Cylindrical grinding wheel. Diamond grinding wheels

What are abrasive wheels - materials of manufacture and technology of application. An abrasive wheel is nothing more than a mechanized grinding stone. It is made from grains of abrasive materials mixed with a binder.

The resulting mass is pressed into the required shape and bonded under pressure at high temperature. To use it, it is enough to have any rotating drive with an electric motor (or other propulsion unit), on the axis of which the disk is attached.

Wide selection and various options applications

Main types of abrasive wheels

Types of abrasive wheels and basic surface treatment methods.

Let's look at the most popular ones:

• cylindrical grinding - surfaces are processed whose cross-section is perpendicular to the plane to the axis of rotation is a circle;
• flat grinding - processing of any flat surfaces;
• centerless grinding - usually used at enterprises involved in processing external and internal surfaces, such as: camshafts, bearing races;
• abrasive wheels are used to cut and cut workpieces;
• abrasive grinding of surfaces (for example, the seat and needle of a diesel injector);
• honing - processing of round surfaces (holes) using special honing heads. Used when processing engine cylinders or
• surfaces of hydraulic pumps;
• polishing wheels - used to give the surface a low roughness and a mirror shine;

Cut-off

Designed for cutting hard materials with little effort. Most often they are used in hand-held angle grinders (grinders), but can also be installed on stationary cutting devices.

They are a flat (up to several millimeters thick) disc made of abrasive material, bonded with a bond and reinforced with reinforcement.

The working edge of the disk scrapes chips from the surface of the material being processed, forming a cut. In this case, the diameter of the disk decreases, and the surface always remains ready for use, i.e. The disc is self-sharpening.

Divided by type of material processed:

• used for cutting pipes, profiles and sheet metal;
• for concrete and reinforced concrete, when cutting grooves in concrete structures;
• working with stone, to give required form blanks made of stone and ceramics;

The variety of sizes is impressive

Grinding wheels

Used for emery. Using such discs you can sharpen tools made without the use of hard alloys, as well as finishing blanks of various shapes.

Cross-sectional grinding wheels come in the following geometric shapes:

1. Straight profile. Used for sharpening knives, axes, external and internal grinding, roughing and cleaning work. Flat grinding can be done.
2. Cone-shaped profile. Not used for sharpening teeth circular saws.
3. Double-sided cone-shaped profile. They are used for finishing the profiles of shavers and cutters, gear wheels, and grinding threads.
4. Straight profile with recess, single or double sided. Used for circular, flat and internal grinding, neck and end processing.
5. Single-sided or double-sided cone-shaped recess. They are used for trimming the end with simultaneous cylindrical grinding, as well as cylindrical grinding of the neck and end.

Cup

Divided into:

1. Cylindrical. Used for flat end grinding and tooth sharpening cutting tool, for example, circular saws.
2. Conical. Used for grinding flat guides and sharpening cutting tool teeth.
3. Disc-shaped. Used for processing and sharpening multi-edge cutting tools and finishing gear teeth.

Conical grinding stones

For household sharpening machines, as a rule, universal straight-profile sanding wheels are used, which can easily be changed to cup wheels if necessary to sharpen circular saw. In general, the main advantage of abrasive wheels is - ample opportunities applications.

note

Having a primitive sharpening machine and a minimal set of sandpapers in your home workshop, you can perform almost any work on sharpening, finishing and polishing products from a wide variety of materials.

Abrasive grinding wheels at correct use require some equipment to secure the surface being processed, or at least guides.

Selecting an abrasive wheel

To choose the right abrasive tool, you need to know the capabilities well. grinding machine– power, operating speed, the possibility of their adjustment. Also, for various types The appropriate type of sandpaper should be selected for the surface to be treated.

IMPORTANT! You cannot use the grinding wheel that is “to hand.” Always check that the sandpaper matches the material being processed.

