Angle grinder armature sparks how to fix. Failure in the stator winding

Causes of brush arcing on the angle grinder

Very often you can see how the brushes on the angle grinder spark. Signs of arcing are detected through the air vents in the body of the power tool. Masters wonder why the brushes on the angle grinder spark, even after replacing them directly. There are many reasons for this, and to understand it, you need to have an understanding of the device of the power tool. If you know how an angle grinder is arranged inside, it is not very difficult to understand why the brushes spark strongly.

Causes of strong sparking of brushes on bolsters are the following factors:

  • Faults in the armature winding. If there is a violation of the insulation of the armature winding, it eventually contributes to the development of an inter-turn short circuit, as well as a short circuit to the core. In addition, winding breakage can occur, which eventually causes an increase in load. Armature winding defect is characterized by low speed, increased noise and power loss
  • Brushes are not adhering properly to the collector. For clamping the main part is responsible for the spring, which loses its original springing properties over time of operation
  • The rotor winding breaks off the copper plate on the collector. this is very rare, but if the power tool is overloaded, it is likely to occur
  • The alignment of the electric motor armature is disturbed, which ultimately contributes to strong brush arcing on the angle grinder
  • Collector shape disturbed. Collector, consisting of copper lamellas, has a cylindrical shape, which can be disturbed when the rotor is rewound. If the collector is distorted in any way, the brushes will spark
  • Isolation between collector blades broken. Each collector plate is insulated to each other, and if the micanite insulating layer is breached, arcing will occur. The insulation between the plates can also be compromised by the settling of the graphite layer in the grooves
  • When the armature bearings are worn. If the bearings are defective, the rotating armature will run out and consequently exhibit symptoms of arcing
  • Rotor shaft distortion. It is difficult to bend it, but if it does, then the engine begins to run with the load. To prevent the tool from failing, it is advisable to replace the rotor
  • If the armature winding ends are not properly brazed to the copper collector plates. These mistakes are not made at the factory, but they can be made by the person rewinding the electric tool armature
  • Unsuitable composition of the graphite brushes. The parts in question are made of carbon and graphite with the addition of various types of impurities. This is done for a reason, but in order to use the brushes depending on the voltage and speed of rotation of the shaft. Graphite can be either soft or hard. The lower the supply voltage, the softer the graphite grade is chosen. Use only hard brushes with copper-free components for high-voltage power tools
  • Deformation of the lamellae due to heat. If the angle grinder is overloaded, one or more of the collector lamellae may become deformed. The plates are raised relative to the others, resulting in poor contact. This defect causes the brushes to spark very badly when the power tool is running
  • Poor contact at brush connections. If the terminal is not securely connected to the machine, the result of this contact disruption can be excessive sparking
  • Carbon deposits on copper fins. It is recommended that the surface of the copper fins be periodically or regularly cleaned of carbon deposits. Fouling is usually caused by worn brushes, so if you see blackening on the surface of the collector, you should wipe it down with alcohol

Masters often observe the phenomenon of excessive sparking after they change the brushes on the angle grinder. Based on the factors described above, you can identify the cause, and eliminate it before the tool fails. The elements under consideration are inexpensive, but because of their improper selection and use, the power tool can break. To find out what fault is the cause of the strong sparking, you need to disassemble the power tool, and make its inspection, as well as to test the rotor winding.

Why do the brushes spark in the motor, what this phenomenon leads to and how you can eliminate it.

Subject: What to do if the brushes in an electric motor are excessively sparking.

So, initially, I will say that the very sparking when working collector electric machines. it’s normal, but it should be very small, barely visible to the eye. It is abnormal when a motor is running and sparks are flying out of its brushes. that’s bad. The very phenomenon of spark formation is due to the intermittent electrical contact that occurs during the rotation of the armature, at the moment of the mechanical transition of the brush from one contact, on the collector, to another. At this point the circuit is interrupted and the current flowing in the armature coils ends with a spark, a small arc discharge. Consequently, the greater the power and current in the circuit, the more noticeable will be the sparks. But there are also other factors that contribute to the increase of the spark.

