Round grinding wheels. Types and application of grinding wheels

Diamond grinding wheel is a kind of diamond consumable tool. Used in manual and automatic (including angle grinders) for finishing, sharpening, honing and grinding. It is used for processing hard-to-cut and hard-alloy materials, ceramic surfaces, glass, precious, ornamental and semi-precious stones. It has an optimal balance of strength and brittleness, is characterized by increased efficiency, large working margin and self-sharpening.

Scope of application of diamond grinding tool

Due to the capabilities of the diamond tool, the areas of its use are very wide. The complexity of processing hard alloys is reduced by several times compared to the work of other abrasive materials. Diamond-sharpened tools work more efficiently and last longer. For single-edged parts with a cutting part made of carbide material, such sharpening increases wear resistance by one and a half times, and for multi-edged tools this figure is even higher.

The surface treated with a grinding diamond wheel does not crack, it does not form chips and other defects. This makes it possible to process glass and ceramic products: car glass, mirrors and much more.

This tool is indispensable when grinding glasses for optical instruments, at enterprises producing porcelain, crystal and glassware, when grinding screens. Grinding with diamonds is widely used in medicine for sharpening microtome knives, scalpels and injection needles, for the treatment and prosthetics of teeth in dentistry.

In addition, diamond grinding wheels are also used for dressing wheels made of other materials.

However, in order for the useful properties of diamond wheels to be fully used, and the result of the work to meet expectations, the right choice of product among many varieties is required.

Construction of diamond grinding wheels

The circles are a body on which a layer of diamonds with different structures is deposited. In addition to the diamond elements, the spraying includes a filler and a binder.

All products have different characteristics and differ in:

• the type and shape of the circle;
• case size;
• degree of granularity;
• link type;
• concentration of diamonds;
• unbalance class;
• accuracy class;

In addition, they are characterized by strength, hardness, wear resistance.

Frame

For the manufacture of cases of diamond wheels, steel grades St3, 30, 25 and 20, aluminum alloys of grades D16 and AK6 or polymers are used.

For grinding wheels having the shape of AGC or A1PP, shanks made of steels U8 or U7 are required.

Diamond concentration

The concentration of the diamond layer, which is expressed as a percentage, is the number of grains in 1 cubic millimeter of the powder used in the abrasive layer. This characteristic affects the efficiency and economy of the tool. The concentration is dependent on the grit - the higher the grit and the harder the material to be processed, the greater the percentage of diamond concentration required to work.

Diamond grinding wheels are available in 150, 100, 75, 50 and 25 percent concentrations. 100% is taken as 4.39 carats (1 carat equals 0.2 g) contained in 1 cm3, which corresponds to 0.878 mg/mm³.

This indicator determines the performance, cutting ability, service life and price of the tool. The optimal performance depends on the area and shape of the material being processed, the type of tool used, the quality of the bond, the grain size of the diamond grain and the processing conditions.

The choice of circle concentration is based on the following requirements:

• a high concentration is necessary if the contact surface of the workpiece and the grinding wheel is small (for example, during round grinding), this guarantees a long tool life and increases its wear resistance;
• a low concentration is chosen for the treatment of contact surfaces of a large area.

Grain

Grain is the size of a diamond grain or intergrowths of crystals (this indicator is determined by thickness, width and height, but usually only width is taken into account). The degree of granularity determines the surface cleanliness after processing, work productivity, the amount of material removed per single pass of the circle, tool wear and other indicators.

The granularity is indicated in accordance with GOST 3647-80 and is indicated in microns by a fraction, in which the numerator in microns indicates the size of the upper sieve, and the denominator - the lower one. According to international FEPA standards (and GOST R52381-2005), the characteristic is denoted by the letter F with the corresponding number - the higher it is, the smaller the grain size.

The grain size is selected depending on the required surface roughness after processing, the type of material, the size of the allowance removed during the passage of the tool, etc.

The surface to be treated is cleaner, the smaller the grain size is used. But fine grain is not always preferable - it gives high purity, but at the same time leads to clogging of the tool and burning of the treated surface. Using a fine-grained wheel also reduces productivity.

Grain size varies according to fractions as follows:

• small 100/80;
• average 125/100;
• large 160/125;
• larger 200/160.

Circles with a lower index are used for final finishing of blades, knives, cutters and other products, for final grinding. The middle link allows you to achieve the necessary sharpness of the cutting parts, and coarse grains are used to level and remove part of the machined surface.

