The motor brushes of power tools spark: the reason is that they spark strongly at the armature of a drill or grinder

Posted on March 31, 2017 by Johhny

During operation, devices with a commutator motor may spark. Strong sparking often indicates imminent tool failure. It is necessary to promptly understand the reasons for the occurrence of increased sparking and take measures to eliminate it. The article discusses the most likely reasons for the occurrence of this negative phenomenon.

The basis of devices with AC electric motors is a brush-commutator module, which ensures electrical contact of the rotor with the static part of the electrical device. This module consists of two parts: a commutator located on the rotor and brushes - sliding contacts located outside the rotor part and pressed against the commutator. Sparking on a commutator motor occurs as a result of the mechanical interaction of moving and stationary parts. The contact between the commutator and the brushes is periodically interrupted, which leads to a transient process in the electrical circuit and entails the appearance of a spark. The motor commutator brushes are the most short-lived part of the design. Therefore, over time, various problems associated with their operation may occur.

Even on a serviceable electric motor, there is usually weak sparking from the brushes. If the electrical appliance turns on normally, develops speed at full power, and sparking is hardly noticeable, then there is no reason to worry.

Causes of electric motor brushes sparking

Let's look at the most common faults of the brush-commutator unit.

1) Wear of brushes. If these elements are severely worn, the electric motor does not develop speed at full power, and may also not turn on (continuously or periodically). In this case, when the electrical appliance is turned on, you can press the brush against the armature with a screwdriver with an insulated handle. 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. Sometimes the brush holder springs also need to be replaced.

2) Interturn closure of the armature winding. A malfunction of devices with electric motors may be a broken armature. In this case, sparking will be observed in the area of both brushes, in addition, the armature winding will become very hot due to the fact that some contacts receive a larger current than others. When repairing this malfunction, the armature winding is rewound or the part is completely replaced.

3) Stator failure. When a stator breaks, usually only one of the brushes sparks. To check it, you need to measure the resistance of the windings. The same resistance of both windings (usually 4 ohms) indicates a working stator. Different resistance on the windings indicates that the stator is faulty and its winding needs to be rewound.

4) Closing the collector contacts. As a result of contact wear, graphite dust is formed, which accumulates between them, shorting them. In this case, large sparks are observed during operation of the electrical appliance. To eliminate the breakdown, it is necessary to clean the spaces between the contacts from graphite dust. It is also necessary to check the commutator brushes, since if they are correctly positioned and in the correct shape, dust appears in minimal quantities.

5) Contamination of the collector contacts. If the contacts are contaminated with carbon deposits, both brushes will spark, and the electric motor will not be able to reach full speed. Carbon deposits appear on the manifold when it overheats. Poor electrical contact will lead to an increase in resistance in the element, which in turn will lead to even more sparking and carbon deposits. In this case, it is necessary to clean the collector contacts from carbon deposits. This is done with sandpaper of minimal grit. It is important when cleaning not to damage the shape of the contacts. Therefore, special pads must be used for cleaning. At home, you can use a screwdriver for cleaning. The armature is clamped into the cartridge, rotating at minimum speed, and carefully placing the sandpaper against the commutator. The direction of rotation of the armature during cleaning must coincide with the direction of its rotation in the electrical appliance.

So, your drill sparks on the brushes and you don’t know what to do in this situation. This article will tell you why this happens, whether it needs to be fixed, and if so, how.

It is immediately worth noting that the presence of the specified sparking during operation is a completely acceptable phenomenon. This is true only if the sparks are small and there are not so many of them. If they just fall out, this may indicate a malfunction.

Note that on a new, working power tool, the brushes may also spark strongly at first, since they need to first get used to. Grinding in usually takes 10-15 minutes of work. If after this everything remains as it was, then it is better to take the instrument back to the store with a claim.

If your drill is no longer under warranty, you can try to fix it yourself.

But first we will describe the reasons for this phenomenon.

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.

Sparking DC machine brushes

Repair of electric motors in the cities: Moscow, St. Petersburg, Yekaterinburg, Novosibirsk, Samara, Chelyabinsk, Perm, Kazan, Krasnoyarsk

Brush sparking can be caused by a variety of causes that require maintenance personnel to closely monitor the sliding contact and brush system. The main reasons include mechanical (mechanical sparking) and electromagnetic (electromagnetic sparking).

The mechanical reasons that caused the sparking do not depend on the load. Brush sparking can be reduced by increasing or decreasing the pressure on the brushes and, if possible, decreasing the peripheral speed.

