Types of abrasive wheels. Types of grinding wheels and decoding of their marking Grinding wheels for metal processing

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

Grinding wheel shapes

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

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

All grinding wheels consist of two main components - these are the grinding grains, which actually cut and the bond that holds and holds them together during the cutting process. The ratio of grain to free space andthe ligaments in the wheel characterize the structure of the grinding wheel.

The 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. Sometimes white - 22A, 23A, 24A, 25A(the larger the number, the higher the quality) and normal -12A, 13A, 14A, 15A, 16A; chromic - 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
WA white aluminum oxide + special bond
WAR white aluminum oxide + red bond
WAY white aluminum oxide + yellow bond
PA pink aluminum oxide
RA ruby alumina
DA white and brown aluminum oxide
SA semi-brittle aluminum oxide
HA monocrystalline aluminum oxide
WITH black silicon carbide

Zirconia alumina - this abrasive is used for grinding during rough grinding, indicated 38A or Z.
Silicon carbide - this abrasive is used for grinding gray and bleached cast iron, soft bronze, brass and aluminum and non-metallic materials, denoted64S-62S or GC.

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

The grain size is the number of linearly spaced holes per inch of the screen used for the final screening of the 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 of 30 before 60 (F 56-24)
Small from 80 before 180 (F 24-12)
Very small from 220 before 600 (F 10-4)

Grinding wheel hardness

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 degree if the bonding of the abrasive grains of the grinding wheel is very strong, and it well keeps the grains from being pulled out by the cutting forces during grinding. Conversely, the bond is soft if a small force is applied to pull the grains out of the circle.
Hard wheels are used for work with a small contact area. Soft grinding wheels are used for quick and coarse material removal and for working on hard materials.

Grinding wheel structure

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

The structure of the 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 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 self-sharpening process of the grains.
The choice of the type of bond of the grinding wheel affects the processing speed, its type and accuracy.

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

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

Bakelite bond mainly consists of artificial resin - bakelite. The marking of circles with Bakelite has a Latin letter in the designation ( B). Old designation - ( B). In comparison with ceramic, circles with a bakelite bond have greater elasticity and elasticity, they heat up the processed metal less, but they have lower chemical and temperature resistance.

Bakelite bond can be with reinforcing elements ( Bf, the old designation is BOO), with graphite filler ( B4, the old designation is B4).

Volcanic bond is a vulcanized synthetic rubber. The abrasive wheel marking has the letter ( R). Old designation - ( V)

Grinding wheel accuracy class

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

Dimensional and geometrical accuracy of abrasive tools is determined by three classes AA, A and B... For less critical operations of abrasive processing, a tool of the class B... More accurate and better quality is the instrument of the class A... To work in automatic lines, on high-precision and multi-circular machines, high-precision tools are used AA... It is distinguished by a 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 the surface, for example, the finer the grain of the wheel, the higher the surface roughness class.
The grain 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 the purity and accuracy of processing. In the rough grinding operation, wheels made from larger grains are used than in the finishing one. High requirements for the surface finish and machining accuracy are in most cases ensured by the use of wheels with a finer grain. Hardened parts and carbide alloys are ground with finer-grained wheels than non-hardened ones. For grinding parts made of materials prone to more salting (brass, copper and many others), wheels with a larger grain are used. For large contact surfaces of the grinding wheel with the workpiece (for example, grinding with the end face of the wheel), wheels with a larger grain are used.

The grain size of the grinding wheel characterizes the grain size of the wheel in diameter. The surface finish and processing accuracy depend on the size of the grains; the grain size is determined by sieving the abrasive grains through a series of sieves with different numbers of holes.

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

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

Grinding wheel imbalance class

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

- goods for stone processing.

Grinding disc - one of the types of abrasive tools, along with heads, segments, bars, abrasive belts and abrasives, is actively used for processing various types of surfaces. Abrasives used for the manufacture of grinding wheels are strong, high-hardness substances: diamond, corundum, quartz, as well as artificial materials - electrocorundum, synthetic diamonds, silicon carbide and boron and others. The grains of these substances are machined on the surface of other materials; in terms of their purpose, they can be compared with the teeth of a conventional saw, but located not along the edges, but along the perimeter of the disk. Grinding wheels are used to process many materials: carbon steel, glass, plastic, bronze, wrought iron and non-ferrous metals. In addition, they are used in tools for cutting brick, stone, ceramic tiles, drywall.

