Help on Tele2, tariffs, questions

Grinding wheels are designed to remove small amounts of material from the surface of a workpiece. In this way, irregularities are removed and sharpening is performed. various instruments. To select a particular model, you should familiarize yourself with the classification and types of grinding wheels.

Purpose of grinding wheels

The scope of application of these processing tools is wide. They differ not only appearance, but also the manufacturing method. Using grinding wheels, you can remove a small amount from the surface of the workpiece, thereby improving the technical and operational characteristics and appearance.

Many materials and tools fall under the definition of a grinding wheel. Therefore, it is advisable to consider the most common of them. For domestic purposes, end-mounted ones are most often used, which are installed on a drill. In addition, you should take into account the product labeling, the possibility of use on special sharpening machines, size.

Methods of using grinding wheels depending on marking and composition:

• grinding the surfaces of various parts and workpieces. The degree of processing depends on the grain size, total contact area and rotation speed;
• sharpening of tools. To perform these actions, you must use special diamond sharpeners.

During selection, the material of the workpiece is taken into account. Various types of grinding wheels are used to process wood, steel and polymer surfaces with a drill.

To perform certain types of work, grinding wheels of non-standard configurations and sizes are sometimes required. In other models they differ not only in grain size, but also in shape. More often similar models used to complete factory machines.

Types of grinding wheels

To determine the types of grinding wheels, you need to familiarize yourself with GOST 2424-83. It indicates the area of ​​purpose, material of manufacture and requirements for technical parameters this type of instrument. But the operating conditions are the determining factor.

Currently, the following types of face and plane wheels with appropriate markings and designations can be used to perform grinding work:

• grinding for metal. Used for processing welded joints. After installation on the drill, the end part processes workpieces and parts;
• diamond Designed for final grinding of the workpiece surface. It should be remembered that they belong to the category of sharpening ones. Characterized by a special composition;
• fiber. Made from multi-layer vulcanized paper. Processing occurs with both the end and planar parts of the material. Designed for installation on a drill;
• petal. They consist of many petals mounted on a mounting ring. They are characterized by high adaptability to any type of workpiece surface. Flap discs effectively remove rust;
• self-hinging. Characterized by high rate graininess. One part has an adhesive backing for installation on a drill. Designed for fine processing of wooden or metal surfaces.

Before choosing, consider the grain size grinding discs. The same applies to sharpening models. The larger the grain size, the more intensively material will be removed from the surface of the part during sharpening.

The diameter is also taken into account. For household machines, models with a diameter from 50 to 300 mm are used. During fine machining, specially shaped wheels can be installed.

Material for making sharpening grinding wheels

The degree of processing of a grinding wheel largely depends on its structure. Considering the different types of operations, manufacturers offer several types for drills, differing in markings, material of manufacture and type of processing - face or plane.

The main requirement for the manufacturing material is abrasive properties. At the same time, they must have sufficient mechanical strength and not be destroyed under the influence of aggressive environments. The latter quality is especially important when using coolants. This is not typical for petal models.

The structure and composition of the manufacturing material can be determined by markings and designations. The scope of application of the grinding wheel is also indicated there:

• electrocorundum They are divided into white (22A, 23A, 24A, 25A), normal (12A, 13A, 14A, 15A, 16A), chrome (32A, 33A, 34A), titanium (37A) and zirconium (38A). The higher the number, the higher the quality of workmanship;
• silicon carbide. Manufactured in green (62С, 63С, 64С) and black (52С, 53С, 54С, 55С) colors. The first has a more fragile structure. Used as sharpening tools;
• diamond. The main area of ​​application is sharpening and grinding of carbide tools. Diamond wheels can be used to polish other types of grinding surfaces;
• elbor. Its properties are similar to diamond, but it is more heat resistant. It is practically not used as a sharpener for household needs, as it is expensive.

The next property of end wheels for drills is their grain size. It determines the cleanliness of the resulting surface. In the old GOST, the main characteristic was grain size. This characteristic can vary from 20 to 200 microns. Grit size according to GOST 52381-2005 is designated Fx (where x is a characteristic of the grain size). The higher this value, the smaller size particles.

In each specific case, the material of manufacture of the grinding wheel for face machining using a drill is determined in accordance with individually. This is influenced by the properties of the workpiece and the required degree of grinding.

Marking of main grinding wheels

In order to choose the optimal grinding wheel model, you need to know the symbols on its surface. In this way, you can find out not only the method of its manufacture, but also the grain size, exact dimensions and configuration: petal, regular or special sharpening.

First of all, you should determine the material of manufacture and the possibility of using it as a sharpener on a machine. Data can be taken from the list described above. Then the grain size of the drill wheel is determined. In some cases, the pictogram indicates that face machining is not possible. Most often this concerns corundum discs for metal.