It is advisable to use low-grain wheels to reduce surface roughness, and coarser grain when you need to increase productivity and with large allowances. The less viscous and harder the material, the greater the grain size index.

Bonds for diamond grinding wheels

Grinding diamond wheels are produced with three types of bonds: metal, denoted by the letter M (compositions of tin, zinc, copper, aluminum act as the basis), ceramic, denoted by the letter K (with a base of glass or fireclay and the addition of aluminum) and organic, marked with the letters KB or K (from carbolite or pulverbakelite). If a filler is used, then its role is played by a powder of graphite, copper, alumina, electrocorundum or boron carbide.

Diamond wheels in the design of which a metal bond is used are characterized by increased heat resistance and strength, retain their geometric shape for a long time and are distinguished by a long service life, but are quickly clogged. They are used for grinding large volumes of material and its pre-treatment. The result is a surface with the eighth-ninth roughness class. The filler in such circles is not used, and the working layer can be fixed on the transitional steel ring, which is attached to the body.

Properties of wheels with a metal bond:

• high hardness;
• high speed and productivity;
• good indicators of heat resistance and thermal conductivity;
• high cutting performance.

An organic bond requires the use of a filler. It has low hardness, heat resistance and thermal conductivity, but rather high productivity and processing speed.

Wheels with an organic bond are used in finishing and finishing work, for finishing and fine sharpening of products made of superhard materials and hard alloys, in the processing of medical and measuring instruments. Allow to obtain the surface of the eleventh and twelfth roughness classes. Unlike circles with a metal bond, they are little salted, but diamonds are consumed three times more.

Vitrified bonded tools are characterized by a nickel-diamond coating, which can be applied in one or more layers. The thickness of the bond is two-thirds the size of the diamond grains. Due to this, the crystals protrude above the surface of the ligament, but are securely fixed. As a result, the resulting chips are easily removed from the treated area.

Properties of vitrified wheels:

• high cutting ability;
• affordable cost;
• any geometry;
• high thermal conductivity.

Used for grinding and cutting germanium, silicon, sital, other semiconductor materials, technical glass and ceramics, stone processing. It is also used for finishing products made of alloyed steels, hard alloys, in the manufacture of hand tools.

Diamond wheels with a metal bond are operated only with water cooling, with an organic bond they can work both with and without cooling, while the use of alkaline solutions is not allowed.

Grinding wheel hardness

The wheel hardness index does not depend on the hardness of the diamond coating. This characteristic indicates the ability to hold diamond grains in a bond when in contact with the surface to be treated. The hardness depends on the technology used in the manufacture, the shape and grain size of the grain, and the quality of the bond.

The self-sharpening of the wheel depends to a large extent on hardness - its ability to restore cutting characteristics after the removal or destruction of diamond elements. During operation, the cutting grains break and fall out, while new diamonds begin to act, which prevents the appearance of cracks and burns on the treated surface. The possibility of self-sharpening decreases with increasing hardness of the wheel.

Wheels are divided by hardness into 8 groups, designated according to GOST 19202-80 and R 52587-2006 with the following signs:

• VM1, VM2 F, G - very soft;
• H, I, J, M1, M2, M3 - soft;
• K, L, CM1, CM2 - medium soft;
• M, N, C1, C2 - medium;
• O, P, Q, CT1, CT2, CT3 - medium hard;
• R, S, T1, T2 - solid;
• T, U, BT - very hard;
• X, Y, Z, V, W, Th - extremely hard.

The choice of hardness is determined by the shape of the part and the required grinding accuracy, the type of processing, the type of tool used, and the properties of the material. Deviations from the optimal characteristics can lead to the appearance of cracks and burns (if the hardness is higher than necessary) or to a change in the wheel geometry and its wear (if the hardness is insufficient). It is especially important to follow the rules for selecting a wheel for hardness when working with products made of hard alloys.

Increased wheel hardness will be required if high accuracy of dimensions and shapes is required. If cutting fluids are used during operation, the hardness may be higher than when dry grinding.

Accuracy class

The accuracy of the geometric shapes and sizes of diamond wheels corresponds to three classes and is designated as: B, A or AA. Less critical operations are carried out with class B tools, class A refers to better and more accurate. And high-precision circles AA are designed for use on multi-circle and high-precision machines or automatic lines. It corresponds to circles characterized by the uniformity of the grain composition, the accuracy of geometric parameters and the high balance of the diamond composition, in the manufacture of which the best grades of materials are used.