With mechanical sparking, green sparks spread across the entire width of the brush, the burn of the commutator is not regular, it is disordered.

Mechanical sparking of brushes is caused by: local or general beating, scuffing on the sliding surface of the commutator, scratches, protruding mica, poor commutator tracking (cutting mica between the commutator plates), tight or weak fit of brushes in brush holder holders, flexibility of brackets causing vibration of brushes, vibration of machines and etc.

The electromagnetic causes that cause brushes to spark are more difficult to identify. Sparking caused by electromagnetic phenomena varies proportionally to the load and depends little on the rotation speed.

Electromagnetic sparking is usually blue-white in color. The shape of the sparks is spherical or drop-shaped. The burning of the collector plates is of a natural nature, by which the cause of the sparking can be determined.

If a short circuit occurs in the winding and equalizers, the soldering is broken or a direct break occurs, the sparking will be uneven under the brushes, and the burnt plates will be located along the commutator at a distance of one pole division.

If the brushes under the bracket of one pole spark more than under the brackets of the other poles, it means that a turn or short circuit has occurred in the windings of individual main or additional poles; The brushes are incorrectly positioned or their width is larger than permissible.

In addition, additional disturbances may be observed in DC machines: displacement of the brush cross-arm from the neutral causes sparking and heating of the brushes and commutator; deformation of the sliding surface of the commutator causes vibration and sparking of the brushes; non-symmetry of the magnetic field causes a decrease in the threshold of the reactive emf, deteriorates the switching ability of the machine, which, in turn, causes sparking of the brushes.

The magnetic field of the machine is symmetrical if the correct circumferential pitch between the tips of the main and additional poles is strictly observed and the calculated gaps under the poles are maintained.

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.

Causes of sparking

From a practical point of view, it is important that commutation occurs without significant sparking at the contact surfaces of the brushes, since strong sparking damages the surface of the commutator and brushes and makes long-term operation of the machine impossible. The causes of sparking on brushes can be divided into mechanical and electromagnetic

The causes of sparking on brushes can be divided into mechanical and electromagnetic.

Mechanical causes of sparking are mostly related to poor contact between the brush and commutator. Such violations are caused by: 1) uneven surface of the commutator, 2) poor grinding of the brushes to the commutator, 3) breakage of the commutator, if it exceeds 0.2 - 0.3 mm, 4) protrusion of individual commutator plates, 5) protrusion of mica between the commutator plates, 6) sticking of brushes in brush holders (tight fit), 7) vibration of brushes (softness of the current collector, poor balancing of the machine, too loose arrangement of brushes in brush holders with gaps of more than 0.2 - 0.3 mm, too large a distance between the brush holder holder and the commutator - more than 2 - 3 mm and so on). Sparking can also be caused by uneven tension of brush springs, asymmetrical distribution of brush fingers and brushes around the circumference and other mechanical reasons.

Electromagnetic causes of sparking on brushes are associated with the nature of electromagnetic processes in switched sections

Ensuring a sufficiently favorable course of these processes is an important task when creating DC machines, especially large ones.

Why do brushes spark in an electric motor, what does this phenomenon lead to and how can it be eliminated.

Topic: what to do if the brushes in an electric motor spark strongly.

So, from the beginning I will say that the sparking itself during the operation of collector electric machines is normal, only it should be very small, barely noticeable to the eye. It’s not normal when the electric motor is running and sparks fly out from its brushes - that’s bad. The very phenomenon of spark formation is associated with intermittent electrical contact that occurs during the rotation of the armature, at the moment of mechanical transition of the brush from one contact, on the commutator, to another. At this time, the circuit breaks and the current flowing through the armature coils ends its passage with a spark, a small arc discharge. Therefore, the greater the power and current in the circuit, the more noticeable the spark will be. But besides this, there are other factors that contribute to an increase in spark.

You should also pay attention to the condition of the gaps between the contacts on the collector. It often happens that they are clogged with graphite dust, which is a conductor with a certain resistance. Naturally, if these gaps are dirty, then you also put them in order (clean them with a sharp tool)

Don’t forget to check the condition of the brushes, their performance, clamping force, and freedom of vertical movement. If problems are identified with the brushes, be sure to fix them. Please note that when replacing graphite brushes, you should take into account that they are different. In this case, try to find exactly the same type as the old ones.

Naturally, if these gaps are dirty, then you also put them in order (clean them with a sharp tool). Don’t forget to check the condition of the brushes, their performance, clamping force, and freedom of vertical movement. If problems are identified with the brushes, be sure to fix them.

Please note that when replacing graphite brushes, you should take into account that they are different. In this case, try to find exactly the same type as the old ones.

