well as military affairs. Even in sports, the knife has found its use.

How do knives differ from each other?

Nowadays, there are knives of completely different, sometimes even intricate shapes, depending on where they are used. The handle and blade are given the necessary aesthetic and practical appearance. But the deciding factor that differentiates one knife from another is what it was made from. Specifically, we are talking about the chemical composition of the steel from which the blade itself is made.

Not everyone is able to choose exactly the knife steel they need, since there are a huge number of different variations of this alloy, the chemical composition of which determines their properties, advantages and disadvantages, strengths and weaknesses.

But to choose a knife, it is not necessary to study the entire periodic table; it is enough just to know what properties a particular grade of steel has.

By reading a little about it on the Internet, you will quickly find the right alloy for you. In our article we will specifically talk about one alloy that has become quite widespread.

What is ShKh 15 steel?

Steel ШХ 15 is a representative of the class of low-alloy chromium steels . This means that the steel composition, in addition to the main elements, includes special additives. They give it the necessary properties of strength, resistance to corrosion and aggressive environments. ShKh 15 steel contains the following chemical elements:

1. C - 0.95 -1.0.
2. Si - 0.17-0.37.
3. Mn - 0.2-0.4.
4. Cr - 1.35-1.65.

In steels of this group, the amount of chromium is quite small, which is the main difference from high-chromium steels. For this reason, chromium does not form its own carbides, but remains in solid solution and is also part of cementite.

If we talk about structural features, it is worth noting that all carbides are small . This is what determines the high contact endurance and uniformity of this steel.

In general, like other “carbon” steels, ShKh 15 holds a thin edge very well.

This grade of steel is widely used in industry due to its increased hardness, wear resistance and corrosion resistance. It is mainly used to produce rollers and balls for bearings. This is where the name “bearing steel” comes from. Knives made of this steel are characterized by high wear resistance, hardness and contact strength.

ШХ 15 is widely used among knife manufacturers due to the fact that it is perfectly amenable to heat treatment , after which it not only acquires the desired shape, but also improves its strength indicators several times. It also achieves very high wear resistance, which in turn is ensured by the high hardness of the steel. It is worth noting the high resistance to crushing, while maintaining such parameters as ductility and viscosity.

For hardening, the optimal temperature is around 810 - 850 degrees , and the tempering temperature, in turn, varies from 150 to 160 degrees. The final result is a hardness of 61-64 HRC.

Steel of this grade also has a number of the following characteristics: a tendency to temper brittleness or flake sensitivity. The proportionality limit for this material is 370-410 mPa, and the short-term strength limit for this steel is in the region from 590 to 750 mPa. ShKh 15 steel has a relative contraction of 45% and an impact strength characteristic of approximately 440 kJ/m2.

Results

Having studied in detail steel grade ШХ 15, we can clearly indicate its advantages and disadvantages.

Advantages:

• Uniformity.
• High contact endurance.
• Easily processed.
• Fairly high hardness.
• High wear resistance.
• Thin edge when sharpened.
• Resistance to crushing.
• Plasticity and viscosity.

Flaws:

• Relatively high susceptibility to corrosion.
• Difficult to sharpen.

There are many different grades of steel. Each of them has its own advantages and disadvantages. ShKh 15, in turn, is a very versatile steel, suitable for almost any type of knife. At the moment it is one of the most popular brands with low cost and is used mainly in private forging of blades. A product made from such steel can give the desired result from the work, while significantly saving the budget due to its low cost.

Source: https://plusiminusi.ru/stal-shx15-dlya-nozhej-plyusy-i-minusy/

What are bearings made of?

Bearing (from “under the tenon” ) is an assembly unit that is part of a support or stop and supports a shaft, axle or other movable structure with a given rigidity. Fixes the position in space, ensures rotation and rolling with the least resistance, perceives and transmits the load from the moving unit to other parts of the structure [1].

A support with a thrust bearing is called a thrust bearing .

Main parameters of bearings:

• Maximum dynamic and static load (radial and axial).
• Maximum speed (revolutions per minute for radial bearings).
• Landing dimensions.
• Bearing accuracy class.
• Lubrication requirements. [2]
• Bearing life before signs of fatigue appear, in revolutions.
• Bearing noises
• Bearing vibration

The forces loading the bearing are divided into:

• radial , acting in the direction perpendicular to the bearing axis;
• axial , acting in a direction parallel to the bearing axis.

Main types of bearings [ edit | edit code]

Based on the principle of operation, all bearings can be divided into several types:

• rolling bearings;
• plain bearings;

Sliding bearings also include:

The main types used in mechanical engineering are rolling bearings and plain bearings .