Unbalance class

The unbalance index of the mass of a diamond grinding wheel depends on the uniformity of the abrasive mass, shape accuracy, pressing quality and other parameters acquired during manufacture. Instruments are produced in four classes of unbalance (indicated by numbers from 1 to 4). This indicator does not apply to the accuracy of the balancing assembly.

Types of work: with and without cooling

Water-cooled grinding is preferable because it can apply more severe conditions and cause less wear on the wheel itself. It also reduces the possibility of burns and other thermal damage to the treated surface. As coolants for grinding wheels, not water is used, but 1-5% emulsion.

For wheels with a metal bond, it is recommended to use BV lubricant, a 1.5-3% emulsion obtained from the NGL-205 emulsion, or from the Aqual 10 emulsion. For wheels with an organic binder, a 3% emulsion of industrial oil, soda ash in the form of a 0.5: 1.0% solution, 0.1% wetting agent OP10 or OP7, or an emulsion obtained from borax, sodium nitrate, triethanolamine and trisodium phosphate.

Geometric parameters of circles

Grinding wheels are characterized by dimensions, including: hole and outer diameters, profile height, width of the diamond layer, etc. The geometric parameters of diamond grinding wheels are indicated according to FEPA standards related to tools made from diamond powder. Each item of equipment has its own letter designation:

• outer diameter of the product - D;
• thickness of the base part of the hull - E;
• bore diameter - H;
• support end diameter - J;
• inner groove diameter - K;
• the total length of the bar -L;
• shank length - L1;
• the length of the diamondiferous layer - L2;
• radius - R;
• outer corner of the body cone - S;
• the total height of the circle - T;
• thickness of the working part - T1;
• height of the diamondiferous layer (if T=1 or
• width of the working part of the diamondiferous layer - U1;
• working angle - V;
• layer width - W;
• thickness of the diamondiferous layer - X;
• shank diameter - Y;
• concavity of the working layer - P.

This product is certified according to GOST R 50460-92, and described according to GOST 24747-90.

Types of diamond grinding wheels

Grinding diamond wheels are manufactured in accordance with the requirements of GOST 2424, which includes more than 30 types that differ in geometry. The circle can be of a straight profile, conical, annular, with one- or two-sided undercut, with a one-sided hub, disc-shaped, etc. Each of the main types is designated by its identification number:

Straight profile wheels are made in the form of flat discs with a diamond layer at the end. Are applied to processing of surfaces which demand obtaining the sustained plane.

Cup wheels are made in the shape of a cup and are used for grinding and finishing materials that are difficult to conventionally process: glass, stone, ceramics, hard alloys.

Disk discs (with a small recess) are used in the processing of steel, cast iron, art glass, for removing paint and varnish coatings, sharpening carbide-tipped saws, etc.

Descriptions of some of the more common grinding wheels:

• 14A1(A1PP) - flat cylindrical, with dimensions D 6-13 H 6-10 S 2-4, designed for grinding conical and cylindrical blind and through holes;
• 1A1(APP) - flat straight profile, with dimensions D 16-500, H 2-50, S 2-5, for grinding sharpening and finishing of conical and cylindrical surfaces, carbide parts;
• 6A2(APV) - flat with a recess, with dimensions D 80-300, H 18-32, S 1.5-5, for flat sharpening, grinding and finishing;
• 9A3(APVD) - with a double-sided undercut, with dimensions D 100-250, H 6-25, S 1-5 for finishing, sharpening and grinding the cutting parts of carbide tools;
• 12V5-45(ACC) - cup conical, with dimensions D 50-250, H 20-52, S 1.5-5, for grinding, finishing and sharpening carbide tools;
• 11V9-70(А1ЧК) - cup conical, with dimensions D 50-150, H 20-40, S1.5-5, for grinding in the corners of parts and working with carbide tools, stone and glass;
• 1EE1(A2PP) - with a conical double-sided profile, with dimensions D 125-250, H 6-20, S 2-4, for processing the protrusions of the ends of cylindrical surfaces, grinding grooves and slots;
• 1F6V 1FF6V(A5P) - with a profile of a semicircular-convex shape, with dimensions D 50-150, H 2-32, S 2-7, for grinding round-concave grooves and surfaces;
• 1A1R(AOK) - diamond cutting wheel, with dimensions D 50-400, H 0.5-2.5, S2.5-5, for cutting parts and blanks from ceramics, hardened steels and hard alloys.