The armature should be checked in an alternating electromagnetic field. If there are short-circuited turns, then in such a field the armature will begin to rattle, since induced currents will begin to form in it. To do this, you can make a homemade device from a power transformer, first making a wedge-shaped cutout on its core, into which you need to insert an armature for testing.

Since this is important, I repeat once again - increased spark formation during operation of the electric motor affects its service life. In this case, strong carbon deposits quickly appear on the contacts of the collector, which after a while will damage the electrical equipment. It’s better to eliminate sparks right away than to replace the whole armature later.

It is better to eliminate the sparks immediately than to replace the entire armature later.

Brushes spark due to excessive wear

Severe sparking of the brushes can occur due to the fact that they are heavily worn. In this case, accompanying signs of wear, in addition to abundant sparks, will be the inability of the engine to develop full speed and reach full power, as well as a difficult start of the engine, which is not possible on the first try. It is quite easy to check for brush wear: the brushes should be pressed against the commutator using a screwdriver. If the brushes are worn out, then with this pressure the contact density will be normalized and engine operation will improve, but when the pressure is released, sparks will appear again. In this case, there is only one solution to the problem: replacing the brushes with new ones. Some models of commutator motors provide for replacing brushes only together with springs and holders.

Replacing brushes in a washing machine

Replacing brushes in a washing machine is a relatively simple task if you already have experience repairing motors in household appliances. Today you can buy new brushes both in specialized stores and online. The main thing is to choose brushes that are suitable specifically for your model of machine. It is also worth taking original components for replacement to be sure that the new brushes will last as long or even longer than the previous ones.

The washing machine will need to be disconnected from the power supply, and if the design requires it, then the hoses will need to be disconnected. The engine will have to be completely removed, untwisted and the brush rod inspected. The length of the spent rod is usually less than 1.5 cm, and if you see that the remaining part of the brush is longer, then the problem lies in another element of the machine.

After replacing parts, you need to do a test run of any washing mode. If installation is successful, the drum will rotate normally, without any extraneous knocking or grinding noise.

However, if you have even the slightest doubt about your ability to disassemble and then correctly assemble the car and its engine, then it is better not to risk it. Contact the service center for help so that in addition to the main breakdown, the technician does not have to eliminate the consequences of your inept intervention.

The average owner of household appliances thinks little about what elements and parts the equipment consists of, what problems and malfunctions can arise if used incorrectly, and what problems arise without human presence. Therefore, when hearing the term washing machine brushes, many will think of an item designed to care for and clean the unit. But this element is the most important for the life and functioning of the machine. In this article we will tell you what function brushes perform, how to find out if the brushes for electric motors of washing machines are worn out, and how to replace them.

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.

How to fix and what to do if the vacuum cleaner motor brushes spark

If the household unit begins to work worse, and standard cleaning of blockages does not bring results, it is necessary, first of all, to disassemble the engine. What to do if the vacuum cleaner motor sparks depends on the type of problem.

How to replace worn brushes

Most often, the vacuum cleaner engine sparks in the area of the brushes precisely because of the natural wear of the latter. Although modern models have special capacitors that slow down abrasion, sooner or later contact between the elements leads to unpleasant problems.

Worn parts need to be replaced. To remove them, you need to remove the back cover of the vacuum cleaner, find the brush holders and pull the latches with your hands or a screwdriver. Then all that remains is to purchase exactly the same elements.

Old brushes can wear down to the springs

In order not to make a mistake with your choice, you can go to the store with the old removed parts and, with the help of a consultant, buy similar ones. Then they are installed in the old place, secured with latches and the vacuum cleaner is assembled in the reverse order.

How to eliminate poor contact of new brushes

If the vacuum cleaner is completely new, or the brushes have recently been replaced, and the motor still sparks, the reason may be a poor fit to the commutator. The problem can be solved quite simply. The engine compartment is opened, the engine is removed and the protective casing is removed from it.

It is necessary to polish the vacuum cleaner brushes with the finest abrasive.

It is necessary to go over the installed brushes with sandpaper to eliminate the smallest roughness. You can also use abrasive sandpaper to treat the collector plates if they have scratches. The smoother the contacting surfaces are, the less likely it is that the vacuum cleaner will start sparking.

How to change the angle of the brushes

If the brushes are skewed relative to the commutator after prolonged use of the vacuum cleaner, sparks will occur when the engine operates. To resolve the problem you must:

remove the motor from the vacuum cleaner;
visually determine how correctly the brushes are positioned relative to the commutator axis;
Use a screwdriver to tighten the two screws securing the brush holder to align the elements.