The next property is the hardness of the grinding wheel. Classification depending on its composition:

• F, G. Classified as very soft;
• H, I, J. Soft, designed for finishing parts;
• K, L. Products with medium softness are marked in this way;
• M, N. Medium, the most common type;
• O, P, Q. Medium hard;
• R, S. Solid;
• T, U. Very hard, used as a sharpener;
• V, W, X, Y, Z. Extremely hard.

Manufacturers rarely indicate the structure and composition of the disc on the label. First of all, this relates to the type of connection. This term indicates what composition was used to create a homogeneous mass. Currently, ceramic, bakelite and vulcanite binders can be used as a binding component.

During operation, the geometry of the oval circle or the size of the petal base may be disrupted. This is especially true for face machining of parts using a drill or machine. In this case, it is necessary to make changes according to the marking. To do this, it is recommended to use carbide tools or diamond discs.

The video shows the main types of grinding wheels:

Grinding wheels are characterized by geometric shape (type), type of abrasive material, its grain size, bond type, hardness, etc. And when choosing a grinding wheel, such characteristics as the degree of hardness or structure may be more significant than the type of abrasive.

The complete markings for grinding wheels contain:

• circle type;
• its dimensions;
• type of abrasive material;
• grit number;
• degree of hardness;
• structure (the relationship between the abrasive, bond and pores in the body of the tool);
• type of ligament;
• maximum speed;
• accuracy class;
• imbalance class.

The marking of wheels, made in accordance with various editions of GOSTs, has some differences regarding the designations of grain size, hardness, grade of abrasive and binder. Manufacturers label their wheels differently, using old or new designations and excluding certain characteristics. Below are examples of deciphering the designations of grinding wheels.

3 - hardness: K - medium-soft;
4 - structure: 6 - medium;

6 - imbalance class: 2

1 - abrasive material: 25A - white electrocorundum;
2 - grain size (old marking): 60 (according to GOST it should be 63) - 800-630 microns;
3 - hardness: K-L - depending on the circumstances, it can be K or L - medium-soft;
4 - ligament: V - ceramic.

1 - abrasive material: 25A - white electrocorundum;
2 - grain size (old marking): 25 - 315-250 microns;
3 - hardness (old marking): SM2 - medium-soft;
4 - structure: 6 - medium;
5 - bond (old marking): K - ceramic;
6 - accuracy class: B
7 - imbalance class: 3

1 - abrasive material: 25A - white electrocorundum;
2 - grain size: F46 - average size 370 microns;
3 - hardness: L - medium-soft;
4 - structure: 6 - medium;
5 - bond: V - ceramic;
6 - peripheral speed: 35 m/s;
7 - accuracy class: B
8 - imbalance class: 3

1 - abrasive material: 14A - normal electrocorundum;
2 - grain size: F36-F30 - extended range including F36 (average size 525 microns) and F30 (average size 625 microns);
3 - hardness: Q-U - depending on the circumstances, it can be medium-hard, hard, very hard;
4 - bond: BF - bakelite with reinforcing elements;
5 - imbalance class: 1

The choice of grinding wheel brand should be made taking into account all its characteristics.

Types of grinding wheels and their sizes

The following types of grinding wheels are produced (in parentheses the designations according to the old GOST 2424-75 are given):

• 1 (PP) - straight profile;
• 2 (K) - ring;
• 3 (3P) - conical;
• 4 (2P) - double-sided conical;
• 5 (PV) - with one-sided groove;
• 6 (CHTs) - cup cylindrical;
• 7 (LDPE) - with two grooves;
• 9 - with double-sided groove;
• 10 (PVDS) - with double-sided groove and hub;
• 11 (CHK) - conical cup;
• 12 (T) - disc-shaped;
• 13 - disc-shaped;
• 14 (1T) - disc-shaped;
• 20 - with one-sided conical groove;
• 21 - with double-sided conical groove;
• 22 - with a conical recess on one side and a cylindrical recess on the other;
• 23 (PVK) - with conical and cylindrical grooves on one side;
• 24 - with conical and cylindrical recesses on one side and a cylindrical recess on the other;
• 25 - with conical and cylindrical recesses on one side and conical on the other;
• 26 (PVDK) - with conical and cylindrical recesses on both sides;
• 27 - with a recessed center and reinforcing elements;
• 28 - with a recessed center;
• 35 - straight profile, working with the end;
• 36 (PN) - with pressed-in fasteners;
• 37 - ring with pressed fasteners;
• 38 - with one-sided hub;
• 39 - with a double-sided hub.

All types are described in GOST 2424-83.

In addition to the profile shape, circles are characterized by the size DxTxH, where D is the outer diameter, T is the height, H is the diameter of the hole.

