Why Brushes Are Quickly Erased On An Angle Grinder

What is it?

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

A copper wire without a 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 the spring, which rests with one edge against the brush, and the other against this plate. The spring has a free pressing action and the brush fits snugly against the collector as it rotates.

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

Sandpaper groove

The armature shaft is fixed in the chuck of any torque mechanism (lathe, drill). Rotation starts, the abrasive is applied to the collector. Forceful pressing and the use of coarse-grained sandpaper are excluded. The minimum grit value is 1000 P.

Using a multimeter, detect the presence of a breakdown in the armature winding. Set resistance test mode. Attach one probe to the lamella and the other to the contact of the corresponding winding path. The absence of an open circuit will be indicated by an audible signal. If there is a signal, this trace is broken. You will need to replace the armature or rewind its winding.

Determine if the bearings are running out. If it is found, replace the bearings and measure the diameter of the armature shaft edges with a micrometer in the places where it is adjacent to the assembly units.

How to troubleshoot?

Examined the collector for mechanical damage. If dust, dirt, sand gets on it at the time of work, scratches, dents, chips may form. Assess their degree, if any.

The reasons

There may be several reasons why brushes on an angle grinder sparkle and wear out strongly:

  • Malfunction or increased wear of the brushes themselves;
  • Violation of the density of contact between them and the collector plates;
  • Deterioration of the clamping action of the brush spring;
  • Breakdown between collector lamellas;
  • Axial runout of the armature due to bearing wear;
  • Short circuit in the armature winding;
  • Introduction of structural damage to the mechanism during repair.

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

In order to avoid the appearance of a spark in the area of ​​\ u200b \ u200bbrushes, you should follow the rules for the safe use of an angle grinder.

  • Will not turn on in case of high humidity, pronounced voltage drops in the network, dirt entering the brush block, contamination of the air duct grilles in the housing.
  • Inadmissibility of engine overheating, load, slowing down the rotation of the mechanism at the time of operation.
  • DO NOT use a low-power angle grinder to cut “heavy” materials.

The essence of the problem

Brush arcing makes it impossible for the power tool to operate at full power. Since they are the connecting link in the electrical circuit, disruption of their operation leads to interruptions in the supply of current. This negatively affects the motor winding and reduces its service life.

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

Angle grinder brushes malfunctions and their elimination

The angle grinder is a high-speed electric tool equipped with a collector motor. In this engine, the current is supplied to the armature. the inner rotating part. Such feeding is carried out by a sliding method, and the only way to make contact between the power source and the moving part is with graphite “brushes”. They are the “fuse” against overvoltage and fail first.

Prevention

The angle grinder brushes can be prevented from sparking by taking preventive measures:

  • Observe the operating rules;
  • Regularly change the lubricant in the gearbox and bearing sections, reducing mechanical and thermal loads (factory grease must be replaced at the beginning of any work);
  • Replace bearings in a timely manner, while maintaining the structural integrity of the armature shaft;
  • Install a new set of brushes to the way the old ones start Spark.

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

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

Causes of wear of current collectors

The angle grinder, like most power tools, was originally designed to operate on a DC power source. Then, he switched on the rotor and stator windings in series, it became possible to be powered from alternating current without limiting the number of revolutions, as happens with brushless motors. Therefore, increased requirements are imposed on the unit with a pantograph. And if the brushes on the angle grinder are on, the reason may be the following:

  • Rotary winding malfunction: Twisted short circuit, broken coils. This is characterized by reduced revs and loud humming.
  • An equivalent reason is poor contact between the lamellas and the winding.
  • The springs of the brush holder mechanism are loose.
  • Armature runout due to bearing failure.
  • Reservoir production.
  • Tracks between the lamellas clogged with graphite dust or their closure has occurred. They can be cleaned with a saw blade for metal.
  • Deformation of the rotor shaft.
  • As a result of rewinding the armature, the current-carrying coils are reversed.
  • Brushes of the wrong brand.
  • Normal wear of the current collector.
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NOT all of THESE reasons cause brushes to wear off quickly, but none of them can be ruled out.