In old vacuum cleaners, you need to carefully examine the condition of the connecting nodes between the collector and brushes. If traces of corrosion and even cracks are visible on them, such elements must be replaced with new ones.

When the axis is knocked down, the brushes begin to contact the commutator loosely

How to clean dirt

Coal dust and the resulting carbon impair the friction between the brushes and commutator and cause the engine to spark. The problem can be resolved by regular cleaning. The motor is removed from the unit and the casing is removed, after which the brushes are disconnected and access to the commutator is opened. If dirt is noticeable on the surface of the parts, they are treated with fine sandpaper until completely clean.

Plaque accumulates on the brushes and commutator, so when cleaning they are additionally degreased with alcohol. Tip! During operation, you should pay attention to the rotor contacts. If graphite dust and dirt have also accumulated between them, it must be carefully cleaned out.

How to eliminate a short circuit in the winding

Sometimes replacing brushes and other actions do not produce any results, and the vacuum cleaner continues to spark strongly. Usually the problem is an interturn short circuit of the commutator. There are two ways out of the situation - you need to either completely change the winding or replace the unit’s motor.

When a short circuit occurs, noticeable blackening appears on the collector plates

Rewinding an armature requires some experience and specialized knowledge in electrical engineering. Therefore, it is easier to send the engine for service or immediately purchase a new engine. This will be expensive, but buying just an anchor usually doesn't make sense. Its price is about 80% of the cost of the entire motor.

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

Sparking degree (switching class)	Characteristics of the degree of sparking	Commutator and brush condition
1 1¼	No sparking (dark switching) Weak spot sparking under a small part of the brush	– No blackening on the commutator or carbon deposits on the brushes
1½	Weak sparking under most of the brush	The appearance of traces of blackening on the commutator, which can be easily removed by wiping the surface of the commutator with gasoline, as well as traces of carbon deposits on the brushes
2	Sparking under the entire edge of the brush. Allowed only for short-term load shocks and overloads	The appearance of traces of blackening on the commutator, which cannot be eliminated by wiping the commutator with gasoline, as well as traces of carbon deposits on the brushes
3	Significant sparking under the entire edge of the brush with large and flying sparks. Allowed only for moments of direct (without rheostat stages) switching on or reversing machines, if the commutator and brushes remain in a condition suitable for further operation	Significant blackening on the commutator, which cannot be eliminated by wiping the surface of the commutator with gasoline, as well as scorch and destruction of the brushes

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.

Reasons why brushes spark

Very often you can notice how the brushes on an angle grinder sparkle. Signs of sparking are detected through the ventilation holes in the body of the power tool. Craftsmen are interested in why the brushes on an angle grinder spark, even after they have been directly replaced. There are many reasons for this, and to understand this, you need to have an understanding of the structure of a power tool. If you know how the angle grinder works inside, then understanding why the brushes spark strongly will not be difficult.

The reasons for strong sparking of brushes on grinders are the following factors:

Faulty armature winding. If a violation of the insulation of the armature winding occurs, then this ultimately contributes to the development of an interturn short circuit, as well as a short circuit to the core. In addition, a winding break may occur, which will ultimately cause an increase in load. A characteristic sign of a faulty armature winding is a decrease in speed, an increase in noise and a drop in power
The brushes do not press well to the commutator. A spring is responsible for pressing the main part, which, over time, loses its original springing properties.
The rotor winding has broken off from the copper plate of the commutator - this phenomenon is extremely rare, however, if the power tool is overloaded, it may well occur
The centering of the electric motor armature is disrupted, which ultimately contributes to strong sparking of the brush on the angle grinder
The shape of the collector is broken. The collector, consisting of copper lamellas, has a cylindrical shape, which can be broken when the rotor is rewinding. At the slightest deformation of the commutator shape, sparking of the brushes will occur
Violation of insulation between the collector lamellas. Each collector plate is insulated from each other, and if the micanite insulating layer is damaged, sparking occurs. The insulation between the plates may also be compromised due to the settling of the graphite layer in the grooves
When the armature bearings are worn. If the bearings are faulty, then a beating of the rotating armature occurs, and as a result, signs of sparking appear
Curvature of the rotor shaft. It is difficult to bend it, but if this happens, the engine begins to work under load. To prevent the tool from malfunctioning, it is recommended to replace the rotor
If the ends of the armature windings are soldered incorrectly to the copper plates of the collector. Such errors are not allowed at the factory, but they can be made by the wrapper who rewinds the armature of the power tool.
Inappropriate composition of graphite brushes. The parts in question are made from coal and graphite, adding different types of impurities. This is done for a reason, but in order to use brushes depending on the voltage and shaft rotation speed. Graphite can be soft or hard. The lower the supply voltage, the softer the grade of graphite selected. For high-voltage power tools, it is necessary to take hard brushes that do not contain copper.
Deformation of the lamellas due to their heating. If the angle grinder experiences excessive loads, deformation of one or more lamellas of the collector may occur. The plates rise relative to the others, resulting in the contact being broken. This malfunction causes strong sparking of the brushes when operating the power tool.
Poor contact at the brush connection point. If the terminal is loosely connected to the device, the result of this contact failure may manifest itself in the form of excessive sparking
Presence of carbon deposits on copper plates - periodically or regularly it is recommended to clean the surface of copper lamellas from carbon deposits. Carbon deposits usually appear due to wear of the brushes, so if blackening is detected on the surface of the commutator, it should be wiped with alcohol