Types of diamond and CBN wheels are regulated by GOST 24747-90. The marking of the shape of CBN and diamond wheels consists of 3 or 4 characters that carry information about the cross-sectional shape of the body, the cross-sectional shape of the CBN-containing or diamond-bearing layer, the location of the latter on the wheel, and the design features of the body (if any).

Designation of a grinding wheel with a body shape 6, the shape of a diamond-bearing or CBN-containing layer A, with the location of a diamond-bearing or CBN-containing layer 2, with design features building S.

All types are described in GOST 24747-90.

The type and size of the wheel are selected based on the type and configuration of the surfaces being ground, as well as the characteristics of the equipment or tool used.

The choice of wheel diameter usually depends on the spindle speed on the selected machine and on the ability to provide an optimal peripheral speed. Specific wear will be the least with the largest diameter circle size. Smaller wheels have fewer grains on the working surface, each grain has to remove more material, and therefore they wear out faster. When working with small diameter wheels, uneven wear is often observed.

When choosing diamond wheel It is advisable to pay attention to the width of the diamond-bearing layer. When working "on the pass" it should be relatively large. When grinding using the plunge-in method, the width diamond sputtering should be commensurate with the width of the surface being treated. Otherwise, ledges may appear on the surface of the circle.

Abrasives

The most commonly used abrasive materials for grinding wheels are: electrocorundum, silicon carbide, CBN, diamond.

Electrocorundum Available in the following brands: white - 22A, 23A, 24A, 25A(the higher the number, the higher the quality); normal - 12A, 13A, 14A, 15A, 16A; chromium - 32A, 33A, 34A; titanic - 37A; zirconium - 38A and others.

Silicon carbide. There are two types of silicon carbide available: black - 52C, 53C, 54C, 55C and green - 62С, 63С, 64C, differing from each other in some ways mechanical properties and color. Green carbide is more fragile than black carbide.

Diamond widely used for the manufacture of diamond grinding wheels used for finishing and sharpening carbide tools, processing parts made of hard alloys, optical glass, ceramics, etc. It is also used for dressing grinding wheels made of other abrasive materials. When heated in air to 800°C, diamond begins to burn.

Elbor(CNB, CBN, borazone, cubonite) is a cubic modification of boron nitride. Having the same hardness as diamond, it is significantly superior to the latter in heat resistance.

Abrasive materials are characterized by hardness, granularity, abrasive ability, strength, heat and wear resistance. High hardness is the main distinctive feature abrasive materials. Below are comparative characteristics on microhardness and heat resistance of basic abrasive materials.

The choice of one or another abrasive material is largely determined by the characteristics of the material being processed.

Diamond wheels are capable of processing material of any hardness. However, you need to keep in mind that diamond is very fragile and does not withstand shock loads well. Therefore, it is advisable to use diamond wheels for final processing of carbide tools, when it is necessary to remove a small layer of material and there is no shock load on the grain. In addition, diamond has relatively low heat resistance, so it is advisable to use it with a coolant.

Grain

Abrasive grain size is a characteristic of grinding wheels that determines the cleanliness of the resulting surface. The grain is either an intergrowth of crystals, or a separate crystal, or its fragments. Like all solids, it is characterized by three dimensions (length, width and thickness), but for simplicity they operate with one - width. Many parameters depend on the grain size - the amount of metal removed in one pass, the cleanliness of the processing, grinding performance, wheel wear, etc.

According to GOST 3647-80, in the designation of the grain size of grinding wheels, the grain size is indicated in units equal to 10 microns (20 = 200 microns), for micropowders - in microns with the addition of the letter M.

In the new GOST R 52381-2005, which basically corresponds to the international standard FEPA, the grain size of grinding powders is indicated by the letter F with a number. The higher the number, the finer the grain and vice versa.

Diamond and CBN wheels have their own grain size designations. Their grain size is indicated by a fraction, the value of the numerator of which corresponds to the size of the side of the upper sieve in microns, and the denominator - the value of the lower sieve.

The table below shows the ratios of grinding wheel grit according to old and current standards.

The choice of wheel grain size should be determined by a number of factors - the type of material being processed, the required surface roughness, the amount of allowance to be removed, etc.

The smaller the grain size, the cleaner the processed surface is. However, this does not mean that finer grain size should be preferred in all cases. It is necessary to choose the grain size that is optimal for a particular processing. Fine grain gives a higher surface cleanliness, but at the same time can lead to burning of the processed material and clogging of the wheel. Using fine grains reduces grinding performance. In general, it is advisable to choose the largest grain size provided that the required cleanliness of the treated surface is ensured.

If it is necessary to reduce surface roughness, the grain size must be reduced. Larger allowances and increased productivity require larger grits.