How the geometric shapes of various diamond discs look like can be seen in the table:

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

The shape and width of the diamond layer

Each circle has a diamond layer of a certain shape and width. A large width will be required when working "on the pass." Plunge grinding requires a width commensurate with the width of the surface to which the forces will be applied, otherwise ledges appear after processing.

The choice of the section shape also depends on the tasks and the shape of the treated surface. The cross section of the diamond layer is indicated by a specific letter, which can be found in the table:

Grinding wheels also differ in diameter, but the choice of diameter depends both on the tool used, and on the workpiece and the desired result. Also, when working with a diamond grinding tool, it is required to take into account the number of spindle revolutions on a particular equipment.

Marking of diamond grinding wheels

Diamond wheel 12А2-45 (АЧК) 150x20x5x32 AC4 160/125 B2-01 100%

With the correct selection of the circle and compliance with the requirements for a particular type of work, such a tool will significantly increase the speed of execution and productivity of work, save money, and the tool itself will remain operational for a long time.

In most cases, to give the final product a smooth surface, metal blanks are processed using special grinding wheels. Thanks to polishing, it is possible to achieve the external attractiveness of the element, as well as supplying it with the technical characteristics necessary in a particular situation.

This tool is widely used both in the processing of interior items and for fitting, for example, bar and panel parts of industrial production. Giving smoothness to moving parts is especially important., since ensuring that their friction is minimized plays a big role in the operation of all equipment.

Grinding can be subjected to a fairly wide range of materials. These include stone, metal, plastic, and even wood. Removable nozzles allow you to form various grooves and recesses in non-ferrous metals, concrete walls, soft alloys, which are brought to the final version by cutter heads.

Often, grinding wheels are used not only to smooth metal surfaces, but also to remove rust deposits from parts, which is almost impossible to do without this equipment. In many cases, craftsmen purchase abrasive wheels for grinding machines, with which other cutting tools are also quickly used.

This product has earned particular popularity among jewelers, who are mainly engaged in polishing precious metals. The tool is also often used for surface treatment of semi-precious stones and ornamental minerals.

On the market you can find special varieties of grinding nozzles that are installed on a drill. They are used in the process of repair work, for example, when cleaning walls for the subsequent laying of tiles. Certain types of circles allow, when installed on an electric sharpener, to clean pipes from corrosion, remove old paint from plumbing, and so on.

Types of equipment

To carry out the correct processing of parts, it is necessary to determine the type of grinding. Thanks to this, you can choose the best option for the abrasive nozzle.

To the main selection criteria for this equipment include the following components:

• the material from which the workpiece is made;
• the nature of the work performed on the surface of the product.

Grinding wheels equipped with an annular or straight profile are often used to work on small emery and machine tools, in everyday life, as well as for sharpening carried out by the end surface of the tool. Stone, porcelain and glass are used as materials with which this equipment works.

The most popular can be called ordinary and double-sided conical circles, the work of which is based on the surface treatment of the part with a plane. They also allow for recesses in a wide range of materials.

Often, experienced craftsmen have in their arsenal cup circles and tools with disc-shaped all-metal nozzles equipped with diamond coating. The cup modification resembles straight profile equipment with a conical undercut. It differs only in the rectangular arrangement of the butt in relation to the lateral plane.

If we consider the types of equipment depending on the type of abrasive, we can distinguish a fairly wide range of tools. In addition to the diamond spraying indicated above, which is usually used for sharpening and finishing hard-alloy elements, electrocorundum is considered quite popular, which makes it possible to produce solid nozzles. Corundum wheels are usually made without a pressed core and base.

An abrasive called elbor has a special strength. The basis of this material includes cubic boron nitride, which is practically not inferior to diamond in its operational characteristics. Moreover, it has an undeniable advantage, namely: a high level of heat resistance.

The technique for performing diamond spraying on abrasive nozzles does not involve the use of any binding elements, since it is applied to the metal in a thin layer. This is the reason for the significant high cost of such equipment. Abrasive wheels with less strength are made using a ceramic binder composition, which usually includes materials of inorganic origin, such as clay, quartz, etc. They are carefully crushed and added to the selected abrasive during the formation of the wheel. Due to this, the final product becomes rigid.

There are two main types of nozzles depending on the binder in the abrasive:

• bakelite;
• volcanic.