Often, after changing the brushes on an angle grinder, craftsmen observe the phenomenon of excessive sparking. Based on the factors described above, you can identify the cause and eliminate it before the tool fails. The elements in question are inexpensive, but due to their incorrect selection and use, the power tool may break. To find out what malfunction is causing strong sparking, you will need to disassemble the power tool and inspect it, as well as ring the rotor winding.

The motor brushes of power tools spark: the reason is that they spark strongly at the armature of a drill or grinder

Commutator motors are widely used in household electrical equipment. Small dimensions, lightness, and ease of operation determined their presence in grinders, rotary hammers, circular saws, and screwdrivers. The main disadvantage is increased wear of the brush-collector pair. The failure of this unit is predetermined by the sparking that occurs in it.

Electric motor design and operating principle

The operating principle of an electric motor is based on the interaction of a conductor with a current located in a magnetic field.

The magnetic field is created by the stator.

The main element of its design for a DC motor is a permanent magnet, for alternating current it is an excitation winding. The rotor (armature) has its own winding, to which voltage is supplied using a brush-commutator unit. The interaction of magnetic fields causes the rotor to rotate.

The collector consists of a set of contacts, which are copper plates located directly on the rotor. Micanite or mica cuffs act as insulators for each individual contact. Graphite brushes are sliding contacts pressed against the commutator.

Causes

Transient processes occur in the rotor windings due to intermittent mechanical contact of the brushes with the commutator plates, which causes the formation of small arcs.

Important: a fully serviceable engine does not exclude sparking during operation. There are other reasons that cause severe sparking and create the possibility of motor failure

Brush wear

With prolonged use or poor-quality brush material, they no longer press tightly against the contacts of the commutator. Due to poor contact, the engine does not gain speed or does not start immediately. A worn brush can be easily identified visually.

Sometimes it is not possible to correct the situation by replacing only the worn part. The brush holder and spring should be replaced.

Short circuit in the armature winding

The consequence of such a defect is uneven sparking on the collector. It will be stronger on some plates than others. Due to the presence of an interturn short circuit, the current in certain sections of the rotor winding will be stronger than in others.

Rewinding the rotor or replacing it will eliminate the problem.

Fault in the stator winding

A defect similar to a short circuit in the rotor winding occurs in the stator winding. You can check the presence by measuring the resistance of parts of its windings. If there is a strong difference, it is necessary to rewind the winding or replace it.

Pollution

The product of brush wear is graphite dust, which is an additional source of increased sparking. Dust accumulates between the plates, which creates additional conditions for the formation of sparks. Preventive cleaning of the commutator with sandpaper and removing dirt between the plates will keep it clean.

Brushes not installed correctly

If the brushes are deviated from the norm towards the commutator surface, a significantly larger amount of graphite dust is generated during operation. Misaligned brushes must be corrected.

Poor contact between brushes and commutator

The electric motor spends part of its operating time in overheating mode. Under such conditions, carbon deposits form on the collector. Poor contact leads to increased brush sparking and even more carbon deposits.

You need to use fine-grain sandpaper to clean the surface of the commutator. To increase the stripping effect, use a screwdriver. Clamp the engine rotor into the chuck and remove carbon deposits with sandpaper at low speeds. Afterwards you need to finally polish it on a felt wheel.