In general, the harder the material being processed and the lower its viscosity, the higher the wheel grit can be.

Hardness of grinding wheels

The hardness of the grinding wheel should not be confused with the hardness of the abrasive material. This different concepts. The hardness of the grinding wheel characterizes the ability of the bond to hold abrasive grains from being torn out under the influence of the material being processed. It depends on many factors - the quality of the bond, the type and shape of the abrasive, and the wheel manufacturing technology.

The hardness of a wheel is closely related to self-sharpening - the ability of an abrasive wheel to restore its cutting ability by destroying or removing dull grains. During operation, the wheels intensively self-sharpen due to the splitting of the cutting grains and their partial chipping out of the bond. This ensures that new grains enter into the work, thereby preventing the appearance of burns and cracks in the material being processed. The lower the hardness of the wheel, the higher the self-sharpening ability. Based on hardness, circles are divided into 8 groups.

The choice of grinding wheel hardness depends on the type of grinding, the accuracy and shape of the parts being ground, physical and mechanical properties processed material, type of tool and equipment. In practice, in most cases, medium-hard wheels are used, which have a combination of relatively high performance and sufficient durability.

A slight deviation of the wheel characteristics from the optimal one leads either to burns and cracks of the sharpened surface, when the hardness of the wheel is higher than required, or to intense wear of the wheel and distortion of the geometric shape of the sharpened tool, when the hardness of the wheel is insufficient. Wheels for sharpening tools with inserts made of hard alloys must be selected with particular precision in terms of hardness.

Here are some recommendations that may be useful when choosing grinding wheels based on hardness. When sharpening tools with carbide cutters, the wheel must have high self-sharpenability. Therefore, when sharpening them, wheels of low degrees of hardness are used - H, I, J (soft), less often K. The more tungsten or titanium carbides in the hard alloy, the softer the grinding wheel should be.

When it is required to maintain high precision of shape and size, preference is given to those types of grinding wheels that have increased hardness.

When using cutting fluids, grinding uses harder wheels than when grinding without cooling.

Wheels on a bakelite bond should have a hardness 1-2 levels higher than wheels on a ceramic bond.

To prevent burns and cracks, softer circles should be used.

Structure

The structure of a tool is usually understood as the percentage of the volume of abrasive material per unit volume of the tool. The more abrasive grain per unit volume of the wheel, the denser the structure of the tool. The structure of the abrasive tool affects the value free space between grains.

When sharpening cutting tools, it is advisable to use wheels with more free space between the grains, as this makes it easier to remove chips from the cutting zone, reduces the possibility of burns and cracks, and facilitates cooling of the tool being sharpened. For sharpening cutting tools, wheels on a ceramic bond of 7-8th structure are used, on a bakelite bond - 4-5th structure.

Bunch

In the manufacture of grinding wheels, abrasive grains are bonded to the base and to each other using a bond. The most widely used binders are ceramic, bakelite and vulcanite.

Ceramic bond It is made from inorganic substances - clay, quartz, feldspar and a number of others by grinding them and mixing them in certain proportions. The marking of ceramic bonded grinding wheels contains the letter ( V). Old designation - ( TO)

The ceramic bond gives the abrasive tool rigidity, heat resistance, shape stability, but at the same time increased fragility, as a result of which it is undesirable to use wheels with a ceramic bond under shock loads, for example, during rough grinding.

Bakelite bond mainly consists of an artificial resin - bakelite. The marking of circles with bakelite has in the designation Latin letter (B). Old designation - ( B). Compared to ceramic, bakelite binder has greater elasticity and elasticity, heats the metal being processed less, but has lower chemical and temperature resistance, and worse edge resistance.

The bakelite bond can be with reinforcing elements ( B.F., old designation - BOO), with graphite filler ( B4, old designation - B4).

Vulcanite bond is a vulcanized synthetic rubber. The abrasive wheel is marked with the letter ( R). Old designation - ( IN).

In most cases they are used abrasive wheels on ceramic or bakelite bonds. Both have their own characteristics, which determine their choice for a particular job.

The advantages of a ceramic binder include strong fixation of grain in the binder, high thermal and wear resistance, good preservation working edge profile, chemical resistance. The disadvantages are increased fragility, reduced bending strength, high heat generation in the cutting zone, and, consequently, a tendency to burn the material being processed.

The advantages of the bakelite bond are elasticity, good self-sharpening of the wheel due to the reduced strength of grain fixation in the bond, and reduced heat generation. Disadvantages: more intense wear compared to ceramic bond, reduced edge resistance, low resistance to coolants containing alkalis, low heat resistance (bakelite begins to become brittle and burn out at temperatures above 200°C).