Why brushes are quickly erased on an angle grinder

Previously, angle grinders for the Soviet Union were made into an angle grinder, hence the common name of the tool. The USSR has not existed for many years, in such devices, whoever produced them, continue to bear this name among users. Like any technically complex product, this tool sooner or later begins to need repair, which most often consists in replacing brushes for an angle grinder.

The essence of the problem

Brush arcing makes it impossible for the power tool to operate at full power. Since they are the connecting link in the electrical circuit, disruption of their operation leads to interruptions in the supply of current. This negatively affects the motor winding and reduces its service life.

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

Varieties of devices for taking current

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

First you need to understand the types of pantographs:

  • The manufacture of graphite brushes for an angle grinder is carried out by mixing a base substance with a binder. As a result of pressing carbonaceous materials under pressure and further firing, a product with additional strength and wear resistance is obtained. Then the graphitization process begins, which consists in 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 the service life partly compensates for it.
  • For the production of carbon brushes for an angle grinder, 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 material for the manufacture of metal-graphite brushes, as the name suggests, includes metal in addition to the main element. This is usually copper powder, but the addition of tin, lead or silver is not excluded. The metal component can go up to 80 percent. Applications for such parts are found primarily in industrial generators and electric motors. For domestic needs, these products are too expensive.

Sandpaper groove

The armature shaft is fixed in the chuck of any torque mechanism (lathe, drill). Rotation starts, the abrasive is applied to the collector. Forceful pressing and the use of coarse-grained sandpaper are excluded. The minimum grit value is 1000 P.

Using a multimeter, detect the presence of a breakdown in the armature winding. Set resistance test mode. Attach one probe to the lamella and the other to the contact of the corresponding winding path. The absence of an open circuit will be indicated by an audible signal. If there is a signal, this trace is broken. You will need to replace the armature or rewind its winding.

Determine if the bearings are running out. If it is found, replace the bearings and measure the diameter of the armature shaft edges with a micrometer in the places where it is adjacent to the assembly units.

What is it?

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

A copper wire without a 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 the spring, which rests with one edge against the brush, and the other against this plate. The spring has a free pressing action and the brush fits snugly against the collector as it rotates.

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

The concept of the brush mechanism

Since contamination of the angle grinder is inevitable, you need to know more about the design of this part. In case of various malfunctions, the largest percentage is detected precisely in this node. In addition, even in a properly functioning tool, unforced wear of the brushes is inevitable, although this happens very rarely.

Replacement methods

After it has been established why the brushes on the angle grinder are burning and the cause of this malfunction has been eliminated, you can start replacing them. There are two options for the process itself:

  • The easiest way to carry out this event is on those models of household electrical tools where there is free access to the brush compartment without disassembling the case. In this case, this can be done quickly: just open the cover, remove the worn part and insert a new one of the appropriate type.
  • However, this method is not always available. In other cases, you will have to disassemble the device. The first step is to remove the cutting disc from the angle grinder and disconnect it from the power supply. Then, in accordance with the annotation, disassemble the tool. It is usually sufficient to gently remove a few screws and split the case in half. Then you need to disconnect the copper contact of the old part and remove it from the seat. When installing a new spare part, you need to firmly connect the leash in place and check that the brush is firmly pressed to the collector by the spring mechanism. It is especially important to make sure that the type of component to be replaced is matched to that used in this angle grinder. If the discrepancy is only in size, the problem is solved with the help of needle files, fine file or sandpaper.

How to troubleshoot?

Examined the collector for mechanical damage. If dust, dirt, sand gets on it at the time of work, scratches, dents, chips may form. Assess their degree, if any.

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7 reasons why electric motor brushes sparkle

In household electrical equipment, collector motors are widely used. Small dimensions, lightness, ease of operation caused their presence in angle grinders, hammer drills, circular saws, 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.