It is also necessary to know whether cooling and lubrication are required for operation work surface grinding wheel. If the abrasive manufacturer's requirements are not met, the sanding wheel itself can quickly be damaged and the workpiece can be damaged. It is important to choose the correct grit size of the abrasive wheel.

Many people have emery at home - electric machine, equipped with grinding wheels. Most often, something is sharpened or polished using emery. There are a lot of abrasive grinding wheels on sale; in addition to them, it is convenient to use diamond grinding wheels in everyday life. However, for initial processing, for rough processing of metal, it is better to use abrasive wheels. Let's look at the classification of sanding wheels, what they are and where they are used.

White circles - they are made of electrocorundum 25A

The most popular wheels, since they are designed for processing non-hard metals, are perfect for the home. Sharpen knives, axes, scissors, process ordinary steel (corners, etc.) - such a circle will work just fine. Huge selection of sizes and mounting holes:

Marking of electrocorundum 25A, most often has White color. Sometimes manufacturers add a coloring element, as a result of which the circle may be blue or orange color. When turning ordinary metal on such a wheel, a very high-quality sharpening is obtained, since the composition of the wheel itself is soft, the temperature during friction is low, so blue scale does not appear on the metal, and since there is none, the metal retains its properties perfectly.

This primarily applies to knives and other cutting objects, since it is very important not to overheat the metal when sharpening. So a grinding wheel made of electrocorundum - great choice for home.

The sizes of circles are different for different machines. The fit is most often 32 mm - if you buy a wheel for home emery. The most common circle sizes are 125, 150, 175 and 200 mm in diameter, fit 32 mm and thickness 10, 16, 20, 25 mm. As you know, there are abrasives for the home different sizes, that’s why circles are produced in several sizes.

Green circles - made of silicon carbide 64C

Green wheels are intended for processing tool steel and hard alloys (for example, brazing on drill bits for a rotary hammer).

The material is more resistant to abrasion, heat when turning, so if you decide to sharpen with this circle kitchen knife, you will probably ruin the knife, since scale will appear on the blade instantly.

Therefore, such a wheel is used only for turning tools made of tool steel (R6M6, R18, steel with the addition of cobalt, also hard alloys VK8, T5K10, T15K6). Of course, sharpening carbide is also not very convenient; you need to use the finest grain of the wheel, but it is best, of course, to sharpen carbide.

The marking of the circle is 64C, the dimensions are the same as for electrocorundum.

It is worth noting that in addition to small circles for everyday use, they produce grinding wheels large diameter, they are placed on large machines. The fit of such circles is 76 mm, 127 mm and 203 mm.

Diameters 250, 300, 350 and 400 mm. Electrocorundum and silicon carbide.

These are large, heavy and expensive wheels to produce. For example, here I am holding a circle 64c 400*40*127 25CM - photo:

What kind of “grain” is there?

Many who buy grinding wheels for emery do not even know how the grit is marked. I think this point also needs to be covered in more detail.

So, the grinding wheel grain is 8, 12, 16, 25, 40-N.

8 is the smallest, 40 is the largest.

In addition to the numbers, you can also see the letters SM - this means a medium-soft circle, the most common because it is not very expensive and endures quite well. A little less often you can find ST grain on sale - medium-hard, its cost is noticeably higher, however, the abrasion resistance is much higher.

For precise sharpening, of course, it is better to take a fine grain, 12 or 16. Often they buy wheels for sharpening skates from us, these are 150 * 8 * 32 12 CM - a wheel with a diameter of 150 mm, thickness only 8 mm, fit 32 mm, fine grain, allows for sharpening just perfect.

For example, to install an emery wheel on a 150 mm machine, it is best to buy one 150*20*32 25 CM - a standard wheel for emery with a diameter of 150 mm, fit 32 mm, wheel width 20 mm. Grit 25 - medium, suitable for sharpening both small tools (knives, scissors) and large ones - axes. SM - a standard medium-soft circle for household use is also suitable. Such a circle costs about 120 rubles.