Accuracy class

The accuracy of the dimensions and geometric shape of abrasive tools is determined by three classes AA, A And B. For less critical abrasive processing operations, a class tool is used B. A class instrument is more accurate and of higher quality A. To work in automatic lines, high-precision tools are used on high-precision and multi-circle machines AA. It is more different high accuracy geometric parameters, uniformity of grain composition, balance of abrasive mass, made from the best varieties grinding materials.

Unbalance class

The imbalance class of a grinding wheel characterizes the imbalance of the wheel mass, which depends on the accuracy of the geometric shape, the uniformity of mixing of the abrasive mass, the quality of pressing and heat treatment of the tool during its manufacturing process. Four classes of permissible imbalance of the mass of circles have been established ( 1 , 2 , 3 , 4 ). Unbalance classes have nothing to do with the accuracy of balancing the wheels and flanges before installing them on the grinding machine.

When using the content of this site, you need to put active links to this site, visible to users and search robots.

is an abrasive tool consisting of grains of a certain fraction cemented together binder. It is a body of rotation with a standard outer and inner diameter, with a certain surface configuration optimal for performing certain operations.

Scope of application

Grinding wheels are used for preliminary and finishing products made of ferrous and non-ferrous metals, plastic, wood and other materials. The area of ​​application of the wheel is determined by its grain size, diameter and surface shape. Using a circle, it is possible to process flat and shaped surfaces, ends, threads, holes, etc.

The main area of ​​application of grinding wheels is mechanical engineering and machine tool construction. Depending on the geometry, they can be used as equipment for sharpening machines, hand-held electric or pneumatic tools. They can also be used for manual operations. Wide choose The tool allows you to carry out a wide range of operations - from peeling and rough finishing to final grinding and polishing.

Grit size of grinding wheels

Grit size is one of the main parameters for choosing a grinding wheel for certain operations. It is determined by the grain size of the fraction divided into fractions in accordance with the group of grinding material and is indicated by the corresponding numerical value.

There are three main groups - grinding grain, grinding powders and micro-grinding powders. In the first two groups, grain size is determined by the smallest grain fraction in hundredths of a millimeter. So, for example, 40 means a fraction size of 400 microns or 0.4 mm. In the third group, micro-grinding powders, the numerical value determines the largest grain size in the fraction in microns and has the additional designation M. For example, M20 is a circle with largest size grains in a fraction of 20 microns.

The table below shows data on the grain size of the groups in accordance with GOST 3647-80 and the international standard ISO 8486.

Profile

The profile of a wheel determines whether it can be used for certain operations. We list the most commonly used types of profiles:

• Flat with a straight profile – internal or centerless grinding, torus processing and other operations.
• Flat double-sided with a conical profile – processing of gears and simple threads.
• Flat with undercut – cylindrical grinding, end trimming.
• Cylindrical and conical wheels – sharpening of tools and other operations.
• Disc wheels – sharpening of tools with multiple cutting blades.

Marking

The main parameters of the circle can be determined by its symbol, which is indicated in the product labeling. Symbol corresponds to GOST R 52781 and it states:

• circle type;
• material;
• grain;
• geometric parameters (outer and inner diameters, height);
• type of ligament;
• structure and degree of hardness;
• the highest permissible processing speed.

The exception is wheels with individual markings, which have wheels from foreign manufacturers. When purchasing this product, you must study the information in the catalogs and on the packaging.

Selection rules

The main factor in choosing a grinding wheel is the parameters of the material being processed and the scope of application (machine, hand tool). Another important factor– this is the quality of processing determined by the grain size of the wheel. The larger the grain size, the higher the surface layer removal rate, but the lower the surface quality. For this reason, fine-grit wheels are used for fine grinding.

The table below provides data on the choice of grit depending on the grinding operation.

It is desirable that the circle matches the material for which it is intended. This is indicated in the manufacturer's recommendations, in particular in the form of an image on the label. Pay attention to the permissible rotation speed, which is an important condition work safety.

GOST standards

The operation and technical conditions of grinding wheels are regulated by a number of Russian and international GOSTs. In particular:

• GOST 3647-80 and the corresponding ISO 8486 regulate the grain size of the wheels.
• GOST R 52588-2011 – defines the safety requirements for the tool.
• GOST R 52781 – regulates the technical conditions of grinding wheels.

There are other standards that define the parameters various types grinding wheels.

If you have 1A1 250x40x34 24A F30 L 5 V 35 B 3 written on your grinding wheel, then I think after reading it you can easily decipher it

Grinding wheel shapes

250x40x34 24A F30 L 5 V 35 B 3
For cylindrical grinding, the wheel must have profile A1A or 1V1. In Soviet circles it was designated PP or 1.

