Decoding of bearings. Classification and marking of bearings

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

The design of various kinds of modern machines includes many nodes with rotating parts. These are all kinds of levers, wheels, drums. The friction between the parts that occurs in such units can lead to the destruction of materials and the rapid failure of the machine. To prevent this from happening, the rotating elements are connected by bearings.

Details of this type can have different configurations, sizes, and principles of operation. The design features of such products are reflected in their labeling. Deciphering bearings by such designations is extremely simple.

Two main varieties

All products of this type currently used in various kinds of mechanisms can be divided into three large groups. Bearings installed in rotating assemblies:

• slip;
• rolling;
• needle.

All these types of products are in great demand and can be used both in industrial units and in machine tools, cars, etc.

Plain bearings

In parts of this type, friction is reduced bylubrication account. Such bearings may consist of:

• bodies with a hole and a bushing pressed into it;
• from a detachable case and two tabs.

These bearings are made from different materials. Their body is usually made of steel. The sleeve or tabs are most often made of bronze or other similar alloys. Thanks to this design, the friction between the bearing parts is greatly reduced. In order to completely nullify it, grooves are made in the liners of products of this type, into which oil is poured. When the shaft rotates, the latter is pulled under the metal. As a result, an oil film is formed. She lifts the shaft and it is no longer in contact with the liner.

Main advantages and disadvantages

Plain bearings are somewhat easier to manufacture than rolling bearings. They can be used in a variety of nodes. For example, such bearings are often used for electric motors.

The advantages of plain bearings, among other things, include the following advantages:

• quiet operation;
• possibility of use in heavily loaded nodes.

Besides this, the advantage of bearings of this type is that they are very good at eliminating wobble.

But products of this variety, of course, have their drawbacks. The main disadvantage of such bearings is the difficulty in maintenance. In order for such a part to serve for a long time and perform its functions well, it is placed inoil bath or use pumps to supply the oil continuously.

Also, the disadvantages of plain bearings are:

• impossibility of use in highly heated units (oil may ignite);
• need to use expensive non-ferrous metals in construction;
• increased trigger factors;
• oversized in axial direction.

Rolling bearings

Such products are currently more popular than plain bearings. Non-ferrous metals can also be used in such parts, but they are usually still made entirely of steel. Friction in products of this type is reduced due to the presence of metal balls, rollers, cones or, for example, needles in their design. Such elements are placed in rolling bearings in the grooves between the housing and the fixed bearing.

The advantages of this type of product are as follows:

• small costs to overcome friction (a few thousandths of the load on the shaft);
• ease of maintenance.

The oil in such bearings is usually changed only at the next repair of the unit. The disadvantages of products of this type include, first of all, the fact that they cannot bear large axial loads. If too much pressure is applied, the rollers or balls in this type of bearing can easily break.

Needle products

This type of part combines the advantages of rolling and sliding bearings. Between the body and the fixed shaft, in this case, thin long needles of a cylindricalforms. With a slow rotation of the assembly, such a bearing works on the principle of a ball bearing. That is, the needles themselves, along which the body rolls, are responsible for reducing friction in it.

At high speeds, this type of product begins to act as a plain bearing. That is, the needles in it stop rolling and begin to move in a continuous mass along with the oil in a separate layer.

Despite the fact that such parts are, in fact, a combined type, in the classification they are usually referred to as a group of rolling bearings. They are used most often where large or variable loads occur in the nodes. These can be, for example, aircraft engines, giant rolling machines, etc.

Classification of rolling bearings

Such products can be divided into groups according to the following criteria:

• in the direction of perceived load;
• depending on the size ratio;
• on dimensional accuracy and rolling;
• according to the shape of the rolling elements.

Also, these products can be classified according to the method of manufacturing separators. The properties of such parts are reflected in their marking. The decoding of rolling bearings includes, for example, characteristics such as series, type, accuracy class.

Groups by direction of perceived load

In this regard, rolling bearings can be:

• radial;
• stubborn;
• angular contact.

Products of the first variety are the most popular and are used very widely. Radial bearingsperceive mainly the load directed perpendicular to the axis of the shaft.

Thrust products in industry, automotive industry are somewhat less common. Such bearings perceive basically only axial load. Most often, products of this variety are used in metallurgy and engineering.

Thrust-radial bearings are able to take both axial and radial loads. There are at least two rows of rolling elements in such products - in perpendicular planes.

Size classification

In this regard, there are also several groups of similar products. Depending on the size ratio of the inner and outer rings, the classification of bearings is as follows:

• extra light;
• light;
• light wide;
• medium;
• medium-wide.