Before it becomes a finished product, a metal blank is very often processed using abrasive grinding wheels. This is done in order to ensure a highly smooth surface.

Scope of application of abrasive grinding wheels

Polishing any elements not only makes them more attractive in appearance, but is also often necessary with technical point vision. In everyday life, elements of interior items are often subjected to this process, and in industrial production– parts of various machines, machine tools and other mechanisms.

For moving parts, polishing is extremely important: individual parts must be well fitted and smoothed to minimize friction. It is worth noting that the most different materials– metal, stone, plastic, wood. Abrasive wheels are also actively used in a variety of sharpening machines.

Abrasive wheels can vary in shape as they are used for different purposes. In addition to smoothing the surface metal parts often need cleaning to remove rust. It is almost impossible to implement this task without special circles. Using removable attachments for the grinder, you can make recesses, grooves of varying complexity V various materials, including non-ferrous metals, ornamental stone, concrete walls, soft alloys.

Abrasive wheels are very popular among jewelers, for whom polishing items made of precious metals is the main part of their work. Stone craftsmen who work with ornamental minerals and semi-precious stones also use this tool.

There are special varieties grinding attachments installed on a drill. They are actively used during repair or finishing works(for example, for cleaning the surface of walls before laying tiles or applying plaster compositions). Some grinding wheels are excellent at removing old paint with plumbing, cleaning pipes from corrosion and other similar work.

Types of Grinding Wheels

To properly process a part, it is necessary to determine the type of grinding. This will allow you to choose the right abrasive attachments. The main selection criteria are the material of the workpiece and the nature of the impact on its surface.

Thus, grinding wheels with a straight or annular profile are widely used in everyday life and on small metals, sharpening operations performed by their end surface. These wheels are relevant when working with glass, porcelain, and stone (here you can also use flat attachments with one- or two-sided grooves, which are also convenient when carrying out grinding work).

The most common are conical circles, which can be either double-sided or regular. They can be used for all of the above work for surface treatment of parts with a plane. They can also be used to make holes in almost any material.

For machining many parts optimal options can be called a grinding cup wheel and a wheel with disc attachments (most often they have a solid metal nozzles and diamond sputtering). The cup wheel resembles a straight profile tool with a conical undercut. The main difference is that the end is located at a right angle to the side plane.

The range of abrasive wheels by type of abrasive is quite wide. In addition to the previously mentioned diamond coating, electrocorundum is widely used. Solid nozzles are made using electrocorundum. Most often they do not have a base and a pressed core.

Circles made of silicon carbide are also in demand. The latter are divided into two types: black and green (the nozzles have the corresponding color). Green is more fragile.

CBN is a high-strength abrasive. This material It is based on cubic boron nitride. By operational properties it is not inferior to diamond, while elbor differs more high level heat resistance.

Vulcanite and bakelite grinding wheels

Diamond coating is quite expensive, so it is applied in a very thin layer to a metal base. Abrasive wheels with less strength are formed in a different way. Often, for this purpose, a binder ceramic composition is used, where the main components are materials of inorganic origin (quartz, clay, etc.). Highly ground, these binders are added to the selected abrasive when forming the wheel, providing finished product increased rigidity, but also corresponding fragility.

Bakelite nozzles are in great demand on the market. They owe their name to the main filler – bakelite ( artificial resin). This binding component gives the circle elasticity and a kind of elasticity, but at the same time wear resistance is reduced as a result of weaker fixation of the grains (compared to a rigid ceramic base).

It is important not to forget that a rigid base of high hardness can lead to overheating of the metal being ground and, accordingly, burnout of the surface of the processed element. Bakelite nozzles do not have this drawback. They are much softer, so they heat the metal very little and are capable of self-sharpening when processing a part.

