Why Quickly Erase Brushes On An Angle Grinder

Angle grinder is a high-speed electric tool equipped with a collector electric motor. In this engine, current is supplied to the anchor. the internal rotating part. Such a feed is carried out by the sliding method, and the only way to contact the power source with the moving part is graphite “brushes”. They are “fuses” against voltage overload and fail first.

A sign of their apparent malfunction is a strong spark with the release of sparks through the ventilation grilles, accompanied by a characteristic sound.

What is it?

These components are made by mixing soot substance with graphite and other binders. hardeners. Such a mixture is a good conductor of electric current.

Rectangular brushes are widely used. They may vary in terms of length and width depending on the particular appliance in which they are installed.

A copper wire without winding is mounted in the “body” of each brush, and an individual configuration plate is soldered to the free edge of it. The wire is inside the spring, which abuts with one edge on the brush and the other on this plate. The spring has a free pressing effect, and the brush fits snugly against the collector during its rotation.

In the process, the brushes are erased due to constant friction. This creates the need for their planned replacement. For this, the manufacturer supplies a power tool with a spare set of brushes.

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

The essence of the problem

The sparking of the brushes makes the power tool unable to function at full capacity. Since they are the connecting link in the electric circuit, the violation of their work leads to interruptions in the supply of current. This negatively affects the motor winding and reduces its working life.

Sometimes a malfunction can be contained in the brushes themselves. They quickly burn out due to cracks, chips, scratches, overheating. Changing the old brush kit will solve the problem. If the cause of the sparking is not in the brushes, then the new ones burn the same.

Video: Why Quickly Erase Brushes On An Angle Grinder


There can be several reasons for the brushes on the angle grinder to spark and wear out a lot:

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

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

Why Quickly Erase Brushes On An Angle Grinder

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

  • Do not switch on at high humidity, pronounced voltage drops in the network, dirt entering the brush unit, or contamination of the air ducts in the housing.
  • Avoid overheating of the engine, load, slowing down the rotation of the mechanism at the time of operation.
  • Do not use a low-power angle grinder for sawing “heavy” materials.

How to fix the malfunction?

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

For minor damage, the collector lamellas can be machined with an emery cloth or on a lathe. The groove should be very neat, as any inaccuracies will lead to a greater deterioration in the work of the brushes.

Sanding Groove

An anchor shaft is fixed in the cartridge of some kind of twisting mechanism (lathe, drill). The rotation starts, the abrasive is applied to the collector. Excluded force pressing and the use of coarse sandpaper. The minimum grain size is 1000 P.

Using a multimeter, detect the presence of breakdown in the armature winding. Set the 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 a sound signal. If there is no signal, this route is broken. An armature needs to be replaced or its winding rewound.

Detect runout in bearings. If it is detected, replace the bearings and measure with a micrometer the diameter of the edges of the armature shaft at the points where it adjoins the assembly units.