Grinding wheel geometry

1A1 250x40x34 24A F30 L 5 V 35 B 3

250 is the diameter of the grinding wheel
40 is the thickness of the grinding wheel
34-hole diameter in the grinding wheel

Abrasive and grinding wheel grain

1A1 250x40x34 24A F30 L 5 V 35 B 3

All grinding wheels consist of two main components - the grinding grains that actually cut and the bond that holds and holds them together during the cutting process. Ratio of grain to free space andligaments in the wheel characterize the structure of the grinding wheel.

An ideal abrasive should remain sharp with a minimum number of sharp edges, and when dull, the abrasive of the grinding wheel should chip off, renewing fresh cutting edges.
Aluminum Oxide - This abrasive is used for grinding carbon steel and alloys, high speed steel, annealed ductile iron, wrought iron, bronze. It happens to be white - 22A, 23A, 24A, 25A(the higher the number, the higher the quality) and normal -12A, 13A, 14A, 15A, 16A; chromium - 32A, 33A, 34A; titanic - 37A. Foreign manufacturers of grinding wheels have the following designation:

A brown alumina, WA white alumina
WAB white aluminum oxide + blue bond
W.A. white aluminum oxide + special bond
WAR white aluminum oxide + red bond
WAY white aluminum oxide + yellow bond
PA pink aluminum oxide
R.A. ruby aluminum oxide
D.A. white and brown aluminum oxide
S.A. semi-brittle aluminum oxide
H.A. monocrystalline aluminum oxide
WITH black silicon carbide

Zirconium aluminum oxide - this abrasive is used for grinding in rough grinding, designated 38A or Z.
Silicon carbide - this abrasive is used for grinding gray and white cast iron, soft bronze, brass and aluminum and non-metallic materials, designated64С-62С or G.C..

Ceramic aluminum oxide - this abrasive is used for precision grinding of difficult-to-cut steels and alloys, designated AS1-5, the higher the number, the greater the aluminum oxide content, for example 1 is 10%.

Grain size is the number of linearly spaced holes in one inch of screen used for final screening of grain. The larger the grain size, the coarser the grain. The smaller the grain size, the more suitable the wheel is for fine grinding.

Grinding wheel grain size

1A1 250x40x34 24A F 30 L 5 V 35 B 3

Large from 8 before 24 (F 180-80)
Average from 30 before 60 (F 56-24)
Small from 80 before 180 (F 24-12)
Very fine from 220 before 600 (F 10-4)

Hardness of grinding wheels

1A1 250x40x34 24A F30 L 5 V 35 B 3

Bond hardness is measured in terms of the hardness of the grinding wheel. For example, the bond has a hard grade if the bond between the abrasive grains of the grinding wheel is very strong, and it well keeps the grains from being pulled out under the action of cutting forces during grinding. Conversely, the bond has a soft degree if the application of a small force is enough to pull the grains out of the circle.
Hard wheels are used for machining work with a small contact area. Soft grinding wheels are used for fast and coarse material removal and for processing hard materials.

Grinding Wheel Structure

1A1 250x40x34 24A F30 L 5 V 35 B 3

The structure of a tool is usually understood as the percentage of the volume of abrasive material per unit volume of the tool. The more abrasive grain per unit volume of the wheel, the denser the structure of the tool. The structure of the abrasive tool affects the amount of free space between the grains.

With knitting grinding wheel

1A1 250x40x34 24A F30 L 5 V 35 B 3

The bond in the grinding wheel is designed to hold the abrasive grains together and should facilitate the process of self-sharpening of the grains.
The choice of the type of grinding wheel bond affects the processing speed, its type and accuracy.

Ceramic bond It is made from inorganic substances - clay, quartz, feldspar and a number of others by grinding them and mixing them in certain proportions. The marking of ceramic bonded grinding wheels contains the letter ( V). Old designation - ( TO)

The ceramic bond gives the abrasive tool rigidity, heat resistance, shape stability, but at the same time increased fragility, as a result of which it is undesirable to use wheels with a ceramic bond under shock loads, for example, during rough grinding.

Bakelite bond mainly consists of an artificial resin - bakelite. Marking of circles with bakelite has a Latin letter ( B). Old designation - ( B). Compared to ceramic, wheels with a bakelite bond have greater elasticity and elasticity, heat the metal being processed less, but have less chemical and temperature resistance.

The bakelite bond can be with reinforcing elements ( B.F., old designation - BOO), with graphite filler ( B4, old designation - B4).

Vulcanite bond is a vulcanized synthetic rubber. The abrasive wheel is marked with the letter ( R). Old designation - ( IN)

Grinding wheel accuracy class

1A1 250x40x34 24A F30 L 5 V 35 B 3

The accuracy of the dimensions and geometric shape of abrasive tools is determined by three classes AA, A And B. For less critical abrasive processing operations, a class tool is used B. A class instrument is more accurate and of higher quality A. High-precision tools are used to work in automatic lines, on high-precision and multi-circular machines AA. It is distinguished by higher accuracy of geometric parameters, uniformity of grain composition, balance of abrasive mass, and is made from the best grades of grinding materials.