Also, heavy products of this type can be used in units and mechanisms. Below is a table of sizes of single row ball bearings.

Depending on the series, in this case, with the same diameter of the inner ring, the diameter of the outer one or its width may vary. By width, rolling bearings are classified into:

• especially narrow;
• narrow;
• normal;
• wide;
• extra wide.

The ball bearing size chart above is for light and medium series.

Classification byaccuracy

Rolling bearings are installed in the nodes on which the efficient operation of the entire mechanism as a whole depends. At the same time, such products are manufactured in compliance with the standards stipulated by GOST. Rolling bearings in terms of accuracy can be classified by:

• size;
• rotation parameters.

In the first case, the quality of the product is determined by the deviations of the outer and inner diameters, as well as the width of the rings. Rotational accuracy is measured by the degree of runout in the radial and lateral directions. Currently, the following classes of rolling bearings are distinguished in this respect:

• 0 - normal with inner ring runout (up to 20 µm);
• 6 - increased accuracy with runout (up to 10 microns);
• 5 - high accuracy with runout (up to 5 µm);
• 4 - especially high accuracy (up to 3 microns);
• 2 - ultra-high precision (up to 2.5 microns).

The industry also produces coarse, with a runout of over 20 microns, rolling bearings of class 7 and 8. The price for such products is determined mainly by the class of rotation accuracy. The higher it is, the more expensive the bearing costs.

Classification according to the shape of rolling elements

Depending on the shape, the details may also differ. Most often in industry and automotive industry, ball bearings are used. GOST defines both their dimensions and accuracy class. Such products are considered the most simple to manufacture and high-speed. These bearings allow, among other things, a rather large angular velocity. Their main advantage islow cost. The disadvantages of bearings of this type include the fact that they cannot carry a significant load.

Roller products have increased load capacity and are able to withstand shock loads well. However, such products absolutely do not allow shaft distortions. In this case, the rollers begin to work with edges, which leads to rapid wear of the bearing. Parts of this type can work several times longer than ball parts.

Products with twisted rollers are very undemanding to assembly accuracy. They are used in cases where radial loads of the impact type occur in the node. Bearings of this variety are usually small in size.

Tapered roller bearings are used in applications where both radial and unilateral axial loads act simultaneously. Install them at medium and low shaft speeds. Such products are used mainly in the same cases as thrust radial ball bearings. GOST, of course, determines the dimensions of such parts.

Self-aligning bearings are used when the misalignment of the rings can reach up to 2-3 degrees. Among other things, such products allow a slight axial load.

In the design of the simplest bearings, there is only one row of rolling elements. But in the industry, more complex products of this type can also be used - 2-4 in-line.

Sometimes in various kinds of nodes and mechanisms can be installed and rolling bearings of a special design - ringless. For such body productsrollers are located directly between the housing and the shaft. The disadvantage of such structures is, of course, primarily the complexity of assembly and disassembly.

Transcript

Deciphering rolling bearings is essential to determine its characteristics. In order for the consumer to be able to purchase for himself exactly the bearing that he needs, such products are designated by manufacturers in a special way. In the marking of such products there are always several numbers by which you can determine its class and series.

Decoding of rolling bearings is carried out, according to the standards, from right to left. The first and second digits indicate the internal diameter of the product. To determine the actual size, simply multiply this number by 5.

Based on the third digit, you can find out the outer diameter of the bearing, that is, its series. The latter are designated as:

• ultralight - 8 or 9;
• extra light - 1 or 7;
• light - 2 or 5;
• medium - 3 or 6;
• heavy - 4.

The fourth digit from the right in the marking can be used to decipher the type of rolling bearing:

• 0 - radial single row ball;
• 1 - double-row radial ball;
• 2 - radial with cylindrical short rollers;
• 3 - double-row radial roller;
• 4 - needle;
• 5 - radial with twisted rollers;
• 6 - angular contact ball;
• 7 - angular contact roller taper;
• 8 - thrust ball;
• 9 - thrust roller.

Fifth and sixth digits from the right can be used to determine the design features of the bearing that do not have a significant impact on its performance. Such products can be, for example, non-separable, have a protective washer, a groove on the outer ring, etc.

The seventh digit on the right in the marking characterizes the bearing series in width.

Of course, when buying, you can easily find out the accuracy class of such a product. Deciphering the designations of domestic bearings on this basis is also an absolutely simple matter. To the left of the considered series of numbers in the marking of such parts through the dash there is another number. It is on it that accuracy is determined.