The most popular are bakelite nozzles, which include artificial resin in their composition, which gives the circle the necessary elasticity and elasticity. However, the indicated component also causes a decrease in wear resistance, which occurs due to insufficient grain bonding. This is not observed in circles on a hard ceramic base. However, it is worth remembering that hard bases with high hardness can provoke overheating of the metal being ground, and this is fraught with overburning of the surface of the workpiece. There is no such drawback in Bakelite nozzles. They are quite soft, slightly heat the metal and self-sharpen during operation.

Even greater softness have circles with a volcanic component. They use heat-treated synthetic rubber as an abrasive element. In the production process of the equipment, the vulcanization method is used, which formed the basis of the product name. Such circles are somewhat more expensive than modifications equipped with ceramic abrasive. But this is not surprising, because in addition to excellent elasticity, they also have increased wear resistance.

Features of choosing a tool

The main criterion for choosing a grinding stone is its hardness. This indicator should not be less than the hardness of the part being processed. Moreover, it is not permissible to allow large differences in such parameters, which is fraught with a possible overheating of the surface.

An important criterion during the election of an abrasive can also be called granularity. Usually, to establish the optimal grain size, it is necessary to familiarize yourself with the requirements for the purity of the processing of the final product. Each grinding wheel is equipped with its own marking, the decoding of which allows you to choose the right emery tool. It is usually represented by the type of abrasive material, the degree of unbalance, size and type, structure, degree of hardness, level of accuracy, grit, nature of the bond and maximum processing speed.

To work with metal and wood, it is necessary to use grinding wheels of different grits, otherwise the quality of the finish may be poor. If notches or rough strokes are detected on the surface of the processed element, it can be confidently stated that the choice of the grain size of the equipment was made incorrectly.

For the convenience of using the tool, a table of grit size of grinding wheels has been created, which allows you to quickly understand the necessary parameters and decide on the choice of nozzle.

The most popular types of such tools include grinding wheels with the following designations:

• with a grain size of 120;
• grit 60;
• with 100 grit.

Depending on the specific type of operation being performed, the master selects the necessary type of equipment. For rough grinding, wheels with large grain fractions are usually used, and for finishing, this figure should be much lower. In addition, when selecting a tool, the features of the grinding equipment mode and the technical properties of the cutting element are taken into account.

When working with soft materials, rubber and ceramic circles with large fractions should not be used. Fine-grained nozzles are used only for polishing. Usually abrasives with small grains are applied to disc-shaped metal nozzles, as well as to cutting discs. To ensure a glossy surface, it is logical to use a fiber circle. In this case, the processing result will be better when choosing a tool with a softer tip than the material of the part being manipulated. However, this is also often accompanied by rapid tool wear.

When working with large surfaces, you should opt for large diameter grinding wheels. Such a recommendation will save equipment, because a small element will need to rotate much more often, which will lead to its rapid deterioration.

Having approached the choice of a grinding wheel thoroughly, you can find a tool that will prove itself in the work as efficiently as possible at the lowest financial cost.

If a certain amount of material remains on the workpiece, then it can be removed from the surface of the part using grinding wheels. Sharpening is performed in the same way, and any notches are smoothed out.

All grinding wheels differ both in appearance and in the method of manufacture. However, this tool of any brand, regardless of size, is able to improve the technical and operational properties of the product.

In addition, after grinding, the appearance of the treated surface is improved. For example, decorative mirrors, crystal chandeliers and porcelain tableware are processed with small-sized grinders, as a result of which the products acquire a silky smoothness.

In some cases, specialists use a grinding tool of a non-standard configuration. Specific grit and circle shape are used for particularly complex professional tasks. For example, for a complete set of machines on productions.

Types of grinding wheels

The classification of grinding wheels is determined by GOST R 52781–2007.

It stands for:

• material of manufacture;
• scope;
• technical requirements.

However, the main value is the operating conditions.

Grinding wheel shapes

Both among professionals and in domestic use, classification according to the options for using circles is popular.

According to the purpose and features of use, the following types of grinding wheels are distinguished:

• Self-locking. Fastening method - Velcro. Differ in strong coupling with the grinding machine.
• Petal. Flap-type grinding wheels are characterized by the complete absence of secondary burrs. They perfectly adapt during use to any surface due to the fan orientation of the petals.
• Fiber. Requires a support plate of a given section for engagement with the grinder. Used for cleaning any materials (from wood to steel).
• Diamond. Used for finishing material.
• Metal discs. They are subject to thorough analysis (testing) for strength, as they are required for the final work with the seam after welding.