Grinding wheel grit

The grain size of the grinding wheel affects the quality of the resulting surface when grinding a surface, for example, the finer the grain of the wheel, the higher the surface roughness class.
The grit size of the grinding wheel is selected depending on the type of grinding operation: rough, semi-finishing or finishing, as well as the necessary requirements for cleanliness and precision of processing. During the rough grinding operation, wheels made of larger grains are used than during finishing. High demands on the cleanliness of the resulting surface and processing accuracy are in most cases achieved by using wheels with finer grains. Hardened parts and hard alloys are ground with finer-grained wheels than non-hardened ones. For grinding parts made of materials prone to greater clogging (brass, copper and many others), use wheels with a higher large grain. For large contact surfaces of the grinding wheel with the workpiece (for example, grinding with the end of the wheel), wheels with larger grains are used.

The grain size of a grinding wheel characterizes the cross-sectional size of the wheel grains. The surface cleanliness and processing accuracy depend on the size of the grains; The grain size is determined by sifting abrasive grains through a series of sieves with different numbers of holes.

The grain size of grinding wheels is selected depending on the type of work performed and the requirements for the roughness of the surface being processed.

The grain size of the grinding wheel affects the quality of the sanded surface; The finer the grain of the wheel, the cleaner the surface is. The grain size of grinding wheels is characterized by the size of its abrasive grains and is designated by the corresponding number.

Grinding wheel imbalance class

1A1 250x40x34 24A F30 L 5 V 35 B 3
The imbalance class of a grinding wheel characterizes the imbalance of the wheel mass, which depends on the accuracy of the geometric shape, the uniformity of mixing of the abrasive mass, the quality of pressing and heat treatment of the tool during its manufacturing process. Four classes of permissible imbalance of the mass of circles have been established ( 1 , 2 , 3 , 4 ). Unbalance classes have nothing to do with the accuracy of balancing wheels and flanges before installing them on a cylindrical grinding machine.

Grinding wheels are an abrasive tool used for abrasive grinding of surface layers various materials. Using grinding, you can level out the defective and rough relief that arises as a result machining material. Choosing the right grinding wheel will save you a large number of time and effort to process the material. It is also worth remembering that abrasive grinding wheels differ in their performance characteristics and, if chosen correctly, they can serve for a long period of time.

Classification of grinding wheels

Today on the market you can find a huge number of wheels intended for grinding products made of various materials; they all have design differences and can be used as an attachment for working with special equipment. tools. According to GOST “Grinding wheel: GOST R 52781-2007”, all wheels differ in type and can be:

1. Ring;
2. Disc-shaped;
3. Conical;
4. Double-sided conical;
5. With a conical groove on one or both sides;
6. With recessed center;
7. Special reinforced with a recessed center;
8. With one-sided or two-sided undercut;
9. With a cylindrical recess on one side and a conical recess on the other;
10. With two grooves.

In such a variety, it is easy for a person uninitiated in construction to get lost, and there is no need to know them all, since they usually use a “folk” classification, according to which abrasive grinding wheels are divided into:

1. Petal circles. With their help, it is possible to carry out high-quality surface grinding without leaving any residual burrs on the material. They are assembled according to a fan-shaped principle, when the abrasive material resembling petals is arranged in a cascade one after another. Most often, such wheels are used for grinding metal pipes, if the lamellas overlap each other and have cuts, then such wheels are intended for grinding wooden surfaces.
2. Metal grinding wheels. Used to eliminate defects, deposits and irregularities on metal surfaces, such as weld, For example. Since these wheels are required to withstand a much higher level of frictional loads, great attention is paid to testing their strength.
3. Diamond abrasive grinding wheel. Used for finishing the finished surface of almost any material: from ceramics and optical glass to heavy carbide metals. Despite its high abrasive qualities, diamond is fragile, so grinding should be carried out avoiding impact loads. Also, diamond melts at a temperature of more than 800 degrees Celsius, so when working with it, the main thing is not to overdo it and periodically take breaks to cool the abrasive with a special liquid.
4. Velcro grinding wheels. Thanks to their fabric back surface, they adhere perfectly to the end of the sander. Such wheels do not have high performance characteristics and, due to their small grain size, they are most often used for grinding wooden surfaces, steel sheets, or removing light rust.
5. Abrasive fiber grinding wheels. They are used on angular grinding machines and their areas of application include: processing uneven metal and steel surfaces, removing rust, sanding wood. They are made from special cardboard obtained from compressed cellulose pulp.