The grinding wheel with vulcanite binder is even softer. Here the main abrasive element is synthetic heat-treated rubber. In other words, vulcanization is used in the production of such grinding attachments, which is reflected in their name. Vulcanite wheels have a higher cost compared to ceramic abrasives. However, despite the increased elasticity, their wear resistance is beyond praise.

Selecting a grinding wheel

The main requirement for an abrasive attachment concerns its hardness. The hardness of the nozzle must be higher than the hardness of the workpiece. At the same time, it is undesirable for these parameters to differ greatly, otherwise the likelihood of overheating of the treated surface increases. One of the most important criteria when selecting an abrasive is its grain size.

Large fractions of ceramic or rubber wheels are not suitable for working with soft materials. Fine grains are only suitable for polishing. Often fine-grained abrasives are applied to cutting discs and disc-shaped metal nozzles. Glossy surface can provide fiber circle. If its nozzle is softer than the workpiece, the processing result will be good, but the wear of the tool will also be very severe.

Grinding the surfaces of parts made of various materials is understood as the main initial operation for removing burrs, nicks remaining after the operation of various metalworking machines, and sharpening knives. In order to ensure high-quality processing, it is necessary to select a grinding wheel with characteristics that correspond to the type and size of the part undergoing this procedure.

General information

An abrasive grinding tool is actually a type of cutting metalworking equipment. The cutting is carried out using a large number of solid particles. There are a lot of types of grinding wheels, some of which are known only to those who have encountered them. For example, in the aircraft and space industries, special tools are used. However, it does the same job as other similar devices.

For various coatings There is a type of grinding wheel. With their help, steel, cast iron products, alloys of non-ferrous metals and forged accessories can be processed. There is special equipment for working with glass, ceramics and brick. The most common abrasive tools currently in use are:

• In circles.
• Heads.
• Cutters or cutters.
• In segments.
• Bar devices.

After processing with such equipment, the remaining roughness is determined by classes A, B and AA. Best quality grinding, designated by the letters AA, is achieved on high-precision machines.

Classification of sanding tools

Graduation 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 specifications" and modern "Grinding wheel: GOST R 52781-007". However, what is contained in them will be difficult to understand for most untrained users.

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

Product quality characteristics

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

A circle with the appropriate indicators is selected for use, which are indicated in the markings on the product itself.

Fixture Grit

This is the most significant characteristic. Its value determines how smoothly the sample will be polished. In addition, the size of wear, productivity, and the thickness of the layer removed per 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 such grain size is reduced. In addition, such devices often cause burns to the part.

The old standard defines the grain size in microns, and is now designated in a new way by the letter F with a number. The higher the digital component, the less grain. All these indicators are summarized in the table of grinding wheel grain size.

Materials for manufacturing

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

Application of binding materials

For a tight arrangement and protection from destruction, special substances are used in grinding wheels. Their quality, variety, and even distribution affect all the characteristics of abrasive tools. And also the presence of these materials shows the ability to self-sharpening crumbled areas of grinding stone. If the binding component does not correspond to the surface being processed, the tool loses its main property, wear increases, grains that have not yet been worked are chipped, and burning and clogging appear.

Organic and inorganic binders can be used as binding elements. The first represent ceramic and silicate materials, the second - bakelite and vulcanite.

The following materials are used in a ceramic bond: refractory clay, quartz and spar. They are strong, durable, with a stable cutting edge. Tools on this basis can be cooled with special emulsions. Circles of small thickness are destroyed by lateral impact. Designated K0, K1, K3 and so on. In their production, silicon carbide or electrocorundum grains are 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 elastic. However, when heated, such a compound floats and the grains fall out. To increase heat resistance, cryolite is added to such a bond. Wetting when grinding with wheels with bakelite bond is prohibited.

A mixture of artificial rubber with sulfur produces a vulcanite binder. Its elasticity is higher than that of bakelite, but its heat resistance is worse. Elasticity allows us to produce thin cutting discs with the designations B, B1, B2.

High-strength metal bonds are made on copper, tin, aluminum and other bases. Used in the manufacture of diamond and CBN grinding wheels.

Hardness indicators

This property describes the ability of the disk to preserve grains under external influence. The lower it is, the faster the destruction of the abrasive occurs. The breakdown of the hardness of grinding wheels for machine tools looks like this:

This parameter is determined by the depth of the sandblasting excavation or a Rockwell hardness tester. Most often used grinding discs average hardness. They are extremely productive and durable. Soft tools are suitable for internal and surface grinding. When turning threads and small-diameter parts, hard circles are needed. As a rule, the harder the workpiece, the softer the abrasive tool needed.

Grinding wheel accuracy

When determining this parameter, existing cracks, cavities and the location of surfaces relative to each other are assessed. The most accurate accessories have minimal inconsistencies and are installed on precision machines high precision processing and high-speed equipment. Marked with the letters AA.

The next most accurate abrasive devices are slightly inferior to the highest quality ones. They are designated by the letter, A. Samples of the lowest accuracy category are one and a half to two times inferior to accessories of class A. They are marked with the letter B and are used for less precise grinding operations.

Abrasive size

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

• The outer diameter of the circle is designated D, its dimensions range from 3 to 1100 millimeters.
• The internal diameter, sizes from 1 to 305 mm, is marked with the letter d.
• Height, or thickness, is h with a value of 0.18-250 millimeters.

Tool instability

This characteristic shows deviations grinding wheel for a sharpener from a resting position - in other words, beating during rotation. In the marking stamp it is indicated next to the accuracy class and has designations from 1 to 4. The unit indicates high quality rigging

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 smaller the coefficient, the denser the circle. A dense surface is designated 1-4, marking 5-7 guarantees an average value. 8-10 is an open structure, and a coefficient of 11 and 12 means a porous type of sandpaper.

Safety at work

Operations involving grinding and cutting equipment have several hazards. This is the rotation of the device, the possibility of destruction of the disk while moving, 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. A right choice equipment will allow you to perform cleaning operations with the maximum level of cleanliness.

2017-07-06

Types of abrasive wheels are distinguished by design differences and are regulated by GOST R 52781-2007 “Grinding wheel”. The document defines the following types of products:

• ring;
• disc-shaped;
• conical;
• conical double-sided;
• with grooves on one or two sides;
• with a recessed central part;
• with cylindrical and conical recesses;
• with two grooves.

Image #1:

Products of certain subtypes are used for different procedures: processing, grinding, tool sharpening. In this case, the main selection criterion is related to the type of workpiece being ground and the nature of the impact on its surface.

Grinding wheels with straight and ring profiles are used in living conditions and on compact machines for processing metal products, sharpening tools, cutting edges. They are also suitable for working with glass, stone, porcelain, and ceramics.

Photo #1:

The most popular are conical-type circles (double-sided and regular). With their help, planes are processed and recesses of various shapes are made.

Photo #2:

Cup-shaped and disc-shaped circles with diamond coating. In addition to diamond abrasive, other materials are actively used for the manufacture of wheels: electrocorundum, silicon carbide, CBN, bakelite. We will tell you more about choosing attachments for cutting tools below.

Application of abrasive wheels

The main area of ​​application of abrasive wheels is cleaning surfaces made of carbon steel, cast iron, plastic, non-ferrous metals, glass, iron. The tool is also used for cutting brick, tile, slate, drywall, and concrete. Products are actively used for cutting grooves and slits different forms and depth.

The circles that are installed on the drill deserve special attention. Such nozzles are used during repair and finishing work to clean walls before laying tiles and applying plaster. Removing paint stains, rust and other coatings is another area where abrasives can be used.

How to choose an abrasive wheel

To select an abrasive wheel, pay attention to its markings. The scope of application of the products is of primary importance. There are nozzles for industrial installations and hand tools. To work in a domestic environment, you will need the second option. We will consider the remaining points related to the choice separately.

Abrasive grain size

The particle size on the canvas varies in the range of 12-4000 microns. It is indicated on the circle in the form of a special marking. The generally accepted encryption system is FEPA. The grain size indicator in the table is indicated by the index F. The lower the numerical value, the larger the particles in size.

There are three main grit sizes:

• large (F16-24);
• medium (F30-60);
• small (F70-220).

Large abrasive particles allow you to cut metal, concrete and other hard elements with maximum speed. However, a fine-grit bit is required to carefully cut edges and grooves.

Circle diameter

The diameter of the circle must match the size of the cutting tool. There are products with a diameter of 80-500 mm on sale. Household machines are produced for circles with diameters of 115, 125, 150, 180 and 230 mm. How larger size products, the easier it is to saw a thick metal part.

Photo #3:

Photo No. 4:

Type of processed material

The best abrasive wheels are those that are suitable for the material being processed. Information about this will be given by drawings on the surface in the form of stone, concrete, ceramics, metal, etc. There are also universal products that are suitable for working with different coatings.

Rotational speed

Pay attention to the estimated rotation speed of the nozzle. It should be slightly higher than the one it works on Grinder. This parameter is indicated by the color of the strip on the product:

• green - 100 m/s;
• red - 80 m/s;
• yellow - 63 m/s.

Circle Density

The choice of abrasive wheel is influenced by its structure (density). This parameter shows how far apart the grains are from each other. The specific type of backfill is selected according to the density of the material being processed. There are three structure options:

• closed - for metals and aggressive grinding;
• semi-open - for non-ferrous metals, paints, plastics;
• open - for wood processing.

Let's give specific examples. Circle PS18EK with filling open type Suitable for wood processing, rust removal, paint, putty. The PS22K semi-open attachment is designed for sanding metal and hardwood. The dense backfill product PS21FK is suitable for machining stainless steel.

Marking of abrasive wheels

The full markings applied to abrasive wheels contain the following information:

• circle type;
• dimensions(height and diameter);
• abrasive material;
• grit class;
• hardness level;
• material structure;
• type of connecting element;
• rotational speed;
• accuracy class.

Circles 125-150 mm are closer to universal ones. They weigh little, yet easily solve a variety of household tasks. Also, when purchasing, check that the diameter of the mounting hole of the circle matches the mount on the grinder. The standard value here is 22 and 32 mm. There are 10 mm holes in circles that are installed on a drill.

Image #2:

Circles are marked according to different editions of GOST standards, so the codes contain differences in hardness, density and other parameters. To understand the markers, review the table below.

Photo No. 5:

1. Abrasive material: 25A - white electrocorundum.
2. Grit size: 60, that is, 800-630 microns.
3. Hardness: K - medium.
4. Structure: 6 - medium.
5. Connecting element: V - ceramics.
6. Unbalance class: 2.

Photo No. 6:

1. Abrasive material: 14A - normal electrocorundum.
2. Grit size: 36-30, that is, 525-625 microns.
3. Hardness: Q-U - medium/hard.
4. Connecting element: BF - bakelite with seal.
5. Unbalance class: 1.

How to calculate the need for abrasive wheels

It remains to understand how to calculate the need for abrasive wheels when processing individual materials to determine the volume of purchases. There is no absolute calculation criterion, since consumption depends on a number of parameters, including the quality, density and hardness of the wheels, as well as their suitability for the selected material.

The following table will help you with your calculations.

Image #4:

In a simplified form, the consumption can be determined in practice. To do this you should:

1. treat a certain amount of surface;
2. divide the footage by the number of nozzles used.

In everyday life, this calculation is sufficient. If we're talking about on production cost control, the data is recorded and a document is drawn up on the rate of abrasive consumption, which is signed by the director of the enterprise.