Also pay attention to the condition of the gaps between the contacts on the collector. It is often the case that they are clogged with graphite dust, which is a conductor of a certain resistance

Naturally, if these gaps are dirty, you also clean them (using a pointed tool). Do not forget to check the condition of the brushes, their wear, the clamping force, the freedom of vertical movement. If you find problems with the brushes, be sure to fix them. Note that when replacing the graphite brushes you must take into account that they come in all sorts of colors. In this case try to find exactly the same type as the old ones.

Check the armature should be checked in an alternating electromagnetic field. If there are shorted windings then the armature will rattle in such a field as induced currents begin to form in it. To do this, you can make a homemade device from a power transformer, preliminarily on its core made wedge-shaped cutout, which must be inserted into the armature for testing.

Since this is important, I’ll repeat once again. increased spark formation during the operation of the electric motor affects its duration of operation. In this case, heavy soot will quickly appear on the collector contacts, which after a while will put the electrical equipment out of order

It is better to remove sparks at once than to have to replace the whole armature later on.

Angle grinder sparking armature repair | sparking commutator damaged power tools

Reasons why the brushes are sparking

It is very common to see brushes sparking on an angle grinder. There is evidence of arcing through the ventilation holes in the power tool’s body. Masters wonder why the brushes on the angle grinder spark, even after replacing them directly. There are many reasons for this, and to understand it, you need to have an understanding of the device of the power tool. If you know how an angle grinder is arranged inside, then it is not very difficult to understand why the brushes spark strongly.

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The following are the causes of severe brush arcing on bolsters:

  • Armature Winding Faults. If there is a violation of the insulation of the armature winding, it eventually contributes to the development of an inter-turn short circuit, as well as a short circuit on the core. In addition, there can be a breakage of the winding, which will eventually cause an increase in the load. A hallmark of armature winding failure is a decrease in speed, increased noise and a drop in power
  • Brushes are not pressed well on the collector. The main part is clamped by a spring, which loses its original springing properties over time
  • The rotor winding has broken away from the copper collector plate. this is very rare, but if the power tool is overloaded, it could very well happen
  • The motor armature becomes misaligned and excessive brush arcing on the angle grinder is the result
  • The shape of the collector is broken. The manifold, consisting of copper lamellas, has a cylindrical shape which may be disturbed when the rotor is rewound. The slightest deformation of the shape of the collector will cause the brushes to spark
  • Insulation between the collector blades is broken. Each plate of the collector is insulated between each other, and if the micanite insulation layer is broken, arcing occurs. Insulation between the plates can be broken also because of the settling of the graphite layer in the grooves
  • When the armature bearings are worn. If the bearings are faulty then the rotating armature will run out and consequently show signs of arcing
  • Warping of the rotor shaft. It is difficult to bend it, but if it does, it makes the motor run under load. To prevent tool failure, it is recommended that the rotor be replaced
  • If the armature winding ends are incorrectly brazed to the copper collector plates. Such mistakes are not made in the factory, but they can be made by the winder who rewinds the armature of an electric tool
  • Unsuitable composition of the graphite brushes. The parts in question are made from carbon and graphite, adding different types of impurities. This is done for a reason, but in order to use the brushes depending on the voltage and speed of the shaft. Graphite is either soft or hard. The lower the supply voltage, the softer the graphite grade is selected. For high-voltage power tools, it is necessary to use rigid brushes that do not contain copper
  • Deformation of the lamellae due to heat. If the angle grinder is overloaded, one or more of the collector lamellae may become deformed. The plates are lifted relative to the others, and as a result the contact is disturbed. This condition causes excessive brush arcing when the power tool is operating
  • Poor contact at brush connection. If the terminal is loosely connected to the device, then the result of such a violation of contact can manifest itself as excessive sparking
  • Carbon deposits on copper fins. Periodic or regular cleaning of the surface of the copper fins is recommended. Fouling is usually caused by worn brushes, so if you find blackening on the surface of the manifold, wipe it down with alcohol

Often craftsmen after changing the brushes on an angle grinder, observe the phenomenon of excessive sparking. Based on the factors described above, you can identify the cause, and eliminate it before the tool fails. These elements are inexpensive, but because of their improper selection and use, the power tool can break down. To find out what fault is causing the severe sparking, you’ll need to disassemble the power tool and inspect it and test the rotor winding.