A non-professional classification, familiar to many, divides grinding wheels into the following types:

• Discs with the so-called "Velcro" - a special fabric that is applied to abrasive paper.
• Flap circles - have a surface made of abrasive material, located in the form of a fan overlay of layers. They are very durable, provide a smooth surface after processing, and are most often used for grinding pipes or wood surfaces.
• Fiber discs made of vulcanized paper with a multi-layer structure. They are attached to the machine using a support plate with the required section. Fiber discs are used for cleaning metal, wood, steel products.
• Diamond wheels used for finishing. As a rule, they have little strength.

Grinding wheel markings

The quality characteristics of abrasive wheels are regulated by GOSTs, standards and specifications. Each of the grinding wheels has its own marking according to the following characteristics:

1. Grinding material
2. Disk size
3. Grain size
4. Disc type
5. Hardness
6. Binder
7. Instability class
8. Structure
9. Segments
10. Optimum rotation speed

To decipher these points, it is necessary to consider the marking of grinding wheels in more detail.

Grinding Abrasive Type

The most common marking of abrasive wheels by type of material is the following:

• Electrocorundum

Marking 12A, 13A, 14A, 15A, 16A: normal electrocorundum (material with high heat resistance, good adhesion to the binder, mechanically strong grains). It is used for processing wrought iron, cast iron, steel, bronze, chrome-plated steel.

22A, 23A, 24A, 25A: white fused alumina (more uniform than type 14A, harder, with sharp edges, self-sharpening, provides a more uniform surface of the material being processed). It is used for sharpening and grinding tool steel, thin-walled parts and tools, as well as finishing and finishing.

Abrasive wheel marking

32A, 33A, 34A: chromium electrocorundum.

37A: titanium fused alumina.

38A: zirconia. The higher the marking, the higher the strength of the discs.

• Silicon carbide

Marking 52-55С: black silicon carbide (has increased hardness in comparison with the previous type of abrasive, and brittleness). They are used for polishing cast iron, granite, porcelain, silicon, ceramic, glass surfaces, as well as viscous aluminum, copper, rubber materials, heat-resistant steel products.

Marking 62C, 63C, 64C: green silicon carbide. Differs from black in greater fragility.

• Elbor

Marked CBN, CBN, Cubonite, Borazon: Has the strength of a diamond but is more heat resistant.

• Diamond

Diamond wheel marking: AC2 (normal strength), AC4 (increased strength), AC6 (high strength), AC32 (single crystals), AC50, ARB1, ARK4, ARS3. They have the highest wear resistance, strength, and low brittleness. The use of diamond wheels is found in the processing of brittle and high-hardness alloys (cast iron, ceramics, silicon, optical glass), as well as finishing grinding, cutting, sharpening of carbide tools.

Grinding wheels, grit (markings)

A characteristic such as grain size determines the smoothness of the processed surface. The grain size of the grinding disc determines its wear rate, the thickness of the removed metal layer in one pass, etc. The smaller the value of one grain, the smoother and cleaner the surface will be.

The grain size determines the marking of the discs:

• Grinding grain: the size of the fraction is from No. 200 to No. 16
• Grinding powder: No. 12-4
• Microsection powder: М63-М14
• Fine micro-grinding powder: M10-M5.

The grain size units are given in microns. The marking of diamond grinding wheels, more precisely, the type of their grain size, is indicated in a different way (through the fraction of the upper and lower values).

Circle size

The dimensions of the discs are regulated by GOST 2424-75. Marking D is a numerical designation of the outer diameter, d is the inner diameter, h is the height (width). The outer diameter can vary from 3-1100 mm, the inner diameter is from 1.0 to 305 mm, and the height is from 0.18 mm to 250 mm.

Instability class (imbalance)

There is a designation of four classes of imbalance (from 1 to 4), i.e. admissible values ​​of the disc deviation from the static balance. The imbalance class refers to the ratio of the mass of the abrasive disc to the accuracy of its geometric shape. Therefore, imbalance and accuracy markings are often indicated side by side. Accuracy class A is used to work on high-precision equipment, class B is more versatile, AA - discs of ideal shape and geometry made of very high quality abrasive.

Structure

The density of the structure is indicated depending on the ratio of the number of abrasive grains to the volume of the disc. The more abrasive per unit volume of the grinding wheel, the denser its structure. If the tool is sharpened, a disc with a less dense structure is more susceptible to cleaning the surface from material particles, creates less risk for deformation, and cools faster.

The numerical designation of the structure is as follows:

1,2,3,4 - dense structure;

5,6,7 - medium density;

8,9,10 - open;

11.12 - porous.

Grinding wheel markings: old and new, the difference is according to GOST

Conventional disc indicators until 2008 were regulated in accordance with GOST 2424-83. A new version of GOST 2424 entered into force in 2008. In 2009, the marking of abrasive wheels began in a new way: modern standards for the symbolic designation of the hardness of the processing tool (GOST 52587-2006 instead of the old GOST 18118, 19202, 21323), grain size ( GOST 52381-2005 instead of GOST 3647-80), bundles (new GOST 52588-2006).

Also, modern indicators of the types of grinding wheels differ from those adopted in the USSR. The existing designation of grinding wheels is as follows (the previously used designation is indicated in brackets):

• - a section of a circle of a straight profile (PP). Suitable for universal use

5 - straight profile with one-sided groove (PV). It is used for cylindrical grinding.

7 - with two undercuts (LDPE)

10 - with hub and double-sided groove

• - ring type (K)

6 - cylindrical cup-shaped (CC). Used for sharpening tools.
36 - with fasteners (PN)

11 - conical cup shape (CC)

41 - cut-off disc type

4 - with a conical profile of double-sided type (2P)

• - type with conical profile (3P)

12.14 - plate-shaped (T, 1T).

Flap discs are marked with the type, outer diameter, inner diameter, height, grain size and sanding paper series.

Bond type marking

The bond holds the grinding grains together with the backing and with each other. Usually, three types of bond markings are indicated on discs: volcanic, ceramic and bakelite.

The first type of ligament is denoted as R, or the obsolete designation is "B". It consists of a vulcanized synthetic rubber.

The ceramic bond is marked as V, the former name is "K". It includes a combination of inorganic substances (clay, quartz). Its advantages are wear resistance, thermal and chemical resistance, but at the same time fragility.

The bakelite bond is marked as B, previously known as "B4" and "BU". It contains artificial resins. This is an elastic bond, but otherwise the parameters are lower than that of a ceramic bond.

Hardness indicators

The hardness index of the grinding wheel indicates the strength of retention of the grains by the bond on the surface when the abrasive being processed is applied to the disc.

The hardness designations of the disk start from very soft (BM1, BM2) to extremely hard (HR), in the new designation, the marking is carried out with letters of the English alphabet, starting with F (very soft) to Z (extremely hard).

Most often, discs of medium hardness are used, but the choice of the type of degree depends on the type of work performed, the surface of the material, and the tool itself.

Grain

According to the previously valid GOST, the marking of the degree of granularity was expressed in measuring the number of grains in a volume of 10 microns; for micro-grinding powder, these values ​​were expressed by adding the letter "M". The new standard establishes the designation with the letter "F" with the addition of a number that indicates the degree of grain. The larger it is, the less grain and vice versa.

Grinding the surfaces of parts made of all kinds of materials is understood as the main initial operation for removing scoring, chipping remaining after the work of various metalworking machines, sharpening knives. For the purpose of high-quality processing, it is necessary to choose a grinding wheel with characteristics that correspond to the type and size of the part undergoing this procedure.

General information

The abrasive grinding tool is actually a kind of metal cutting equipment. The cut is carried out using a large number of hard particles. There are a lot of types of grinding wheels, some of which are known only to those who have come across them. For example, in the aircraft industry and the space industry, a special tool is used. However, it does the same job as other similar devices.

Different coatings have their own type of grinding wheel. With their help, steel, cast iron products, non-ferrous metal alloys and forged accessories can be processed. There is special equipment for working with glass, ceramics and bricks. The most common abrasive tools in use today are:

• In circles.
• Heads.
• Milling cutters, or cones.
• Segments.
• Bar devices.

After processing with such equipment, the remaining roughness is determined by classes A, B and AA. The best quality AA is achieved on precision machines.

Classification of sanding tools

The grading of circles by type occurs in two ways. The first of them is determined by two official documents: the old Soviet GOST 2424-83 "Grinding wheels: technical conditions" and the modern "Grinding wheel: GOST R 52781-007". However, what is contained in them, most untrained users will have little understanding.

For this, there is a second, popular specification of the grinding tool:

Quality characteristics of products

There are a lot of different parameters by which such products are classified. There are even more types of abrasive wheel markings due to the fact that there are many different combinations of these properties. The main parameters of abrasive wheels for grinding machines are considered:

For use, a circle is selected with the corresponding indicators, which are indicated in the marking on the product itself.

The grit size of the fixture

This is the most significant characteristic. Its value determines how smoothly the sample will be ground. In addition, the size of wear, productivity, the thickness of the removed layer in one cycle also largely depend on this indicator. The smaller the grain of the tool, the higher the cleanliness of the processing. However, the speed of work with this grain size is reduced. In addition, such a device often causes a burn on the part.

The old standard defines the grain size in microns, in a new way it is denoted by the letter F with a number. The higher the digital content, the less graininess. All these indicators are summarized in the table of grinding wheel grit sizes.

Materials for making

Like all characteristics, the requirements for the material from which the grinding wheels are made correspond to GOST. Minimum conditions are wear resistance, low heat transfer, solid surface. Based on these conditions, an abrasive tool is made from the following material:

Application of bonding materials

For a dense arrangement and protection from destruction, special substances are used in the grinding wheels. Their quality, variety, even distribution affect all the characteristics of abrasive tools. And also the presence of these materials shows the ability to independently sharpen the crumbled sections of the grinding stone. If the binder component does not correspond to the surface to be treated, the tool loses its main property, wear increases, chipping of grain that has not yet been worked out, sticking and salting appear.

Organic and inorganic binders can be used as binding elements. The former are ceramic and silicate materials, the latter are bakelite and vulcanite.

In a bunch of ceramics, the following materials are involved: refractory clay, quartz and spar. They are strong, durable, with edge stability. Tools on this basis can be cooled with special emulsions. Circles of small thickness are destroyed by lateral impact. K0, K1, K3 and so on are designated. In their manufacture, silicon carbide or electrocorundum grain is used. They grind well in all ways, except for cutting and use in narrow grooves.

Powder from bakelite resin and varnish makes up a bunch of B, B1, B2 and others. Such circles are thin, strong and resilient. However, when heated, such a compound floats and the grains fall out. To increase the thermal stability, cryolite is added to such a binder. Do not wet when grinding with Bakelite-bonded wheels.

A mixture of synthetic rubber with sulfur gives a vulcanic bond. Its elasticity is higher than that of Bakelite, but its heat resistance is worse. Elasticity allows the production of thin cutting discs with the designation B, B1, B2.

High-strength metal bond is made on copper, tin, aluminum and other bases. It is used in the manufacture of diamond and CBN grinding wheels.

Hardness indicators

This property describes the disk's ability to preserve grains when exposed to external influences. The lower it is, the faster the destruction of the abrasive occurs. The decoding of the hardness of grinding wheels for machine tools looks like this:

This parameter is determined by the depth of the excavation from the sandblast or a Rockwell hardness tester. The most commonly used grinding discs are medium hardness. They are as productive and durable as possible. For internal and surface grinding, soft tools are suitable. When turning threads, small-diameter parts need hard wheels. Generally, the harder the workpiece, the softer the abrasive tool is needed.

Grinding wheel precision

When determining this parameter, the existing cracks, cavities and the location of surfaces relative to each other are evaluated. The most accurate accessories are characterized by minimal discrepancies and are installed on high precision precision machines and high speed equipment. Marked with the letters AA.

The next abrasive tools in terms of accuracy are slightly inferior to the highest quality ones. Designated by the letter, A. Samples of the lowest accuracy category are one and a half to two times inferior to accessories, A - class. They are marked with the letter B and are used for not the most precise grinding operations.

Abrasive tool size

This parameter is observed in accordance with GOST 2424-75. The dimensions of the discs are strictly observed. All grinding equipment is designed according to these standards:

• The outer diameter of the circle is denoted D, its dimensions are from 3 to 1100 millimeters.
• The inner diameter, with dimensions from 1 to 305 mm, is marked with the letter d.
• Height, or thickness, is h with a value of 0, 18-250 millimeters.