Ligaments: varieties and classification

Types of bonding of grinding wheels are determined by the area of ​​use. Experts divide them into organic and inorganic.

Types of grinding wheels by types of bonds:

• Bakelite. Required for finishing. Suitable for sharpening and flat grinding. The bond is characterized by a high polishing effect, but it is not resistant to aggressive chemical environments.
• Ceramic. One of the most fire resistant This type of tool is characterized by the highest chemical resistance, as well as the ability to maintain an edge profile. However, the bond has a low coefficient of resistance to mechanical stress. In particular, it must be protected from bending loads.
• Magnesian and silicate. They are particularly sensitive to coolants. They are endowed with a low coefficient of strength, but they emit less heat during operation.
• Volcanic. Needed to work with particularly complex curly surfaces, as well as for profile grinding. It has rubber and sulfur in its structure, so the scope is very specific. The structure of these grinding wheels is very dense, which provokes increased heat transfer during the grinding process. Without periodic breaks in work, it softens, and the cutting process becomes not so high quality. With strict observance of technological standards of operation, it guarantees a perfectly flat surface, therefore it is used for finishing grinding curly surfaces with complex geometry.
• Metal. Required for grinding especially hard alloys.

pivot table

It is from the type of bond of grinding wheels that the hardness of the tool and its strength depend.

Wheels for grinder

Everyone who has come into close contact with grinding or cutting knows what grinding wheels are for grinders.

On the market they are presented in a wide variety:

• abrasive circles. Designed for grinding work and fast cutting.
• Diamond coated discs. The tool is relevant for construction work. Without difficulty, not only stone or concrete, but also metal are divided into fragments. There are solid and segmented options on the market.
• Saw discs. Similar to a saw, but a more powerful alloy is used in their manufacturing process. The most demanded disk from this series from tungsten carbide.

All types of grinding wheels for grinders have a standard diameter. For example, the smallest model has a size of 115 mm. For private use, 125 mm discs are most widely used.

It should be remembered that marking when choosing discs for a grinder is of great importance. This tool has great power and speed. The slightest discrepancy between the selection of the emery disc and the size of the installed shaft can provoke traumatic situations. Only the right selection of equipment will ensure the effective performance of the required task.

Abrasive grinding is one of the main types of rough grinding, which is performed to reduce surface roughness, dressing, and eliminate periodic relief that occurs on a part after machining on machine tools. The laboriousness of the final readiness of the product depends on the correct choice of the grinding wheel, and its ability to better withstand the frictional loads that arise.

Types and technological application of grinding wheels

Abrasive grinding by rotation is carried out using:

1. circles;
2. heads;
3. cutters (cones);
4. segments.

The quality after grinding depends on the grade of the grinding wheel. There are three of them: A, B and AA. Class B grinding wheels have the least accuracy, and AA wheels have the highest accuracy (they are usually equipped with precision grinding machines). The accuracy of the grinding wheel is determined by its geometry, the composition of the abrasive material on the wheel, as well as the grain size.

In the practice of grinding or dressing on machine tools and manual machines, one-time fastening of the composition to the base is often used. In fact, this is sanding paper with a velcro backing. Such "circles" with Velcro are used mainly in everyday life, for manual machines, moreover, with a slight removal of metal, in particular, when editing.

On the contrary, when removing a significant amount of metal, home craftsmen often use cutters - nozzles for a conventional electric drill that look like a cutter. The cone, rotating at high speed, performs rough grinding of surfaces after drilling or milling. Rollers are compact and have a small working surface diameter. Cone cutters, however, cannot provide much torque.

Standard notation

Marking is determined by GOST 2424, and includes the following varieties:

• for operations of rough (rough) grinding of metal, internal or external, dressing mainly by the periphery - circles with a straight profile (pp);
• for processing threads, and other periodic profiles on metal - double-sided conical (2p), or dish-shaped (t);
• for sharpening and dressing friction cut-off saws - conical one-sided (3p);
• for centerless grinding of metal - circles with one- or two-sided undercuts (pv);
• for face grinding with a flat surface - ring (k).

The above nomenclature refers to solid circles that perform the operation with their entire working perimeter (editing, rough grinding). When using typesetting grinding wheels, special segments are used, which are installed in the corresponding seats of the wheel body on a machine or machine. They are produced in accordance with the technical requirements of GOST 2464. Type-setting segments can process hard-to-reach surfaces (for example, rail cavities, narrow grooves in metal or stone). Grinding segments are more economical when dressing, and make routine maintenance of the machine easier.