Brushes spark on the angle grinder What’s the problem

Checking and repairing the anchor angle grinder at home

As Shakespeare said, “Nothing lasts forever beneath the moon. Home appliances, as unfortunate as it may sound, are no exception. It happens that the most reliable mechanism burns out.

And you need to prepare to meet this fact without panic, with the firm belief that there is no hopeless situation.

How is the angle grinder, what are the faults, how to check the motor armature, to find the cause of failure and remove problems? Knowledge of the device the main units of power tools will allow the master himself to make diagnostics and repair the angle grinder.

Features of the asynchronous motor angle grinder

In fact, in many appliances used in the home, is used asynchronous electronic motor. The fundamental advantage of this type of motor is that when you change the load there, the speed does not change.

This means that if, for example, a long time and without stopping to cut stone with a household angle grinder, no outward signs of motor overload noticeable will not be. The speed of rotation of the disc will be unchanged, the sound will be monotonous.

Only the temperature will change, but this is an option and not even visible if your hands are wearing gloves.

With inattention, which have the game slots turns into a disadvantage. Induction motors are very sensitive to overheating, a significant excess of operating temperature leads to melting of the insulation on the windings of the rotor.

At first, the motor runs intermittently, and then. when an intercircuiting pile-up occurs. the motor will stop completely. It is worth a couple of times to very overheat the engine angle grinder and, more likely, that the anchor will melt.

Already today, from the highest temperature solder off the contacts that connect the wires of the primary winding to the collector, which leads to an interruption of the electronic current.

How to find the angle grinder armature malfunction

Signs of breakage angle grinder anchor are: over-sparking brushes on the motor collector, the vibration of the motor at low speeds, the rotation of the working shaft in different directions. If such symptoms are found, work with the tool must be terminated. it is not safe. Suspicions are simple to check with light tests.

Visual inspection from the outside

Start troubleshooting with a visual inspection of the angle grinder:

  • Conduct a general inspection of the tool.
  • Examine the integrity of the power cord, the presence of voltage in the socket.
  • Use a voltage indicator to make sure that current is flowing to the collector of the motor and the start button.

Inspect the unit from the inside

If everything is okay with the power supply, but the angle grinder does not work, you have to open up the housing to get access to the motor. Disassembly is usually not difficult. However, you need to adhere to the usual rules that will avoid problems at the time of reassembly:

  • Always unplug the unit before disassembling it.
  • Remove the blade and protective cover from the spindle.
  • Open the enclosure in a well-lit place, on an untainted table surface.
  • To understand the placement of all parts and assemblies before disassembly. It is recommended that you draw or photograph the layout of the apparatus.
  • Self-tapping screws and fastening screws should be kept in a separate place so they do not get lost.

Examine the motor much more reliably under a catchy light, so that our customer remains small parts perfectly distinguishable. Anchor should rotate freely around its own axis, properly working bearings must not be during the operation of the sound.

There is no sign of melted wiring on the armature, and the windings need to be intact, with no breaks. Certainly smell the rotor. If there is a short circuit, the armature insulating varnish will burn and give off a peculiar and persistent smell. Alas, this diagnosis requires a certain amount of experience.

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Testing the circuits with a tester

If the visual inspection does not give obvious results, it is advisable to continue the examination with a multimeter.

With the mode selector in the ohmmeter position (200 ohm spectrum) use 2 feelers to probe the two adjacent armature lamellae. If the resistance on all windings is uniform, it means that the windings are serviceable.