Bearings of a class from 0 to 6 can be used in various kinds of nodes. At the same time, normal products of this type, marked with the number 0, are most often used. In parts operating at high frequency, very high-quality bearings are usually used, marked 4-5. Class 2 products are most often used in hygroscopic instruments.

Notation example

So, deciphering the marking of ball bearings or any other is extremely simple. The brand in products of this type is applied to one of the rings. On collapsible bearings, it is affixed to both parts.

The parameters of a product marked, for example, 67210 will be as follows:

• diameter - 105=50mm;
• 2 - light series;
• 7 - angular contact conical;
• 6 - diametral gap along the main row.

Decodingbearing by number is usually produced in this way. Since nothing is indicated on the left through a hyphen in the marking of this product, its accuracy class will be zero. But for other bearings, its designation, of course, can be affixed.

Plain bearing classes

Such products can be classified by:

• load direction;
• principle of the occurrence of lift in the oil layer;
• case type.

According to the first feature, such products are classified into radial and thrust. Like rolling bearings, parts of this type can take the load radially or in the axial direction. In some cases, the nodes use products of this variety with combined supports. For these bearings, axial loads occur on special ridges or shell ends.

Classification based on lift principle

In this regard, plain bearings are distinguished:

• hydrodynamic;
• hydrostatic.

In the first case, excess pressure in the oil layer is formed due to its penetration into the wedge gaps during the relative movement of the surfaces. Such bearings have a fairly simple design. Hydrostatic products are different in that oil pressure is created in them when the pump is running.

Varieties by body type

The simplest bearings of this type - deaf - have in their design a one-piece pressed sleeve made of anti-friction material. Also detachable products of thisvarieties. For such plain bearings, a split sleeve is installed between the cover and the housing, connected by bolts. It is believed that products of this type are more convenient to use.

What kind of liners can be

This structural element of plain bearings is most often, as already mentioned, made of bronze. However, the industry also produces such products with bushings made of steel or cast iron with an additional layer of anti-friction alloy.

Lubrication Modes

In order for a plain bearing to work long and efficiently, it often has to be serviced almost daily. Such products need lubrication regularly. The following types of products can be used for plain bearings:

• liquid mineral and synthetic oils;
• calcium sulfonate or lithium soap based greases;
• solid - molybdenum disulfide, graphite.

Gasostatic bearings can also be used in various units and mechanisms. In such products, nitrogen or inert gases replace the lubricant. Products of this type are usually used in lightly loaded mechanisms.

Actually, there are three modes of lubrication of plain bearings:

• boundary;
• semi-liquid;
• liquid.

In the first case, the lubrication of the contact surfaces occurs due to the oil film formed on the fixed shaft on the surface of the trunnion. Boundary lubrication is considered an ineffective variety. Atits use inside the bearing is the contact of a large number of irregularities. In addition, when using this method, the viscosity of the oil is lost.

At the time of the semi-fluid lubrication method, an oil layer is formed between the journal and the bushing as the shaft rotates. In this case, the contact of irregularities in the bearing practically does not occur. The shaft using this technique floats up under the buoyant force of the oil.

When using a liquid lubrication technique, the bearing shell and journal are completely separated by an oil layer. Contact of microroughnesses in this case does not occur at all. Therefore, this lubrication technology can be considered the most effective.

Imported bearings

Products of this type are made all over the world to almost the same standard. Imported bearings to the units of mechanisms used at the enterprises of the Russian industry usually fit just as well as domestic ones. But products supplied from abroad are labeled, of course, in a completely different way. The brand on such parts usually contains several numbers and Latin letters. Deciphering the designations of imported bearings can be done according to special tables.

For example, bearing designations FAG 6203-C-2RSR-TVH-L178-C mean the following:

• 6203 - standard size (17х40х12);
• 2RSR - the bearing has a rubber-metal seal on both sides;
• TVH - this product's cage is made of polyamide;
• L178 - marking for the type and amount of usedlubricants;
• C3 - means that this bearing has increased radial clearance.

Of course, foreign companies supply bearings of various types to the domestic market. But the most popular in Russia are still imported ball, roller and needle bearings.

Which countries can be produced in

Most often, domestic products of this type can be found on sale in our country. The second most common bearings in the Russian market are bearings of the manufacturing country China. We also sell parts manufactured in Europe in our country.

The answer to the question of which bearing companies are better is unambiguous - first of all, these are European manufacturers. For example, products of this type, supplied to the Russian market by such companies as SKF (Sweden), NTN Corp (Japan), The TimkenCompany (USA), deserved good reviews from consumers.