Mechanical problems

Mechanical reasons are caused by non-compliance with the requirements of design and technological documentation. Most mechanical causes can be eliminated by turning the manifold on a lathe. Refer this repair operation to a qualified technician. Here are some types of faults that may indicate a breakdown:

The surface of the collector is uneven;
The shaft runout exceeds the value specified in the technical documentation;
Individual collector plates protrude beyond a common level for all;
Insulation protrusion (mica);
The brushes in the brush holders move with jamming;
On the contrary, the brushes are inserted into the brush holders with a large gap, which creates vibration during operation;
The brush holders are installed far from the commutator;
Uneven tension of the springs, resulting in a difference in the pressure applied to the brushes.

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.

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.

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.

Consequences of sparking

Due to sparking, metal evaporates from the contacts, heating them up and increasing the contact resistance. The latter causes them to burn even more, after which they spark even more. The consequences of these processes can lead to a partial or complete lack of switching ability of the device, even to the point of sticking or fire under certain circumstances. It is necessary to monitor the condition of all connections and moving switching elements.

What are they made from?

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

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

Purpose of brushes on angle grinders

Before you find out the reasons for sparking brushes on an angle grinder, you need to understand their purpose. Commutator brushes are used not only in the design of angle grinders, but also in the design of all modern power tools - drills, hammer drills, jigsaws and others. In the design of grinders and other power tools, 2 brushes are used, which have a simple design. This design is based on the following elements:

The main part is rectangular in shape and made of coal or graphite
A contact is a wire core of the appropriate diameter through which electric current flows. The contact connects the wire to the graphite part
A spring is a mechanism that ensures the main part is pressed against the collector. There may be no spring on the element, and this indicates that such a brush is intended for installation in a power tool, where the brush holders have a built-in pressing mechanism in the form of a curved plate

The devices are designed to transmit electric current to the rotor of a power tool. The voltage removed from the stator is supplied to the rotor, which is reproduced using carbon brushes and a commutator. Supplying current to the collector ensures its rotation. When the rotor rotates, the devices come into contact with the collector (copper lamellas are the leads of the armature windings), thereby ensuring the continuous flow of electric current.

Read also: Iron for a toroidal transformer

During the use of devices, they wear out, so they are classified as consumables. The service life of brushes depends not only on the working life of the power tool, but also on the materials from which they are made. The wear of brushes is affected not only by mechanical impact due to friction, but also by thermal impact. Electric current passing through a conductor causes it to heat up. The higher the current, the higher the heating temperature. When current passes through the graphite brushes, they also heat up. The higher the load on a power tool, the higher the current, which means the temperature increases, which negatively affects the integrity of consumables.

Reasons why brushes spark

https://youtube.com/watch?v=W-k9JyxuWik%3F

The reasons for strong sparking of brushes on grinders are the following factors:

Faulty armature winding. If a violation of the insulation of the armature winding occurs, then this ultimately contributes to the development of an interturn short circuit, as well as a short circuit to the core. In addition, a winding break may occur, which will ultimately cause an increase in load. A characteristic sign of a faulty armature winding is a decrease in speed, an increase in noise and a drop in power
The brushes do not press well to the commutator. A spring is responsible for pressing the main part, which, over time, loses its original springing properties.
The rotor winding has broken off from the copper plate of the commutator - this phenomenon is extremely rare, however, if the power tool is overloaded, it may well occur
The centering of the electric motor armature is disrupted, which ultimately contributes to strong sparking of the brush on the angle grinder
The shape of the collector is broken. The collector, consisting of copper lamellas, has a cylindrical shape, which can be broken when the rotor is rewinding. At the slightest deformation of the commutator shape, sparking of the brushes will occur
Violation of insulation between the collector lamellas. Each collector plate is insulated from each other, and if the micanite insulating layer is damaged, sparking occurs. The insulation between the plates may also be compromised due to the settling of the graphite layer in the grooves
When the armature bearings are worn. If the bearings are faulty, then a beating of the rotating armature occurs, and as a result, signs of sparking appear
Curvature of the rotor shaft. It is difficult to bend it, but if this happens, the engine begins to work under load. To prevent the tool from malfunctioning, it is recommended to replace the rotor
If the ends of the armature windings are soldered incorrectly to the copper plates of the collector. Such errors are not allowed at the factory, but they can be made by the wrapper who rewinds the armature of the power tool.
Inappropriate composition of graphite brushes. The parts in question are made from coal and graphite, adding different types of impurities. This is done for a reason, but in order to use brushes depending on the voltage and shaft rotation speed. Graphite can be soft or hard. The lower the supply voltage, the softer the grade of graphite selected. For high-voltage power tools, it is necessary to take hard brushes that do not contain copper.
Deformation of the lamellas due to their heating. If the angle grinder experiences excessive loads, deformation of one or more lamellas of the collector may occur. The plates rise relative to the others, resulting in the contact being broken. This malfunction causes strong sparking of the brushes when operating the power tool.
Poor contact at the brush connection point. If the terminal is loosely connected to the device, the result of this contact failure may manifest itself in the form of excessive sparking
Presence of carbon deposits on copper plates - periodically or regularly it is recommended to clean the surface of copper lamellas from carbon deposits. Carbon deposits usually appear due to wear of the brushes, so if blackening is detected on the surface of the commutator, it should be wiped with alcohol