When any pair of the tester indicates a different resistance or an open circuit, that coil is at fault.

Sometimes wire breaks occur between the coil and the core. Carefully examine the connection points between the coils and the collector blades at the bottom of the armature, visually check the soldering of the contacts.

Angle grinder sparks on brushes, repair

In this video we examined the widespread failure of this model of angle grinder, the stator failed, as.

Brushes on angle grinder are sparking?

If there is no tester, get out of the situation of course with the help of an ordinary 12 volt light bulb. The power may be any, normally 30-40 watts.

angle, grinder, armature, sparks

The voltage from the 12 volt battery to supply the plug of the angle grinder, by inserting the light bulb in the gap of the textbook wire. If the armature is functioning, if you turn the spindle by hand, the bulb should glow, without changing the brightness.

If the filament changes, it is a sure sign of an inter-turn short circuit.

On the contrary, the light bulb does not light up, it indicates the following:

  • It may be that the brushes are hanging in a non-working position. The retaining spring has worked.
  • Power circuit interruption occurred.
  • A short circuit, as it is also called a break in the stator winding.

There are other methods of diagnosis, but they require more sophisticated equipment, which are usually not used on their own. The most experienced master will determine the breakage with the highest degree of accuracy, using a “puncher” or otherwise speaking a simple transformer with a cut toroidal core and one primary winding.

Where of course to salvage the armature and return it to the home

If the damage to the armature is ascertained with certainty, the part must be removed from the motor. The dismantling of the motor must be done with great care, having previously removed the brushes and disconnected the power terminals. The rotor is taken out along with the support bearings and the motor cooling impeller, they form one unit with it.

Grinding with an emery cloth

The armature shaft is fixed in the chuck of some torsion machine (lathe, drill). Starts the rotation, the abrasive is applied to the collector. Avoid forceful pushing and the use of coarse sandpaper. A minimum grit value of 1000 P.

Use multimeter to detect if there is a breakdown in the armature winding. Set resistance test mode. Place one feeler gauge on the lamella and the other on the contact of the corresponding coil trace. No open circuit will be indicated by an audible signal. If there is no signal, then the line is broken. Armature replacement or rewinding is necessary.

angle, grinder, armature, sparks

Detect the presence of runout in the bearings. If it is found, replace the bearings and measure the diameter of the armature shaft edges where it adjoins the assemblies with a micrometer.

Integrity of rotor and stator windings

serious arcing problems are short circuits in the rotor or stator windings. It is difficult to correct such a breakage by yourself. Signs of a winding problem:

  • Blackening is observed on the collector lamellae;
  • Sparks are flying in circles;
  • The speed of the motor has decreased.
  • The operation of the motor is accompanied by applause;

Advice! If after a visual inspection it is not possible to find where the winding is damaged, you can resort to electrical measurements with a multimeter.

Experienced electricians have no trouble figuring out how to perform electrical measurements:

  • between the stator housing and the winding terminal;
  • between the collector and the rotor housing (armature);
  • stator winding ring for continuity.
  • to the connected winding leads on the collector plates;

Important! Resistance and voltage measurements will help determine the failed motor component. A vacuum cleaner with a defective motor winding cannot be used.

angle, grinder, armature, sparks

It is very problematic for home masters without special equipment to rewind the faulty element of the electric motor. Contact a professional electrician. If you contact a service center, for example, with a Samsung vacuum cleaner, you may be offered to replace the stator winding or buy a new motor.

Degree of sparking

Quality of commutation, according to GOST 183-74 (Table 1), estimated by the degree of arcing (commutation class) under the runaway edge of the brush, ie under the edge from which the plates of the collector emerge at their rotation. The degree of sparking is 1, 1¼ and 1½ and is admissible in all operating conditions.

Degree of arcing (switching class) of electrical machines

Slight spot sparking under a small portion of the brushes

No blackening on collector and no carbon deposits on brushes

Why do electric motor brushes spark?