Applied abrasive compositions

The initial requirements according to GOST are resistance to frictional wear (moreover, under the combined action of high pressures and sliding speeds), low thermal conductivity and increased surface hardness.

Depending on the intensity of application, GOST 28818 allows the use of the following materials:

1. Electrocorundum on a bauxite component, which is based on high-percentage aluminum oxide Al 2 O 3 with the addition of calcium oxide. This chemical compound is characterized by increased hardness, which is also maintained at high temperatures that occur in the grinding or dressing zone. Marking circles of electrocorundum - from 12A ... 15A for normal, up to 22A ... 25A - for white. With an increase in the index, the strength of the wheel increases due to an increase in the hardness of the base substance.
2. Electrocorundum on a carbide basis. More often it contains carbides of chromium, titanium, zirconium and silicon. Marking starts from 38A (for zirconium) and ends with 95A (for chromium and titanium). The carbides of these metals have an increased resistance to shear shear stresses, and therefore are suitable for removing surface layers of parts that have undergone heat treatment, or for straightening them. The presence of silicon carbide (marking 52C ... 65C) increases resistance to temperature changes.
3. Spherocorundum is a material that is obtained by blowing molten aluminum oxide, resulting in the final spherical shape of grains (in electrocorundum, grains are predominantly flat). The marking of this composition is ES, and it has an extremely high hardness. This circumstance makes it possible to use spherocorundum for grinding materials with increased hardness, including even hard alloys.
4. Monocorundum (marking - 43A ... 45A), where the grinding grain, unlike other types, has a single-crystal structure. This increases the durability of the abrasive composition, but at the same time increases its cost, since the technology for growing single crystals is very complex. A more accessible variety is aggregated monocorundum, in which poly- and single-crystal sections are combined in a certain way.

The degree of granularity is set according to GOST 3647, and is also noted in the marking.

The bonding of the abrasive component with the base is carried out using rings, flanges, glass mesh discs, etc.

The role of ligaments

In addition to the cutting agent itself, the manner in which it forms the abrasive mass is also important. GOST allows the use of Bakelite or ceramics as binders. The bakelite version is good for its higher density, so the wheel has an increased mass, suitable for metal work, but with a limited circumferential speed (especially if a hand grinder is used). The use of ceramics makes the grinding wheel lighter, and the permissible speed of its rotation on the machine increases accordingly. However, the abrasive resistance as well as the hardness of the ceramic wheel are reduced.

The ligament also determines the method of attachment to the body base. For example, film bonding is suitable for vitrified bonds, but not for Bakelite bonds.

A special type of ligament is a fiber. Such a base is used in the so-called "cold" grinding of metal on a machine or machine, when the surface of stainless steel or the weld zone is cleaned. At the same time, the material being processed practically does not heat up, since the depth of the grinding zone is insignificant (the process is actually closer to polishing). Marking is carried out in accordance with GOST R 51967.

Other types of ligaments are also used to a limited extent - from various epoxy compositions, magnesite, porcelain.

How to choose the right size and type of tool

The choice depends on the processing conditions, the main equipment used (machine or manual machine), as well as on the material being ground.

The manufacturer also matters. Among consumers, there is a slang designation of the instrument - "Luga" and "Volga" circles. In the first case, the manufacturer is OAO Luga Abrasive Plant, and in the second case, OAO Volzhsky Abrasive Plant.

The Luga plant produces products in accordance with GOST based on silicon carbide, and imported components are used as feedstock. The products of the Luga plant on ceramic and bakelite bonds made of white electrocorundum are also popular. Circles of the Luzhsky plant with a steel bottom - a novelty of the manufacturer - can significantly increase the tool life during centerless grinding.

The products of the Luga plant are used for both round and flat grinding. The Luga circle is suitable for both a machine tool and a manual machine.

The Volzhsky plant manufactures circles in accordance with GOST from silicon carbide (wastes from metallurgical and refractory production are used). In the products of the Volzhsky plant, semi-finished products are used with strict compliance with the classification of European manufacturers of abrasives FERA. The goods of the Volzhsky plant were among the hundreds of the best domestic goods.