https://youtube.com/watch?v=JhnK8Mi2syY%3F

How to understand that you need to change the brushes

Many people change brushes only after they notice strong sparking from the tool, as well as the appearance of a burning smell. Many craftsmen are not stopped even by these signs, and they continue to use the tool until it stops turning on. When is it necessary to change carbon brushes so as not to damage the structure of the power tool? There are the following signs for this:

Strong sparking - if signs of strong sparking appear, then it is necessary to disassemble the tool and inspect the consumables. Sparking is the first sign that consumables need to be replaced.
The appearance of a burning smell - if the smell of soot is heard when using the tool, it is recommended to disassemble the grinder and replace the graphite brushes
When the wear of the main part is over 30% -40%. However, it is almost impossible to determine their initial length, unless you measure it before installing the elements
When signs such as jerking or “growling” of the power tool appear

Devices are also subject to replacement if they have uneven wear and do not correspond to quality.

This is interesting!
It is not recommended to buy copper-plated brushes for a home grinder, as they will quickly damage the armature commutator due to the high copper content in the composition.
Copper-plated elements can be used on grinders that have a special coating on the collector plates. https://youtube.com/watch?v=Wt0n_ECSwvE%3F

The drill sparks on the brushes - what to do

So, your drill sparks on the brushes and you don’t know what to do in this situation. This article will tell you why this happens, whether it needs to be fixed, and if so, how.

If your drill is no longer under warranty, you can try to fix it yourself.

But first we will describe the reasons for this phenomenon.

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.

Causes of severe sparking and how to eliminate them

Now let's move on to strong sparking. It occurs mainly for the following reasons:

contamination of collector contacts with carbon deposits
graphite dust getting between the collector contacts
interturn short circuit in the armature winding

Let's go through each point separately.

1) Soot contamination occurs as a result of engine overheating. The presence of carbon deposits leads to even more friction, which leads to even faster overheating and even more carbon deposits. Which very quickly leads to breakdown.

Excessive sparking here results from the fact that carbon deposits form additional resistance, which causes the spark to break when it breaks, becoming larger and more powerful.

In general, carbon deposits should be removed immediately.

This is done with zero grade sandpaper. That is, you need to remove the collector along with the armature and carefully clean it. Ideally, it is advisable to carry out the grinding on a lathe so as not to disturb the correctness of the circle. But, as a rule, this is not possible, so you can get by with manual stripping. The main thing is not to overdo it.

2) When using a drill, the brushes wear out, which causes the formation of graphite dust. It can easily accumulate between the collector contacts and lead to short circuits between them, since it is a conductor of electricity and has its own resistance. Because of this, the current is distributed unevenly, which leads to large sparks in some places.

In a working drill, wear occurs quite slowly, so graphite dust hardly accumulates. Accordingly, its accumulation signals that the brushes are in the wrong position during operation. This usually happens when they do not stand tightly in their groove, but, on the contrary, have some play.

This often happens when replacing brushes, when they are selected to be not quite suitable in size.

Therefore, when replacing this point, you should pay close attention.

Repair of such a malfunction is carried out by removing dust with some pointed tool and replacing the brushes with more suitable ones.

3) In the event of an interturn short circuit in the armature, the current flows in a larger value to some contacts and a smaller value to others. Because of this, more current flows in some places than necessary, resulting in large sparks.

Identifying such a short circuit should be done when the two previous points did not give much effect. It is produced using a special device that creates an alternating magnetic field. When an armature is placed in this field, it begins to rattle, as induced currents appear in it.

Some people make such a device themselves from a power transformer, in the core of which a cutout is made where the armature is placed.

If the reason turns out to be an interturn short circuit, then you need to rewind the winding or completely replace the armature.

These are the causes of excessive sparking on the drill brushes. Remember, if you don't do anything about it, the engine will most likely break down soon. Therefore, do not be lazy and follow the recommendations indicated in the article.

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Electric motor brushes - causes of sparking, methods of checking and eliminating

A distinctive feature of all electric motors is the presence of a commutator-brush assembly in their design. It provides an electrical connection between the rotor circuit and the circuits in the stationary part of the motor, and consists of a commutator (a series of contacts on the rotor itself) and a brush (moving contacts outside the rotor, pressed against the commutator).