Collector motors differ from other motor types in that they have a collector-brush unit. The assembly provides the electrical connection between the rotor circuit and the circuits located in the stationary part of the motor and includes the collector (a set of contacts located directly on the rotor) and the brushes (sliding contacts located outside the rotor and pressed against the collector).

When a collector motor is running in a power tool, you can sometimes see brushes sparking. In some cases, this symptom will lead to an early breakdown of the power tool, and in some cases it does not bode ill. In any case, it is useful in each case to understand the causes of arcing so that the correct measures can be taken in good time if necessary. In this article we will look at the causes of brush arcing, and measures to combat the problems that cause it.

Obviously, the intermittent mechanical contact between the brushes and the collector cannot help but cause arcing, because essentially the electrical circuit of the rotor breaks and closes again many times per second.

The rotor has a winding that is predominantly an inductive load. The breaking of such a circuit is inevitably accompanied by a transient process associated with the occurrence 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 well as the collector plates, but sometimes problems arise even before the moment of wear.

For the sake of justice, note that for the above-mentioned reason, even a faultless collector motor cannot work at all without sparks, there is always a small sparking on the collector. A fully functional appliance goes to full power normally, develops working speed and still sparks a little. It is quite another matter, if the sparking is strong. there is a reasonable concern.

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

How to check that this is the case? If you press the worn brushes to the collector with a screwdriver, the contact will become tight and the engine will start. But as soon as you loosen the pressure, the sparks will appear again. the distance between the plates and the brushes will be filled with small arcs. The brushes are visibly worn. they must be replaced with new ones. Sometimes the armature can only be replaced all together. with brush holders and springs.

There may be a short circuit in the rotor winding

The armature (rotor) winding of a collector motor traditionally contains several sections. If at least one is damaged, if there is an inter-turn fault, then one section will draw more current than the others. This will cause the winding to overheat in one place, and will cause uneven sparks on the collector. some plate transitions will have stronger sparks than others. This requires the armature to be rewound or a whole new armature.

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A similar fault is possible inside the stator, when part of the winding overheats and there is heavy sparking near one of the brushes. Check winding resistance of both halves of the stator winding, they must be identical. If one part of the stator winding has a much lower resistance than the other, it is necessary to rewind or replace the stator.

A dirty manifold is the cause of unnecessary shorting on the manifold, resulting in unnecessary sparks

Dust on the collector is a result of the gradual wear of the brushes. this is graphite dust. It builds up between the plates (blades) on the collector and creates “unauthorized” short circuits. Short circuits cause sparks. Simply clean the collector with sandpaper and remove the dirt between the lamellae.

Always check the alignment of the brushes to see if one of them is misaligned with the other, and correct them if necessary. When the brushes are misaligned, graphite dust is produced in disproportionately large quantities than when the brushes are properly aligned.

Another cause of fouling is fouling of the manifold due to overheating of the manifold. When all other causes of arcing are eliminated, clean the contacts of carbon deposits to improve brush to brush contact.

If the contact is good, the resistance does not increase beyond the nominal, and no unnecessary sparks occur. You can clean off the carbon deposits like graphite dust with sandpaper, but only by rotating the rotor with the collector clamped in special pads.

Characteristics and action of angle grinder brushes

the angle grinder is one of the most popular power tools. Many people believe that the drill is in first place, and the angle grinder in second place. It is so popular because of its versatility, because it can perform a variety of works.

It is both metal cutting, and scraping and grinding, and you can cut not only metal, but also tiles, wood, porcelain tiles and more, depending on the nozzles and imagination of masters on the adaptation of the tool.

The new angle grinder works great and copes with most tasks, but there comes a time when the machine fails. the brushes wear out or “burn out”.

Action and features

These elements are needed for the normal operation of not only the angle grinder, but also many other power tools. Graphite brushes for angle grinders are needed to remove voltage from the stator, while allowing electricity to flow and driving the moving mechanism. They are subject to wear because of friction against the armature collector which rotates during operation.