Instrument instability

This characteristic shows the deviation of the grinding wheel for the sharpener from the rest position - in other words, the runout during rotation. In the marking stamp it is indicated next to the accuracy class and has designations from 1 to 4. The unit indicates the high quality of the tooling.

Surface structure

Its density is determined by the ratio of the number of grains to the volume of the disk. Accordingly, the greater their number and the lower the coefficient, the denser the circle. The dense surface is designated 1-4, the 5-7 marking guarantees the average. 8-10 is an open structure, and a factor of 11 and 12 indicates a porous type of emery.

Work safety

Operations with equipment performing grinding and cutting work have several hazards. This is the rotation of the device, the possibility of destruction of the disc on the move, the threat of touching rotating equipment. To maintain health, you need to fulfill the following requirements:

Modern grinding tools and machines greatly facilitate human work. Choosing the right tooling will allow you to perform stripping operations with the highest level of cleanliness.

Removing a layer of material from a part or workpiece by abrasive action with a tool is one of the main processes in metalworking. It is produced on special machines and using electric or pneumatic tools, while the main working element is grinding wheel... In this case, the possibility of parts of a particular configuration depends on the type of grinding wheel, the shape of its cutting surface.

The main types of grinding wheels

The types of abrasive wheels used in industry differ in design features and are regulated by GOST R 52781-2007. The document contains 39 types of circle profiles, but if we take the most frequently used ones, then the following types of tools can be distinguished, which have:

• straight profile;
• ring profile;
• conical profile;
• conical double-sided profile;
• undercuts on one or two sides;
• a profile with a recessed front part;
• conical and cylindrical grooves;
• two undercuts.

You can learn more about the profiles of abrasive wheels in the video below.

Each of the above types of grinding wheels is maximally adapted to carry out certain operations - processing, grinding, polishing, sharpening. The main selection criterion is the type of workpiece to be processed and the nature of the processing. In addition to smoothing the surface, they are used to prepare grooves, grooves of various configurations and other operations with ferrous and non-ferrous metals, concrete, stone and other materials.

So, abrasive wheels type 1 with a straight profile in accordance with GOST R 52781-2007 are widely used for grinding operations. In this case, the main working surface is the butt end of the circle. They are also widely used for external, internal and centerless circular grinding, as well as flat grinding with the periphery of the wheel.

For similar operations, abrasive wheels of type 2 with an annular profile are also used, which differ from type one in a larger width of the end part. This allows you to significantly increase the processing area when carrying out circular external, internal and centerless grinding, as well as when sharpening.

Discs with tapered and double-sided tapered profile can be used for all of the above works. Due to its shape, this type of wheel can be used for various recesses. It is also used for grinding gear teeth and threading.

Cylindrical and conical cup circles are widely used for sharpening tools. They are also great for flat face grinding. In their configuration, they resemble circles with a straight profile and a tapered undercut, but differ in the location of the end at right angles to the lateral plane.

Another commonly used type of grinding surface is disc discs. Due to their configuration and the minimum size of the end face, they have been used in the processes of sharpening and finishing the front edges of cutters, processing teeth of slotting and other tools.

How to choose an abrasive wheel

In addition to the above types of abrasive wheels, other factors must be taken into account when choosing a tool. First of all, this is a field of application, industrial machines or hand tools. Next, you should decide on the grain size of the tool.

The particle size of the circle can be from 12 to 4000 microns, which is indicated by the index F in the marking. Coarse-grained wheels are considered to be F16– F24, medium-grained - F30– F60 and fine-grained - F70– F220. The larger the grain size, the faster the removal of layers of metal and other materials, but the poorer the surface quality. Therefore, fine-grained wheels are used for final, precise grinding.

The best option is for the circle to match the material being processed. This can be judged by the images on the surface (metal, stone, concrete, etc.). There are also universal ones, suitable for any surface. Also pay attention to the permissible rotation speed indicated on the product label and additionally indicated by the color of the marking - green up to 100 m / s, red - up to 80 m / s and yellow up to 63 m / s. Only with the right choice of the shape and characteristics of the circle can you ensure high quality and safety of work.