Why Brushes Are Quickly Erased On An Angle Grinder

Short circuit in the armature winding

The consequence of this defect is uneven sparking on the collector. It will be stronger on some plates than on others. Due to the presence of turn-to-turn closure, the current in SEPARATE sections of the rotor winding will be stronger than in others.

Rewinding or replacing the rotor will fix the problem.

Why brushes are quickly erased on an angle grinder?

Wear of brushes

With prolonged use or poor-quality material of the brushes, they cease to tightly press against the collector contacts. Due to poor contact, the engine does NOT rev up or does not start immediately. A worn out brush is easy to identify visually.

To rectify the situation by replacing only the worn out part sometimes fails. The brush holder and spring should be replaced.

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 spark formation process. Preventive work on cleaning the collector with sandpaper and removing dirt between the plates will keep it clean.

Poor contact of the brushes with the collector

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

It is necessary to clean the collector surface with fine-grain emery paper. To increase the stripping effect Use a screwdriver. Clamp the engine rotor into the chuck and at low speeds, sand the carbon off. After that you need to finally polish it on a felt circle.

Incorrectly installed brushes

If the brushes are located abnormally towards the collector surface, significantly more graphite dust is generated during operation. Displaced brushes need to be corrected.

Malfunction in the stator winding

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

Mechanical violations

Mechanical reasons are caused by non-compliance with the requirements of design and technological documentation. Most of the mechanical causes are eliminated by the manifold groove on the lathe. This repair should be carried out by a qualified technician. Here are some types of faults that may indicate a breakdown:

  • The collector surface is uneven;
  • Shaft runout exceeds the value specified in the technical documentation;
  • Separate collector plates are common for all levels;
  • Insulation protrusion (mica)
  • Brushes in 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 manifold;
  • Uneven tension of the springs, as a result of the difference in the pressing force of the brushes.

, Which can help solve your case:

How to repair an angle grinder with your own hands

Unfortunately, sooner or later the entire tool breaks down, but it doesn’t matter. it can be repaired. Now I will tell you how to repair an angle grinder with your own hands.

The first step is to recall in detail the circumstances under which the breakdown occurred. What for? This will help to determine by 50% what exactly is broken or burnt in the instrument. It is one thing if a concrete slab falls on an angle grinder, and it is quite another thing when, at the moment of operation, all the bulbs flashed brightly and then burned out. The difference is obvious?

The electrical part may burn out from overload (hence, overheating) of the tool at the time of operation, from a surge in the supply voltage, from the ingress of conductive liquids, due to prolonged storage in a damp room, pulling out the plug by the power cord, pressing the switch too sharply and forcefully, etc. P.

Mechanics do not like abnormal operating modes, lack of proper lubrication of bearings and gears of the gearbox, ingress of abrasive dust and moisture, falling to the floor during operation, lack of regular maintenance.

Before starting repairs, an angle grinder, you need to thoroughly clean its case with your own hands. they love it, and sometimes they immediately start working. If it doesn’t help, then you will have to disassemble the machine. Unscrew the fixing screws and remove the cover.

Electrical repair of angle grinders

The electrician is to blame when the angle grinder is generally “silent”, or slowly turns the shaft and / or sparks strongly with brushes. The smell of burnt insulation may be felt.

In 90% of cases of “malfunction” of a power tool, to repair it, it is enough just to plug the plug into a known working socket. If everything is in order with the outlet, then first of all you need to consistently check the power cord and the power button.

The malfunction of the engine speed control circuit can be checked by letting the current bypass it with a short piece of wire. Please note that at this moment the motor is rotating at maximum speed, therefore, first of all, make sure that it is rated for mains voltage (220 volts).

The most common malfunctions in which you can still make repairs to the angle grinder with your own hands are open circuits or short-circuited turns in the armature and (or) stator windings. They arise, as a rule, 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 manifold.

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

If the inspection failed to find the Problem spot, then devices are used: a probe, an ohmmeter, a LATR, a choke with a cut “iron”. For advanced repairmen, the PUNS-5 device is produced.