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It is very important to change the brushes at the right time, because otherwise the power tool can be destroyed.

When the brushes are in good condition, the rotating parts move without difficulty or difficulty. In order not to miss the wear of the brushes, it is necessary to periodically check their performance.

If the graphite rod has worn down and the edge is near the wear limiters, it must be replaced.

These parts also reduce tool wear and tear because they are so easy to replace. It is essential that the brushes can withstand the mechanical stress caused by the rotation of the rotor.

Materials for manufacturing

Various materials are used for the brushes, but carbon or graphite are the most frequently used. Less commonly used are carbon-graphite, copper-carbon, copper-plated.

Graphite brushes for angle grinders are well suited because of their high conductivity and generally good commutation properties. Some types of this part can automatically move away from the rotor in the event of overloading and not be damaged, which is achieved by a ceramic spring tip that is embedded in the body of the part spring.

The ceramic tip does not conduct current and releases when the brush wears out, causing the spring to push out the connector. Carbon brushes for angle grinders are more wear-resistant.

Even in tools with reverse rotation, such as drills and impact wrenches, they are durable and retain their power in reverse operation. Particular attention must be paid to parts with extra contact.

The manufacturer of such a tool guarantees trouble-free operation only if the brushes are replaced with original ones.

Reasons for rapid wear and tear

Very often those who use an angle grinder, wonder why the brushes on the angle grinder burn. However, the angle grinder itself has nothing to do with it, because this phenomenon can happen with any motor of the collector type.

Collector motor speeds are not limited by current frequency, and due to the increased speeds, the collector must be able to withstand the load, and the sparking under the brushes must be reduced without heating the motor.

If there are problems in the power tool, there is a sparking of brushes.

There may be many reasons for this phenomenon. These are:

  • Faulty armature winding. Windings short circuited, sections of winding interrupted. The motor may then become very noisy or lose speed.
  • Poor contact or complete winding failure on the collector plates.
  • Wear of the compression springs, as a result of which the brushes do not press against the collector. Most often caused by prolonged use and overheating.
  • Armature misalignment.
  • Bearing wear and rotor run-out.
  • Breaking of the armature geometry due to “hard” disassembly of the motor.
  • Brushes out of polarity with respect to the collector.
  • The installed brushes are not suitable for the motor.

Arcing of the brushes on the angle grinder can also be caused by the elevation of one or more plates on the collector as a result of overheating. If the polarity of the brushes is incorrect in relation to the collector, the brushes will become very arcing and wear out very quickly. Sparking is, of course, when the armature is rotating, but if this phenomenon is excessive and there is a smell of burning from the air hole, the graphite or carbon part must be immediately replaced.

angle, grinder, armature, sparks

Brush changing methods

If the stator and rotor winding has not yet burned out, then you need to deal with the technical options for replacement, and there are several of these:

  • Angle grinder model is equipped with small plastic caps with threaded or fastened screws. These covers are simply unscrewed and the part is replaced.
  • The angle grinder has a brush holder which is hidden under the housing. To replace the consumable, you need to disassemble the housing by unscrewing a few screws. Such a tool usually consists of two parts, in one of which you can find the trigger and brush holders when disassembling. Brush holders may differ in design. In the hinged holder it is necessary to disconnect the electrical circuit and then insert a new part, while in the conventional holder this action is not always necessary. depending on the design.

After disassembly, it is desirable to clean the grinder from dust and the presence of foreign matter. It is also necessary to inspect the manifold for scratches and damage, as worn parts may have affected the integrity of its surface.

Types of faults

These replaceable and relatively inexpensive parts can also have malfunctions:

This results in more sparks. To fix it, they are lapped with glass paper. During the lapping process, first use a coarse-grained material, then a fine grained one. The use of an emery cloth is undesirable in this case, because emery dust on the collector can short-circuit the collector plates.

Problem solutions

In most cases, a short circuit in the stator or rotor can be the reason why the brushes burn.