Rolling bearings [ edit | edit code]

Rolling bearings consist of two rings, rolling elements (of various shapes) and a cage (some types of bearings may be without a cage), which separates the rolling elements from each other, keeps them at an equal distance and directs their movement. Along the outer surface of the inner ring and the inner surface of the outer ring (on the end surfaces of the rings of thrust bearings), grooves are made - raceways, along which the rolling elements roll when the bearing operates.

There are also loose bearings, consisting of a cage and balls inserted into it (see figure below), which can be pulled out.

There are rolling bearings made without a cage. Such bearings have a larger number of rolling elements and a higher load capacity. However, the maximum rotational speeds of full complement bearings are significantly lower due to increased torques of rotational resistance.

In rolling bearings, rolling friction (there are only small losses due to sliding friction between the cage and the rolling elements), therefore, compared to sliding bearings, energy losses due to friction are reduced and wear is reduced. Closed rolling bearings (with protective covers) require virtually no maintenance (lubricant replacement), open ones are sensitive to the ingress of foreign bodies, which can lead to rapid destruction of the bearing.

Classification [edit | edit code ]

The classification of rolling bearings is based on the following characteristics:

• Ball,
• Roller (needle if the rollers are thin and long);

By type of perceived load

Radial (load along the shaft axis is not allowed).

Radial-thrust, thrust-radial. They absorb loads both along and across the shaft axis. Often the load is along an axis in only one direction.

Thrust (load across the shaft axis is not allowed).

Ball screw drives. Provide screw-nut coupling through rolling elements.

According to the number of rows of rolling elements

Single row,

Double row,

Multi-row;

Self-aligning.

Non-self-aligning.

• According to the material of rolling elements:

• All steel;
• Hybrid (steel rings, non-metallic rolling elements, usually ceramic);

Radial roller bearing

Thrust ball bearing

Thrust roller bearing

Angular contact ball bearing

Angular contact ball bearing with four-point contact

Angular contact roller bearing (tapered)

Self-aligning double row deep groove ball bearing

Self-aligning radial roller bearing

Self-aligning angular contact roller bearing

Self-aligning double row radial roller bearing with barrel rollers (spherical)

Needle bearing roller cage

Ball screw drive

Mechanics [edit | edit code]

The bearing is essentially a planetary mechanism in which the carrier is a cage, the functions of the central wheels are performed by the inner and outer rings, and the rolling elements replace the satellites.

Cage rotation frequency or ball rotation frequency around the bearing axis
nc = n 1 2 ( 1 − D ω dm ) left(1->>
ight)>

where n1 is the rotation frequency of the inner ring of the deep groove ball bearing,
Dω is the diameter of the ball.
dm = 0.5(D+d) - diameter of the circle passing through the axes of all rolling bodies (balls or rollers).

Ball rotation frequency relative to the cage
nsp = n 1 2 ( dm D ω − D ω dm ) left(>>->>
ight)>

Cage rotation frequency when rotating the outer ring
nc ∗ = n 3 2 ( 1 + D ω dm ) left(1+>>
ight)>

where n3 is the rotation speed of the outer ring of the deep groove ball bearing.

For an angular contact bearing
nc = n 1 2 ( 1 − D ω cos ⁡ α dm ) left(1->>
ight)>

nsp = n 1 2 ( dm D ω − D ω cos 2 ⁡ α dm ) left(>>->>
ight)>

From the above relationships it follows that when the inner ring rotates, the separator rotates in the same direction. The rotation frequency of the separator depends on the diameter Dω of the balls at a constant dm: it increases with decreasing Dω and decreases with increasing Dω.

In this regard, the different sizes of balls in the bearing set cause increased wear and failure of the cage and the bearing as a whole.

When the rolling elements rotate around the bearing axis, each of them is subject to a centrifugal force that additionally loads the outer ring raceway.

F c = 0.5 mdm ω c 2,

where m is the mass of the rolling body,
ωс is the angular velocity of the cage.

Centrifugal forces cause overloading of the bearing when operating at high speeds, increased heat generation (bearing overheating) and accelerated wear of the cage. All this reduces the life of the bearing.

In a thrust bearing, in addition to centrifugal forces, the balls are affected by a gyroscopic moment caused by a change in the direction of the axis of rotation of the balls in space

M r = J ω c ω sp

The gyroscopic moment will act on the balls and in the rotating angular contact ball bearing under the action of an axial load

Source: https://ravon-r2.ru/iz-chego-delajut-podshipniki/