When choosing a domestic manufacturer - Volga or Luga - they are guided by the following practical recommendations:

• the goods of the Luga plant show the best resistance when grinding on machines or machines of products made of cast iron, aluminum, copper alloys, most non-metals;
• the products of the Volzhsky plant are more popular in situations where, in addition to the actual grinding, editing is also necessary. The products of the Volzhsky plant are also used for steel work.

Buying the optimal circle according to GOST of one standard size (Volga or Luga) is an unrealistic task in most situations. When using a manual machine, you need a wheel that can withstand the maximum number of revolutions, and when working on a stationary machine, you need a tool that is able to withstand higher pressures.

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

Purpose of grinding wheels

The scope of these processing tools is wide. They differ not only in appearance, but also in the way they are made. With the help of grinding wheels, you can remove a small volume from the surface of the workpiece, thereby improving the technical and operational characteristics, and appearance.

A variety of 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, most often used end, which are installed on a drill. In addition, the marking of the product, the possibility of using it on special grinding machines, and the size should be taken into account.

Ways to use grinding wheels, depending on the marking and composition:

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

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

Some types of work sometimes require grinding wheels of non-standard configurations and sizes. In other models, they differ not only in grain size, but also in shape. Most often, such models are used to complete factory machines.

Types of grinding wheels

To determine the types of grinding wheels, you must familiarize yourself with GOST 2424-83. It indicates the destination area, the material of manufacture and the requirements for the technical parameters of this type of tool. But the operating conditions are decisive.

Currently, the following types of end and flat wheels with the appropriate marking and designation can be used to perform grinding work:

• grinding for metal. Are applied to processing of welded connections. After installation on the drill, the end part is used to process workpieces and parts;
• diamond. Designed for final grinding of the surface of the workpiece. It should be remembered that they belong to the category of grinding. Characterized by a special composition;
• fiber. Made from multilayer vulcanized paper. Processing takes place both with the end and planar part 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 types of workpiece surfaces. With the help of flap discs, rust is effectively removed;
• self-locking. Characterized by a high grain size. One part has an adhesive base for installation on a drill. Designed for fine processing of wooden or metal surfaces.

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

The diameter is also taken into account. For household machines, models with a diameter of 50 to 300 mm are used. Specially shaped wheels can be set during fine processing.

Material for the manufacture of grinding wheels

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

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

The structure and composition of the material of manufacture can be determined by marking and designation. The scope of the grinding wheel is also indicated there:

• electrocorundum. They are divided into white (22A, 23A, 24A, 25A), normal (12A, 13A, 14A, 15A, 16A), chromium (32A, 33A, 34A), titanium (37A) and zirconium (38A). The higher the number, the higher the quality of workmanship;
• silicon carbide. It is produced in green (62C, 63C, 64C) and black (52C, 53C, 54C, 55C) colors. The first has a more fragile structure. Used as sharpeners;
• diamond. The main area of ​​application is sharpening and grinding of carbide tools. With the help of diamond wheels, it is possible to finish other types of grinding surfaces;
• elbor. Its properties are similar to diamond, but it is more heat resistant. For domestic needs, it is practically not used as a sharpener, as it has a high cost.

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

In each case, the material of manufacture of the grinding wheel for face machining with a drill is determined on an individual basis. This is influenced by the properties of the workpiece, the required degree of its grinding.

Marking of basic grinding wheels

In order to choose the optimal models of the grinding wheel, you need to know the symbols on its surface. Thus, 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, it is necessary to determine the material of manufacture and the possibility of using it as a sharpener on the machine. Data can be taken from the list described above. Then the graininess of the circle for the drill is recognized. In some cases, the icon indicates that face machining is not possible. Most often this applies to corundum discs for metal.

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

• F, G. Belong to the category of very soft;
• H, I, J. Soft, designed for finishing parts;
• K, L. Thus, products with medium softness are marked;
• M, N. Medium, the most common type;
• O, P, Q. Medium hard;
• R, S. Solid;
• T, U. Very hard, used as a grindstone;
• V, W, X, Y, Z. Extremely hard.

Manufacturers rarely indicate the structure and composition of the disc on the label. First of all, it refers to the type of connection. This term indicates which composition was used to create a homogeneous mass. Currently, ceramic, bakelite and volcanic binders can be used as a binder.

During operation, the geometry of the oval circle or the size of the petal base may be disturbed. In particular, this applies to the end processing of parts with a drill or machine. In this case, it is necessary to make an edit according to the marking. To do this, it is recommended to use carbide tools or diamond blades.

The video shows the main types of grinding wheels: