Carbon brushes spark on an angle grinder: how to solve the problem

All types of cutting machines with electric motors have a brush assembly. This is a bracket with carbon-graphite coins fixed on it, which are pressed against the collector rings. Through these elements, electric current flows to the rotor windings.

An electromagnetic field appears, due to which the angle grinder shaft begins to rotate. It turns the gears of the gearbox, and through them - the cutting or grinding wheels.

After using the grinder for a long time, sparks may begin to fly out of the brush assembly. This indicates that the carbon-graphite nickels are very worn out.

It is typical that the contact of their surfaces with the collector plane deteriorates. In this case, the power of the electric motor will drop significantly. You can feel this: if you press hard on the grinding wheel while cleaning parts, the electric motor of the angle grinder will stop rotating. If the wear of the brushes is critical, the grinder will not work.

Why the brushes on the grinder burn?

Why do the BRUSHES on the GRINDER SPARKLE and blaze so quickly? Let’s look at the prerequisites and solutions. Strong sparking often indicates imminent tool failure. It is necessary to understand in time the causes of excessive spark formation and take measures to eliminate it.

Prerequisites for sparking of electric motor brushes. Wear of brushes. If these parts are heavily worn, the electric motor does not develop speed at full power, and may also not turn on (all the time or occasionally). In this case, when the electrical appliance is turned on, you can use a screwdriver with an insulated handle to press the brush against the armature. If an increase in engine speed is observed, then the problem has been correctly identified. Most likely, replacing worn parts with new ones will correct the situation. From time to time it is also necessary to replace the brush holder springs. Interturn closure of the armature winding. A malfunction of devices with electronic engines may be a broken armature. In this case, sparking will be observed in the area of ​​​​both brushes, and the armature winding will get very hot due to the fact that some contacts receive a larger current than others.

HOMEMADE from GRINDER.

My channel: https://www.YouTube.com/c/DmitriiIzumov VK.com: https://vk.com/id197936402

Play.Lists: ① ⚒ all videos ⚒ https://www.YouTube.com/playlist?list…

Optimization. DO NOT read: grinder repair, stator replacement, grinder repair, bearing replacement, rotor, grinder repair, brush replacement, comfortable grinder , how to choose a comfortable grinder, whole rotor, whole stator, new brushes, why the grinder . commutator, deformation, sparks, intermittent operation, twitches, increased sparking, uneven wear of the commutator, grinder sparks, how to fix, how to check the stator, how to check the armature, diagnostics of power tools, inter-turn short circuit, how to determine whether it is the armature or the stator, what the grinder is out of order, definitions of interturn short circuit, interturn short circuit indicator, why the brushes are on, short circuit indicator, grinder gets very hot, little known breakdown, angle grinder sparks, brush tunnel, grinder broke, grinder , angle grinder, angle grinder , replacement, brushes, why, doesn’t it turn on, heat up, work, how, with your own hands, make, brushes,

“Bulgarian9” itself has nothing to do with it. This phenomenon applies to all commutator-type engines. Motors of the so-called serial type are installed on hand-held power tools. This is when the stator windings are not connected in series. This is because initially the myth was that the type of electric motors was created for direct current. However, the use of a sequential circuit allows it to be connected to an alternating current circuit. The speed of such a motor is not limited by the frequency of the current, as is the case in brushless electric machines. Due to the increased speed, a number of requirements are imposed on the commutator assembly, which are aimed at reducing sparking under the brushes, without thereby reducing engine heating. And so, the spark is increased if:

Something like this. Choose from this list that doesn't just suit your situation.

Why in Bulgarian

Do the brushes burn out quickly (I installed new ones and they burned out in three minutes)?

Let me argue a little with the previous answers. That's it, under no circumstances should you install copper-graphite brushes. They are denser and do not cause mechanical damage to the anchor. Which then leads to a possible short circuit of its winding, and this turns the contact surface into something similar to sandpaper, this again gives rapid wear for simple graphite brushes.

Copper-graphite brushes are mounted only when the contact surface of the armature has a special coating or is made of a special alloy.

READ How to Make a Circular Angle From a Grinder

There is another option for the reason for rapid wear of brushes - armature beating. Edelweiss is a matter of wear on the bearings of the electric motor bushings, depending on what is installed. However, this is a rarer case.

And as another possibility, it is worth mentioning the possible presence of a micro breakdown in the winding. Heating occurs in the electric motor just at the right time, this heating does not manifest itself as a micro breakdown, something like this happens. only very weak, the brushes begin to burn out quickly.

The best option would be to take the grinder to a workshop. There they would check it - if desired, they would grind the contact surface, ring the winding, replace the bearings or bushings. If you can’t do this, then you can at least try to grind the anchor yourself. Disassemble the engine, clamp the armature into a drill at maximum speed and polish it. You just need to use sandpaper of the smallest grit, micron. Not here, practically do not put any effort on it, but only lightly touch it. And then carry out the second stage - initially rubbing the sandpaper against each other, thereby erasing the surface layer and such a situation will already be like polishing. And the final step is to polish it with a piece of cloth, also called felt, moistened with machine oil. Don’t forget that the layer to be removed must be minimal - a micron or two, based on the existing damage.

Here you need to make a precise determination - are your brushes burnt out or worn out?

If they burnt out, then I have never seen anything like this before; when the motor shorts out, the brushes themselves do not burn, since they are made of a material that, by and large, has no right to burn out, unless it is subjected to a large current, alas, then it will be a bunch of sparks no short circuit at the bottom. Which, as far as I understand, did not happen for you.

Therefore, I assume that rapid wear has occurred. Then, of course, we’re not talking about brush wear, but wear on the motor commutator. I've encountered this many times. When, due to commutator wear, the brushes are not worn out first.

What's happening is that the collector itself is divided into parts, look at

To determine the wear of the collector, you will have to get to it without checking the coating.

So I’ll answer it myself, since I figured out what the reason , it turns out I added problems to myself! Like an office worker, when the brushes on the angle grinder wore out and the machine started to work jerkily, it was necessary to stop immediately. alas, for the reason that I had nothing to finish cutting with, I still cut it further. The worn-out brushes hung on the limiters and did not create a huge arc in a circle, alas, the machine continued to spin the disk, it was not I who sawed, the arc ate ​​out a groove on the armature commutator like electric welding, and when I installed new brushes they did not have a plane of pressure against the armature commutator, they did not burn out, they just idled very quickly work. Having disassembled the grinder, I saw a gloomy situation, an attempt to polish the armature commutator at the turner did not end in success, I had to buy a new anchor, since it was impossible to replace only the commutator, and besides, honestly no one even wanted to take on this. The result was that the finished 40X40 profile resulted in the purchase of a new anchor, but that’s not the whole reason for this action.

What spare parts for angle grinders can be changed independently, and how to properly maintain power tools

A grinder at home is like a telephone connection. When the oil is in good working order, no one remembers about it. Once a breakdown occurs, it immediately becomes obvious that you can’t do without it for a day. Repairing this useful electrical appliance on your own is possible even for a novice craftsman.

First of all, let's look at the structure of the grinder.

An internal moving component of an engine. Usually it is integral with the working shaft, through which rotational energy is transmitted to the gearbox.

Armature switching board. The operating voltage from the brushes is supplied through its contacts.

Contact elements pressed against the commutator plates.

The outer winding of the motor, inside which the armature is required to rotate. Located along the inner contour of the instrument body.

A mechanical component that reduces the speed on the working shaft while simultaneously increasing it.

Why do the brushes burn in an angle grinder?

The attached figure clearly shows the electrical circuit and arrangement of the electric motor components.

Tool motor picture

The angle grinder engine operates in extreme conditions. Despite the protection, dust gets inside, most often in the form of small metal filings. Metal is known to be a conductor. When it gets into the contact zone between the brushes and the commutator, microcircuits occur and the copper plates become very hot. Melting and mechanical connection of the collector contacts may occur.

Type of electric motor commutator to be repaired

In this case, the brushes overheat and the working surface burns out intensely. Hence sparks and increased wear. Another reason why brushes spark is when fine sand and wood dust get inside. When the commutator is contaminated with sawdust, the contact between the brushes and the commutator is broken, and sparking occurs under intense load, with all the ensuing consequences. Therefore, for prevention, it is necessary to periodically disassemble the body of the angle grinder and clean the dust from the collector.

It is necessary to periodically blow out the engine of the angle grinder

This simple procedure will extend the life of both the brushes and the armature commutator. It is advisable to at least vacuum the angle grinder after each dusty job, especially in the area of ​​the ventilation holes.

Types of devices for collecting current

Underestimating the importance of the good condition of this part leads to serious consequences. Timely measures to prevent them will extend the service life of the tool.

First you need to understand the types of current collectors:

• The production of graphite brushes for an angle grinder occurs by mixing the base substance with a binder composition. As a result of pressing carbon materials under pressure and further firing, a product with additional strength and wear resistance is obtained. Then the graphitization process begins, which consists of heating to a temperature of 2500-2600 degrees in special furnaces. This is the most common type of such products, although it is quite expensive, but its service life partly compensates for it.
• To produce carbon brushes for grinders, the same graphite or carbon black is used, only additional hardening is excluded from the cycle. This significantly reduces both the cost of the product and its durability.
• The raw materials for the manufacture of metal-graphite brushes, as the name suggests, include metal in addition to the main element. Usually this is copper powder, but the addition of tin, lead or silver is not excluded. metal component can reach up to 80 percent. Applications for such parts are primarily in industrial generators and electric motors. For household needs, these products are too expensive.

READ Disc For Grinder Cutting Wood

Before purchasing a replacement set of brushes, you need to find out their type and dimensions in the technical data sheet of the tool.

Why do brushes burn out quickly?

What are the reasons for the rapid burning of brushes on a tool?

Diagnostics of the electrical part of an angle grinder

As mentioned above, most often an angle grinder refuses to work due to breakdowns of the electrical part of the unit. To correctly diagnose the electrical circuits of a tool, electrical equipment repair technicians use a special device - a tester.

If you press the start button of the unit and it does not work, then in 90% of cases the cause of the breakdown is not so serious that you cannot repair the angle grinder yourself.

The first step is to check the electrical cable and the plug at its end. If it is collapsible, then unscrew it and check the reliability of the contacts. Otherwise, you will have to disassemble the angle grinder (remove the casing of the device) and “ring” the cable with a tester, and also make sure that the current is suitable for the contacts of the “Start” button. If the device shows a break, the cable should be replaced with a new one.

The situation when current flows to the button, but does not pass further (when in the on position), indicates a malfunction of the switch. The button cannot be repaired. It needs to be replaced with a new one, but first mark the contacts you are removing so that you can connect them correctly in the future. If the contacts are connected incorrectly, the motor winding may burn out.

If during the check it turns out that both the cable and the start button are in good condition, but no current is supplied to the brushes, then it is necessary to clean the contact plates of the brush holders. If this procedure is ineffective, it is recommended to replace the brushes. Next, if everything is fine with the brushes and current is flowing to them, you should check the rotor and stator for shorts and breaks.

Checking the motor armature

The electric motor rotor may have the following malfunctions: interturn short circuit and broken conductors at the lamella contacts. You can check the armature of an angle grinder with a multimeter: the device is switched to the resistance change mode, the value is set to 200 Ohms, and the resistance between two adjacent lamellas is measured using probes. Thus, it is necessary to check all pairs of lamellas. If the resistance values ​​are the same, then the rotor winding is not damaged. Detection of other resistance values ​​during “ringing”, as well as detection of an open circuit, indicates a malfunction in this coil. In this case, the angle grinder's anchor will need to be repaired.

If you do not have a measuring device, you can check the rotor using a 12 V light bulb and a battery for this purpose. The power should be between 30-40 W. The test is done as follows: apply 12 V voltage from the battery to the plug of the angle grinder, connect a light bulb to the gap in one wire, and start rotating the angle grinder spindle. If the winding is in good condition, the light will burn evenly, without blinking. With an interturn short circuit, the degree of incandescence of the light bulb filament will change. In this case, repairing the angle grinder's anchor with your own hands will be difficult, since the armature winding scheme is quite complex, and the process itself requires special equipment and knowledge. Therefore, it is recommended to entrust this operation to specialists. But the best way out of the situation would be to replace the anchor on the angle grinder with a new one.

If the light does not light up when testing the rotor, this indicates a break in the stator or a short circuit in its windings, as well as problems with the electric brushes.

Checking the motor stator

To check the stator of the angle grinder, use a multimeter, as in the previous case. The values ​​need to be set to 20-200 Ohms and do the following. Touch one probe to the contact of the stator winding, and the second to the body of the part. If the device shows resistance, this means that a breakdown has occurred to the housing. Touch the probes to the contacts of one winding, and then to the contacts of the other. If the resistance is the same, then the coils are working. If the device shows an open circuit on one winding, it means that the stator will need to be rewinded or the part replaced with a new one.

Rewinding the stator at home without special knowledge, skills and equipment will be problematic. It is better to contact specialists who professionally rewind motors.

What is this?

These components are made by mixing the carbon black substance with graphite and other binding components - hardeners. This mixture is a good conductor of electric current.

Rectangular brushes are widely used. They may differ in length and width depending on the specific electrical appliance in which they are installed.

A copper wire without winding is mounted in the “body” of each brush, to the free edge of which a plate of an individual configuration is soldered. The wire is located inside a spring, which rests against the brush with one edge and against this plate with the other. The spring exerts a free pressing action, and the brush fits tightly against the commutator as it rotates.

During operation, the brushes wear out due to constant friction. This creates the need for their planned replacement. For this purpose, the manufacturer supplies the power tool with a spare set of brushes.

In other situations, you can observe the appearance of sparks in the area where the brushes are located. This fact is accompanied by a characteristic sparking sound and the smell of burnt graphite. If the brushes on an angle grinder spark, this is a sign of a malfunction of its components. In this case, you need to diagnose the device.

Peculiarities

Electricity is supplied to the armature windings of the electric motor using a commutator unit. During operation of the apparatus, the armature rotates, contact appears, the number of revolutions is quite large, this leads to strong friction. The brushes form a “sliding” contact that converts mechanics into electrical energy. Their main task is to remove and supply current to the collectors. Electric current is also removed from the slip rings. The main thing is that the brushes are installed correctly. The kit includes tips with wires aimed at a high-quality fastening mechanism of the bolts located on the brushes.

There are different types:

• graphite – aimed at simple switching, consisting of graphite;
• carbon-graphite - characterized by weak strength, they are often used on equipment with minimal loads;
• electro-graphite – are high-strength, withstand medium contact conditions;
• copper-graphite - have good strength, have strong protection that protects against gases, as well as various liquids.

There are also improved models of brushes in a plastic case. In appearance, they are no different from the above, only they have protection in the form of a housing or a plastic shell.

Causes

There may be several reasons why the brushes on an angle grinder spark and wear out a lot:

• malfunction or increased wear of the brushes themselves;
• violation of the contact density between them and the collector plates;
• deterioration of the pressing action of the brush spring;
• breakdown between the collector lamellas;
• axial runout of the armature due to bearing wear;
• short circuit in the armature winding;
• introducing structural damage to the mechanism during repairs.

The reasons listed above are a consequence of improper operation of the angle grinder or poor assembly of its components.

In order to avoid the appearance of sparks in the area of ​​the brushes, you should follow the rules for the safe use of angle grinders.

• Do not turn on if there is high humidity, significant voltage drops in the network, dirt gets into the brush block, or contamination of the air grilles in the housing.
• Avoid overheating the engine or the load that slows down the rotation of the mechanism during operation.
• Do not use a low-power grinder for sawing “heavy” materials.

What are they made from?

Brushes for grinders and other power tools are made from different materials, but the main ones are coal and graphite. This material has a low coefficient of friction and also has increased abrasion resistance. To improve contact, various impurities are added to the composition of graphite or carbon during the manufacture of brushes. Depending on the impurities used, the following types of brushes are distinguished:

• Coal
• Copper plated
• Carbon-graphite
• Graphite
• Copper-coal
• Copper-graphite

The composition of the main part affects not only the service life or wear, but also such a parameter as signs of sparking. The amount of brush sparking depends on the composition from which they are made

When purchasing them, you need to pay attention to the composition, and not purchase equipment of unknown origin and questionable quality.

This is interesting! The design of the brushes contains a ceramic tip, which performs one of the important tasks. When the graphite layer is abraded to the limit, the tip begins to contact the copper lamellas of the commutator. Ceramics do not conduct electricity, so when the brushes wear out, the grinder will work intermittently or will not turn on at all until the devices are replaced.

Grooving with sandpaper

The armature shaft is fixed in the chuck of some torque mechanism (lathe, drill). The rotation starts and the abrasive is applied to the commutator. Avoid forceful pressure and the use of coarse sandpaper. The minimum grain size is 1000 P.

Using a multimeter, detect the presence of a breakdown in the armature winding. Set resistance test mode. Place one probe on the lamella and the other on the contact of the corresponding winding route. The absence of an open circuit will be indicated by an audible signal. If there is no signal, this route is broken. You will need to replace the armature or rewind its winding.

Determine whether there is any runout in the bearings. If it is found, replace the bearings and measure with a micrometer the diameter of the edges of the armature shaft in the places where it adjoins the assemblies.

Removing the chuck: Bosch screwdriver

Bosch brand screwdrivers are usually equipped with a fixing screw.

• We place the key in the cams and tighten it a couple of clicks.
• The tool is placed on the edge of the table.
• By pressing the stop button, remove the cartridge lock on the shaft.
• The cartridge is removed counterclockwise.

All actions require special attention and consistency during disassembly/assembly.

Having acquired theoretical knowledge about the types of cartridges, it will be easier for you to independently repair screwdrivers from Interskol, Hitachi, and other manufacturers.

The essence of the problem

Sparking brushes prevent the power tool from operating at full capacity. Since they are the connecting link in the electrical circuit, disruption of their operation leads to interruptions in the current supply. This negatively affects the motor winding and reduces its operating life.

Sometimes the fault may lie in the brushes themselves. They quickly burn out due to cracks, chips, scratches, and overheating. Replacing the old brush set will solve the problem. If the reason for the sparking is not the brushes, then the new ones burn the same way.

How to repair an angle grinder with your own hands

Unfortunately, the entire instrument fails sooner or later, but this is not a problem - it can be repaired. Now I will tell you how to repair an angle grinder with your own hands.

The first step is to remember in detail the circumstances under which the breakdown occurred. For what? This will help determine by 50% what exactly is broken or burned in the instrument. It’s one thing if a concrete slab fell on the grinder, and quite another when, during operation, all the light bulbs flashed brightly and then burned out. Is the difference obvious?

The electrical part can burn out from overload (hence, overheating) of the tool during operation, from a surge in supply voltage, from ingress of conductive liquids, due to long-term storage in a damp room, pulling the plug by the power cord, pressing the switch too suddenly and forcefully, etc. P.

Mechanics do not like abnormal operating conditions, lack of proper lubrication of bearings and gears of the gearbox, abrasive dust and moisture getting inside, falling on the floor during operation, and lack of regular maintenance.

Before you start repairing an angle grinder, you need to thoroughly clean its body with your own hands - they love it, and sometimes they immediately start working. If this does not help, then you will have to disassemble the machine. Unscrew the mounting screws and remove the casing.

Repair of electrical parts of angle grinders

The electrician is to blame when the grinder is completely silent, or slowly turns the shaft and (or) strongly sparks the brushes. There may be a smell of burnt insulation.

In 90% of cases of “malfunction” of a power tool, to fix it, you just need to plug the plug into a known-good socket. If everything is fine with the outlet, then first of all you need to check the power cord and the power button in sequence.

A malfunction in the engine speed control circuit can be checked by passing current around it using a short piece of wire. Please note that at this moment the motor rotates at maximum speed, so first of all, make sure that it is designed for mains voltage (220 volts).

The most common malfunctions in which you can still repair the angle grinder yourself are breaks or short-circuited turns in the armature and/or stator windings. They usually arise due to overload and overheating of the tool.

The problems of armatures and stators are divided into:

• winding fault,
• damage to the magnetic circuit,
• damage to the armature commutator.

The simplest, but very effective diagnosis of their malfunction is a thorough external examination, which in most cases is sufficient to decide on the possibility of further operation of the engine spare part or the type of repair.

If inspection fails to find the problem area, then the following instruments are used: probe, ohmmeter, LATR, inductor with cut “iron”. For advanced repairmen, the PUNS-5 device is produced.

Watch a video about diagnosing a malfunction when trying to repair an angle grinder yourself.

Technique for troubleshooting an electric motor using LATR

By slowly increasing the voltage at the LATR output to 250V, we determine the nature of the fault in the armature and stator windings.

• Increasing proportional to the increase in voltage, sparking across the entire surface of the brushes is most often an interturn short circuit.
• At low voltage, the armature tries to rotate in different directions (in different positions) - probably an interturn short circuit.
• A narrow spark on the brushes, increasing in proportion to the increase in voltage, indicates a very high probability of a wire break or poor contact with the commutator.

As the voltage increases, the spark on one brush increases abruptly—a breakdown of the wire insulation in the stator winding.

The presence of too large sparks on the commutator may indicate poor balancing of the rotor (armature) - as the voltage increases, the engine noise should gradually increase, and there should be no vibration. If at some point resonance appears, it means the balancing is poor.

Method for troubleshooting an electric motor using an ohmmeter

The resistance between adjacent contacts of the collector is checked - it should be equal for each measurement, or across one contact (armatures are sometimes specially wound this way to reduce losses on odd harmonics).

The resistance between the magnetic circuit iron and the collector contacts must exceed several megohms (the absence of breakdown to the housing is checked).

Sources:

https://servis-prof.ru/faq/pochemu-bystro-stirayutsya-shhetki-na-bolgarke.html https://schemy.ru/info/pochemu-bystro-stirajutsja-shhetki-na-bolgarke/ https:/ /i-perf.ru/bolgarka/pochemu-iskryat-cshetki-v-bolgarke.html

Malfunctions of grinder brushes and their elimination

An angle grinder is a high-speed electric tool equipped with a commutator electric motor. In this motor, current is supplied to the armature - the internal rotating part. This feeding is carried out using a sliding method, and the only way to make contact between the power source and the moving part is through graphite “brushes”. They are “fuses” against voltage overload and are the first to fail.

A sign of their obvious malfunction is strong sparking with the emission of sparks through the ventilation grilles, accompanied by a characteristic sound.

Background

The electric angle grinder was invented in the first half of the last, twentieth century. Serial production began in 1954 by the German company FLEX-Elektrowerkzeuge.

In our country, people over 40 remember what CMEA is. It was according to the plan of the Council for Mutual Economic Assistance in the 1970s in Bulgaria, then a country of people's democracy, in the city of Lovech that the production of angle grinders began under the Eltos brand. A significant part of the plant's products was supplied to the USSR.

The first Eltos, dubbed “grinders” by the Soviet people, had a sensational success in various industries and construction, and made it possible to mechanize and speed up many technological processes associated with the processing of sheet and profile metal. Due to the low number of revolutions, the previously used straight grinders had only one function - grinding, and low mobility, since they were powered from a three-phase electrical network.

Modern grinders, which work wherever there is a 220 V outlet, owe their global distribution to German engineers who managed to turn a DC commutator electric machine into a small-sized, high-speed single-phase UKD, a universal commutator motor.

Briefly about the design of the engine. The electromotive force (EMF) arising in the windings forces the rotor with the armature placed on it to rotate in the electromagnetic field of the stator, while consuming a considerable current, measured in tens of amperes. How are these amperes transferred from the windings of a stationary stator to the rapidly rotating rotor?

This difficult problem is solved by a brush-collector unit.

The engine brush is a modest part that performs important functions in extreme conditions.

Note. Do not confuse the electric motor part with other brushes used as a replaceable working tool for an angle grinder. For example, with a wire stripper, also called a “cord brush” or “brush brush”.

Prevention

The problem of sparking grinder brushes can be prevented by taking preventive measures:

• follow the operating rules;
• regularly change the lubricant in the gearbox and bearing sections, reducing mechanical and thermal loads (factory lubricant must be replaced before starting any work);
• promptly replace bearings while maintaining the structural integrity of the armature shaft;
• install a new set of brushes before the old ones start sparking .

If you notice that the brushes spark and burn, you should immediately check the tool or contact a specialist. The lack of timely diagnostics of angle grinders leads to the fact that the sparking brush block ultimately breaks the entire power tool.

If the brushes on the grinder sparkle. Repair for 200 rubles

You will learn how to replace faulty brushes in an angle grinder in the following video.

Sparks are a fairly common occurrence when operating electrical appliances. Sometimes it doesn't mean anything. But there are times when sparks indicate a serious breakdown or other unpleasant problems. A vacuum cleaner in this sense is no exception. Why brushes spark in a vacuum cleaner and how to troubleshoot problems - we’ll talk about this now.

Changing the angle of inclination

If the angle of inclination of the brushes relative to the stator is incorrect, sparking may also occur. The correct position is when both brushes are strictly on the same line passing through the axis of rotation of the commutator. Over time, due to constant vibration, the brush holder mount may become loose or even suffer mechanical damage. Carefully inspect the surfaces of the components. Parts that have cracks, chips or signs of corrosion must be replaced.

Each manufacturer introduces design features into its product line, and therefore different types of vacuum cleaners have different types of brush attachment. However, in general, all models have the same device, and the brush holder is usually screwed on with two screws and allows for adjustment.

Why do the brushes on an angle grinder spark a lot?

As for the electromagnetic factors that cause carbon brushes for electric motors to spark, they are more difficult to identify. Sparking, which appears due to various electromagnetic phenomena, varies proportionally to the load and depends little on the rotation speed.

If the brushes are already badly worn, simply due to the age of the engine, then the engine will not be able to reach full speed and reach full power. In this case, the sparking will be very strong, and the engine will not start the first time.

This may be due to a broken, dislodged or stretched spring. Try pressing the button from different angles. If it works, then it’s a matter of dismounting. You can get to it in the following way:

• Remove the vacuum cleaner body;
• Remove the drum, lever spring, lever itself and brake roller;
• Replace the spring if necessary. Here you can adjust the degree of tension of the cord;
• Reassemble all the parts in reverse order and check how the cord is wound.

READ In which direction are the sparks from the grinder?

A similar malfunction is possible inside the stator when part of the winding overheats and strong sparking is observed near one of the brushes. Check the resistance of both halves of the stator winding, they should be the same. If one part of the stator winding has a resistance much lower than the other, then rewinding or replacement of the stator is required.

What are they made from?

Brushes for grinders and other power tools are made from different materials, but the main ones are coal and graphite. This material has a low coefficient of friction and also has increased abrasion resistance. To improve contact, various impurities are added to the composition of graphite or carbon during the manufacture of brushes. Depending on the impurities used, the following types of brushes are distinguished:

• Coal
• Copper plated
• Carbon-graphite
• Graphite
• Copper-coal
• Copper-graphite

The composition of the main part affects not only the service life or wear, but also such a parameter as signs of sparking. The amount of brush sparking depends on the composition from which they are made

When purchasing them, you need to pay attention to the composition, and not purchase equipment of unknown origin and questionable quality.

This is interesting! The design of the brushes contains a ceramic tip, which performs one of the important tasks. When the graphite layer is abraded to the limit, the tip begins to contact the copper lamellas of the commutator. Ceramics do not conduct electricity, so when the brushes wear out, the grinder will work intermittently or will not turn on at all until the devices are replaced.

Why do brushes spark in an electric motor?

Sparks, including on a working engine, appear due to mechanical action between the brushes and the commutator. The brush , moving along the commutator from one of its contacts to another, alternately forms and breaks a connection with each of them. Now remember what happens if you unplug any working electrical appliance from the socket - usually at such a moment a spark jumps between the plug and the socket. In the case of a brushed motor, this is the same phenomenon.

Therefore, a small spark even on a working electric motor is acceptable, since connections and ruptures constantly occur here.

Sparking degree

The quality of switching, according to GOST 183-74 (Table 1), is assessed by the degree of sparking (switching class) under the running edge of the brush, that is, under the edge from which the commutator plates emerge during their rotation.
The degree of sparking is 1, 1¼ and 1½ and are allowed under any operating conditions. Table 1

Degree of sparking (switching class) of electrical machines

Why do motor brushes spark?

Commutator electric motors differ from other types of motors by the presence of a commutator-brush assembly. The unit provides an electrical connection between the rotor circuit and circuits located in the stationary part of the motor, and includes a commutator (a set of contacts located directly on the rotor) and brushes (sliding contacts located outside the rotor and pressed against the commutator).

When operating a commutator motor in a power tool, you can sometimes observe sparking of the brushes. In some cases, this symptom leads to rapid breakdown of the power tool, and in others. doesn't bode well. One way or another, it is useful in each case to understand the cause of the sparking, so that, if necessary, the correct measures can be taken in a timely manner. In this article we will look at the causes of sparking brushes, as well as measures to combat the problems that cause this phenomenon.

It is obvious that intermittent mechanical contact of the brushes with the commutator cannot but lead to sparking, because in fact, the electrical circuit of the rotor is broken and closed again many times per second.

The rotor contains a winding, which is a predominantly inductive load. The rupture of such a circuit is inevitably accompanied by a transient process, which is associated with the appearance of small arcs from the self-induction of the rotor winding or the rotor and stator windings. Of course, brushes wear out over time, as do commutator plates, but sometimes problems arise even before they wear out.

In fairness, we note that for the reason mentioned above, even a serviceable commutator engine cannot operate without sparks at all; there is always a small spark on the commutator. A fully functional device normally reaches full power, develops operating speeds and still sparks a little. It’s another matter if the sparking is strong - there is a reasonable concern here.

Sparking brushes as a sign of wear

If the brushes are already badly worn, simply due to the age of the engine, then the engine will not be able to reach full speed and reach full power. In this case, the sparking will be very strong, and the engine will not start the first time.

How to check that this is exactly the case? If the worn brushes are pressed against the commutator with a screwdriver, the contact will become tight and the engine will start working. But as soon as the clamp is loosened, sparks will appear again - the distance between the plates and brushes will become filled with small arcs. The brushes are clearly worn out and should be replaced with new ones. Sometimes replacement is only possible all together. with brush holders and springs.

There may be a short circuit in the rotor winding

The armature (rotor) winding of a commutator motor traditionally contains several sections. If at least one is damaged, if there is an interturn short circuit, then more current will be supplied to one section than to the others. This will lead to overheating of the winding in one place, and to uneven sparking on the collector - sparks will be stronger at certain transitions on the plates than at others. This requires rewinding the anchor or a completely new anchor.

Is the stator winding OK?

A similar malfunction is possible inside the stator when part of the winding overheats and strong sparking is observed near one of the brushes. Check the resistance of both halves of the stator winding, they should be the same. If one part of the stator winding has a resistance much lower than the other, then rewinding or replacement of the stator is required.

A dirty collector causes an unnecessary short circuit on it, resulting in unnecessary sparks

Dust on the commutator is formed as a result of gradual wear of the brushes - this is graphite dust. It accumulates between the plates (lamellas) of the collector and creates “unauthorized” short circuits. Sparks appear due to short circuits. Simply clean the collector with sandpaper, removing dirt between the lamellas.

Be sure to check how the brushes are located, whether one of them is displaced relative to its normal position, and adjust the brushes if necessary. When the brushes are positioned crookedly, graphite dust is formed in disproportionately large quantities than when the brushes are positioned correctly.

Another cause of contamination is carbon deposits on the manifold due to overheating. When all other causes of sparking have been eliminated, it is necessary to clean the contacts from carbon deposits to improve the contact of the brushes with them.

If the contact is good, the resistance does not increase beyond the nominal value, and unnecessary sparks do not occur. You can clean off carbon deposits like graphite dust. sandpaper, only rotating the rotor with the commutator clamped in special pads.

Sources:

https://stroy-podskazka.ru/instrumenty/boLGarka/neispravnosti-shchetok/ https://kupihome.ru/nastrojka/pochemu-iskryat-shhetki-v-pylesose-prichiny-i-reshenie-problemy.html https:/ /electrik.info/remont/1288-pochemu-iskryat-schetki-elektrodvigatelya.html

Engine diagram

For a more visual understanding of the operating principle of a commutator motor, there are two visual types of representation - simplified and detailed.
The first format (Figure below) is a conventional diagram, focusing on connecting the windings to the network

More complex designs (Fig. below) have additional taps on the rotor and stator. For example, to power automation or regulate speed. The presence of thermal protection allows you to minimize the likelihood of overheating of the upper layer of the unit winding. This element removes voltage when the relay is activated, stopping the operation of the shaft.

The tachogenerator reflects the rotation speed of the engine. As an alternative, a Hall sensor is installed on some models. The device receives signals through the contacts of the collector panels.

Angle grinder device

To understand the operation of the mechanism and why breakdowns are possible, you need to have an idea, at least schematically, of the main components of the tool.

Regardless of the model, manufacturer and technical characteristics, any angle grinder has the following details:

• The moving part of an electric motor is called an armature, or, what would be technically correct, a rotor. As a rule, this element is combined with a working shaft that transmits torque.
• Contacts of the collector, which is a switching board, through which the voltage is removed from the current collectors.
• Brushes pressed against it provide electrical contact. When pressed lightly, they begin to spark strongly.
• The internal stationary winding is the stator. The rotation of the armature in it is achieved due to electromagnetic induction.
• Mechanical reduction gearbox for speed regulation.
• Other components: housing, usually plastic, handles, start button, power cable.

As a working tool, an angle grinder is subjected to high loads and increased continuous operation time. Despite the maximum tightness, dust, small fragments of processed materials, and scale periodically get inside the housing. This negatively affects both the mechanical parts and the electrical part.

As a result, the conductive parts become contaminated and the collector lamellas gradually burn out due to overheating. In turn, this leads to destruction of the current collecting brushes, which will be signaled by increased sparking.

Control Panel

Automatic washing machines produced by other brands are equipped with an electronic control module.
He adjusts the washing parameters and is responsible for ensuring that the machine operates with minimal human intervention. Sparks when the control unit breaks down occur extremely rarely. The malfunction at the initial stage is manifested by failures in washing programs and blinking indicators. Then the control panel will stop responding to button presses, the machine will not turn on or refuse to perform its functions.

Repairs are possible, but are rarely done. More often, a complete replacement of the control unit is required to ensure flawless operation of the equipment.

Prevention of collector devices

In order to extend the life of the armature, and, accordingly, the electric tool itself, it is necessary to follow a few simple rules. These measures are as follows:

• Do not allow the device to operate for a long time at low speeds under a significant load, and especially not to allow the cutting part to bite. When an electric motor jams, a short blocking time is enough for it to burn out.
• If the device is jammed, it must be carefully released and allowed to idle for two minutes. During this time, due to natural cooling, the heated parts will cool down a little.
• Observe the timing of adding or replacing lubricants.
• If vibration or noise occurs, it is necessary to carry out a preventive inspection by disassembling the housing and cleaning both the collector and the entire space inside from dirt.