For an ordinary user, this information is enough to select the necessary abrasive grinding wheel and successfully cope with everyday tasks; for those who want to know more and accurately select the grinding wheel needed for the job, they should pay attention to the markings of the grinding wheels.

Marking of grinding wheels

Grinding wheels differ from each other in many characteristics and parameters, all of which are taken into account in the marking of the abrasive product. These options include:

• Grinding wheel type
• Circle dimensions
• Abrasive material used
• Hardness level
• Grit size
• Unbalance class
• Accuracy class
• Structure
• Type of bundle

Depending on the manufacturer, the marking may be different, since GOST for circles, depending on their purpose, may also vary. For your convenience, we provide an example of decoding a common grinding wheel marked 30A25SM27KA3, which:

1. 30A - type of abrasive used (white electrocorundum)
2. 25 - grain level equal to 315-250 microns
3. SM27 - characterizes that the abrasive grinding wheel belongs to the average type of softness, with an average structure
4. K - inorganic ceramic binder is used
5. A - circle accuracy class
6. 3 - Level of imbalance

All abrasive grinding wheels are marked according to a similar scheme, with the exception of rare differences that depend on the grinding wheel manufacturer.

Type and size of grinding abrasive wheels

We have already discussed the list and variety of types of grinding wheels in accordance with GOST R 52781-2007 a little higher. As for the dimensions, they are designated according to the sample DxTxH, where D is the total outer diameter of the circle, T is its height and H is inner diameter product holes. When choosing the type of wheel, you first need to pay attention to the type of working tool or manual equipment, as well as on the surface of the material being processed. When choosing the size of a circle, you should consider how much area of ​​the circle will be used and whether all of it will be subject to a uniform load. Small abrasive grinding wheels deteriorate faster than large ones, since on them fewer grains have to remove a larger amount of material in total, while on large wheels the load is more uniform and the grains grind down more slowly. Particular attention should be paid to the choice of the size of the diamond grinding wheel, where the thickness of the coating should not be greater than the thickness of the material being processed, otherwise defects may appear on the edges of the surface of the wheel.

Abrasive material

Diamond, silicon carbide, CBN, and electrocorundum are used as abrasives on grinding wheels. All abrasive materials differ in resistance to thermal loads, wear resistance, fragility, granularity, but their most important characteristic is the degree of hardness. If you are faced with a choice of which abrasive material should be preferred, then you should consider that:

1. Diamond is used for grinding and finishing of both hard and fragile materials(including glass and ceramics), sharpening cutting tools, as well as for fine grinding. The abrasive diamond grinding wheel is very fragile and can easily split from impact, and is easily self-sharpening.
2. Normal electrocorundum is used for processing materials that have high tensile strength. The abrasive has a high viscosity, which makes it possible to use it in operations with different levels of frictional load. It has excellent resistance to high temperatures and adheres well to surfaces, allowing it to sand the material evenly.
3. Electrocorundum is white. It is used for the same operations as normal electrocorundum with the difference that white electrocorundum is much more resistant to wear, high temperature, and also treats the surface better.
4. Silicon carbide. It is used when processing brittle materials that crack under corundum, as well as for grinding viscous surfaces such as rubber, aluminum, copper.
5. Elbor. An abrasive wheel with such an abrasive is the next hardest after a diamond wheel, but is much less fragile and protected from impact. Used for grinding and finishing of difficult-to-process parts.

Grinding wheel grit level

Grinding abrasive wheels also differ in grain size - this is one of the most important parameters on which the quality of the work depends. grinding processing, or more precisely, the grain size affects: the amount of material removed per stroke, grinding speed, and the level of wheel wear. Grains are crystalline elements on the surface of a circle, which are distinguished by width: the larger the width, the larger the surface the circle will remove and therefore the less effort will have to be spent on the work. When choosing the level of grain size, you need to start from how clean the surface being processed should ultimately be, since although with the help of large grains you can achieve quick grinding of the material, the cleanliness of the surface of the material will be questionable. The grit markings of grinding wheels are presented in the table below, which takes into account old and current standards that can be used by modern manufacturers.

Grinding wheels

Sharpening machines are widely used today for sharpening any type of metal and steel tools: from countersinks, axes, knives to drills and chains. Despite the more than hundred-year history of development of this machine and the improvement of technology, the main element of the electric sharpener, which directly affects the efficiency of the machine, is the abrasive grinding wheels. On our website you can find a large list of grinding wheels, some of which are presented in the table:

Restoration of grinding wheels

The grains of the grinding wheel wear out and break down over time, which affects the geometry of the wheel and makes it unusable. In order for them to work again, it is necessary to edit the grinding product. At home, dressing is best done with a tool with a diamond abrasive; at enterprises, the wheel is restored using rolling technology.