Watch the in the diagnosis of a malfunction when trying to repair an angle grinder with your own hands.

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Method for finding a malfunction of the Latr electric motor

Slowly increasing the voltage at the LATR output to 250V, we determine the nature of the malfunction of the armature and stator windings.

  • Increasing in proportion to the increase in sparking voltage over the entire surface of the brushes. most often interturn closure.
  • At low voltage, the armature tries to rotate in different directions (in different positions). most likely an inter-turn 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 it with the collector.

With an increase in voltage, an abrupt increase in the spark on one brush occurs. a breakdown of the wire insulation in the stator winding.

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

A technique for finding a malfunction of an electric motor with an ohmmeter

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

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

In the repair of an angle grinder with your own hands, in terms of mechanics, it is very well told and shown in the next.

We can summarize all of the above and shown in one phrase: “Do-it-yourself repair of an angle grinder is not so terrible as it is painted” success!

Topic: what to do if there is a strong spark of brushes in an electric motor.

When operating various electrical engineering that has an electric motor containing a collector, it can sometimes be found that when the engine is operating in the area of ​​contact between the brushes and the collector, strong sparking occurs. This phenomenon indicates that the electric motor is working with some deviations from the norm. This very sparking means that in the near future your electric motor will fail. Not many people know what to do with this negative effect, how to remove it, thereby prolonging the performance of their electrical equipment. In this article, we are with you and we will analyze this issue, I understood the Initial causes of sparking.

So, initially I will say that arcing during the operation of collector electric machines is normal, only it should be very small, barely noticeable to the eye. It’s abnormal when the electric motor is running and sparks are pouring out and flying straight from its brushes. that’s bad. The very phenomenon of spark formation is associated with an intermittent electrical contact that occurs during the rotation of the armature, at the time of the mechanical transition of the brush from one contact on the collector to another. At this time, the circuit is broken and the current flowing through the armature coil ends its passage with a spark, a small arc discharge. Consequently, the more power and current in the circuit, the more noticeable the sparks will be. But besides this, there are other factors that contribute to the increase in the spark.

In order to fully answer the question of why the brushes sparkle in the electric motor, we will analyze the main reasons. First, if the collector contacts are dirty, or carbon deposits have formed on them over time, then the amount of spark from this will naturally increase. Poor contact is known to lead to increased resistance at that location. This means that breaking the contact during operation will be accompanied by a stronger electric arc. This leads to a decrease in the power of the electric motor, to its greater heating, to acceleration and an increase in the formation of even more carbon deposits on the collector contacts, which again will lead to motor breakdown. The way out of this situation will be as follows. you disassemble the device, the engine, and with sandpaper (zero) gently clean the contacts, doing the cleaning in the direction of the brushes.

You should also pay attention to the state 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 with a sharpened tool). Do not forget to check the condition of the brushes, their performance, clamping force, freedom of vertical movement. If problems are identified with the brush, be sure to eliminate them. Please note that when replacing graphite brushes, it is worth taking into account that they are different. In this case, try to find exactly the same type as the old.

The spark of the brush, more than normal, can also be due to the formation of short-circuited turns on the armature. Consequently, when such an electric motor is operating on Some of the collector contacts (Which are associated with this damaged winding), an increased current strength will appear, and as a result, an increased spark formation. In this case, it becomes necessary to check the armature for the existence of such short-circuited turns. This should be done in the event that cleaning the collector and checking the brushes did not give a tangible result.

The armature should be checked in a variable electromagnet 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, having previously made a wedge-shaped cutout on its core, in a yak and you need to put an anchor to check.

P.S. Since this is important, I repeat once again. the increased formation of a spark during operation of the electric motor affects its duration of operation. In this case, Strong carbon deposits will quickly appear on the collector contacts, which, after a while, will disable the electrical equipment. It is better to immediately eliminate the sparks than to replace the whole anchor afterwards.