When an electric motor is started and running, it almost always sparks. Sometimes this does not mean anything terrible, but sometimes it signals that the device will soon fail. In any case, it is useful to know why the electric motor sparks in the first place - this will help, if necessary, take timely measures. In this article, we will look at the reasons for the occurrence of sparks during operation of the electric motor and ways to combat problems that cause increased sparking.

First, let's define it - inconsistent contact between the brushes and the commutator leads to sparking by default. This is due to the fact that during operation the electrical circuit of the rotor closes and opens many times per second.

The rotor contains a winding. This winding is a load of mainly inductive nature. This, in turn, means that by breaking such a circuit, we start a transient process associated with the appearance of small arcs from the self-induction of the winding - both the rotor itself and the stator. It is clear that brushes and commutator plates wear out over time, but sometimes problems arise not only because of it.

Taking into account the above facts, it must be admitted that even a serviceable and well-fitted electric motor cannot operate without sparking at all. A working device in normal mode develops operating speed, gains power and sparks a little. But if there are a lot of sparks, this is a serious cause for concern.

Brush wear as a cause of sparking

The first and main reason for sparking is wear of the brushes. If there is significant wear, the engine will not be able to develop full speed and gain full power; in addition, it will spark very strongly and will not start immediately.

How can I determine if this is the reason? If you press the worn brushes against the commutator with a screwdriver or other tool, this will seal the contact and start the engine, but after the pressure is loosened, strong sparking will appear again - the space between the brushes and plates will be filled with small arcs. With such symptoms, we can conclude that the brushes are worn out and require replacement. Sometimes it is possible to replace the brushes separately, but more often it is necessary to replace the entire set, including the brush holder and springs.

Short circuit in the rotor winding as a cause of sparking

The rotor winding in a commutator motor consists of several sections. If one of them is damaged and an interturn short circuit occurs in it, then the current will flow into it with greater force than into the others. Because of this, part of the winding will begin to overheat and begin to generate an increased number of sparks. This is exactly how this reason can be established - sparking will increase only in a separate area, and not evenly. This can be corrected by rewinding the rotor or replacing it.

Malfunction of the stator winding as a cause of sparking

The malfunction is very similar to the previous one and is diagnosed in the same way - uneven sparking. If everything is in order with the rotor winding, then check the resistance of the stator winding - it should be the same for each half. A significant difference in resistance indicates the need to rewind or replace the stator.

Collector contamination as a cause of sparking

As the engine operates, its brushes wear out and graphite dust forms on the commutator. It accumulates between its plates and creates additional unwanted short circuits, which, in turn, spark. In this case, it will be enough to remove dust and dirt between the plates using sandpaper.

It would also be a good idea to check the position of the brushes - any deviation from the normal position greatly accelerates the formation of dust and wear of the brushes.

Another reason for contamination of the collector is carbon deposits on it due to overheating during operation. When all other causes of sparking on engines have been checked and eliminated, clean the commutator contacts from carbon deposits - this will improve the contact of the brushes with it and reduce the number of sparks generated. Carbon deposits are removed in the same way as graphite dust - with sandpaper. The only difference is that the rotor must be rotated while the commutator is clamped.

Read further:

Why do brushes spark in a power saw?

Why do brushes on a drill burn?

Why do the brushes on a vacuum cleaner burn?

How to check generator brushes with a multimeter

Why do sockets spark when plugged in?

Replacing brushes

The simplest and most obvious cause of sparks is wear on the brushes. Despite the fact that commutator motors are equipped with special spark-extinguishing capacitors, which, in addition to increasing the service life of these elements, also reduce radio interference, over time the brushes wear out and need to be replaced.

To replace the brushes, you first need to get to the electric motor. To do this you will have to disassemble the vacuum cleaner. In most cases, this is quite simple to do with a screwdriver, but do not forget to unplug the device. Having disassembled the vacuum cleaner and provided convenient access to the engine, we find the brush holders. Depending on the design, to remove the brushes from the brush holder, you usually need to pull out the latches, which may require a screwdriver.

In recent years, many manufacturers have supplied their vacuum cleaners with a set of spare brushes. But if you happen to purchase the device without additional spare parts, they can be purchased at stores that sell power tools.

Brushes are graphite and copper-graphite. It will be better if you remove the old elements from the electric motor of your vacuum cleaner in advance and go to the store with them, so as not to make a mistake in your choice.