Carbon-graphite brushes used in electric motors. What to do if they spark.

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

It is worth noting right away that the presence of the said sparking during operation is quite acceptable. But only if the sparks are small and not too many. If they are directly spitting, it may indicate a malfunction.

Note that on the new well-functioning power tool brushes can also spark a lot at first, as they need to rub in first. It usually takes 10-15 minutes of work to lapping. If after that all is left as it was, it’s better to take the tool back to the store with a claim.

If your drill is already out of warranty, then you can try to fix it yourself.

But first let’s describe the causes of this phenomenon.

Why do the brushes spark in the motor, what does this phenomenon lead to and how can it be eliminated?

Subject: What to do if the brushes in an electric motor sparks strongly.

So, initially I will say that the sparking during the work of collector electric machines. it is normal, but it should be very small, barely visible to the eye. It’s not normal when an electric motor is running and sparks are flying straight out of its brushes. that’s bad. The very same phenomenon of spark formation is associated with intermittent electrical contact occurring 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 windings ends up as a spark, a small arc discharge. Consequently, the greater the power and current in the circuit, the more noticeable the sparks will be. But besides that there are other factors that contribute to the spark.

You should also pay attention to the condition of the gaps between the contacts on the collector. They are often clogged with graphite dust, which is a conductor with a certain resistance

Naturally, if these gaps are dirty, you should also clean them (using a pointed instrument). Don’t forget to check the brushes, their working-out, contact force, vertical freedom of movement. If there are problems with the brushes, be sure to fix them. Keep in mind 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.

Check the armature 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 the armature. To do this, you can make a home-made device from the power transformer, previously on its core made wedge-shaped cutout, which must be inserted into the armature for testing.

Since this is important, I will reiterate that increased spark formation during motor operation will affect the longevity of the motor. In this case, quickly appear strong soot on the collector contacts, which over time will lead to failure of electrical equipment

It is better to get rid of the sparks straight away than to have to replace the whole armature on top of that.

Poor contact

In most cases the brushes spark if they are not in good contact with the collector. This can happen if you have installed new. For a tighter fit of brushes to the collector, you can use the “sandpaper” null, or just give the vacuum cleaner to work at medium speed for about 20 minutes. It is necessary to check the condition of the bearings, because their wear can cause runout and uneven rotation of the rotor. In the same way insulation protrusions between the plates of the collector, scratches on the surface, various irregularities show themselves. Use abrasive paper for polishing.

Design of the vacuum cleaner collector motor

Brushes should not dangle in the brush holder, but should have some clearance provided by the spring, the condition of which also plays an important role.

If you decide to replace the brushes, make sure you pay attention to how firmly the spring holds them against the collector. Sometimes it is enough to stretch the spring a bit to make the brushes pressed harder.

Tilt angle

If the angle of the brushes is not correct in relation to the stator, arcing may also occur. The correct position is when both brushes are strictly in line with each other, passing through the axis of rotation of the collector. Over time, from the constant vibration, the brush holder can become loose or even mechanically damaged. Carefully inspect the surfaces of the assemblies. Cracked, chipped, or corroded parts should be replaced.

Every manufacturer adds design features to its line of products, and therefore different types of vacuum cleaners have different brush attachment type. However, in general, all models have the same device, and the brush holder is usually screwed on with two screws and allows you to make adjustments.

What to do if the vacuum cleaner has sparking brushes?

In the process of work, the brushes are worn down because of the constant friction. This creates a need for routine replacement. For this purpose, the manufacturer supplies the power tool with a spare set of brushes. In other situations, you can observe the appearance of sparks in the area of the brushes.

How to know when it’s time to change the brushes

Many people change brushes only after they notice that the tool is sparking and smells foul. Even these symptoms do not stop many assembly operators, who continue to use the tool until it no longer starts. When is it necessary to change the carbon brushes, so as not to damage the device of the power tool. There are the following signs for this:

  • Strong arcing. if you see signs of strong arcing, you need to disassemble the tool and inspect the consumables. Sparking. this is the first sign that the consumables need to be replaced
  • The emergence of a smell of burning. if during the work of the tool you can hear the smell of carbon deposits, then it is recommended to disassemble the angle grinder and make a replacement of the graphite brushes
  • If the main part is worn more than 30%-40%. However, it is almost impossible to determine their initial length unless you measure them before installing the elements
  • When signs such as jerking and “growling” of the power tool appear

They are also replaced if they are unevenly worn or of poor quality.

This is of interest! At home angled grinder is not recommended to buy copper-plated brushes, as they will quickly fail the collector armature due to the high copper content in the composition. Copper-plated elements can be used on grinders, which have a special coating on the collector plates.

Preventive maintenance of manifold devices

In order to prolong the life of the armature, and consequently the electric tool itself, you need to follow a few simple rules. These measures are as follows:

  • Do not run the attachment for a long time at low speed and do not allow it to work under considerable load, in particular do not allow the cutting attachment to jam. If the electric motor becomes jammed, a short blocking time is sufficient to burn it out.
  • If it does become jammed, you must loosen it carefully and let it run idle for two minutes. During this time, due to natural cooling, the heated parts will cool down a little.
  • Observe timing of adding or changing lubricants.
  • If you notice vibrations or noises, you must carry out a preventive examination with disassembly of the housing and cleaning of dirt from the collector and the entire space inside.

Any independent work on the repair of power tools, not only angle grinders, it is recommended not to make before the end of the warranty period. Unauthorized tampering with equipment is not encouraged by the manufacturers. Only the brushes can be replaced without opening the housing; for all other cases, it is best to call an authorized service center for assistance.

An angle grinder is a high-speed electric tool with a commutator motor. In this motor, current is supplied to the armature, the internal rotating part. Such feeding is done by the sliding method, and the only way to make contact of the power source with the moving part is by graphite “brushes“. They are “fuses” against overvoltage and are the first to fail.

How to replace by yourself

What could be easier than replacing the brushes on an angle grinder. However, even here there are some nuances, which should be taken into account in order not to spoil the power tool. First of all you need to choose the right consumables. When choosing should be based on the model of the angle grinder, or remove the brushes installed, and take their dimensions. According to these dimensions buy new elements. There is no point in talking about how much such devices cost, because it is a mere trifle.

Once the consumables are purchased, replacement of brushes is performed. In this case, you should first look at the model of the angle grinder. Some manufacturers equip their power tools with special shafts for quick brush changes. They are plastic caps that can be screwed on or off with a screwdriver.

brushes, spark

If it is an angle grinder, which does not have a special shaft for quick replacement of brushes, then you will need to disassemble the housing to get to the consumables. When access to replace the consumables is obtained, further action is taken in the following sequence:

  • Once the brush holder is accessible, disconnect the contact wire
  • Disconnect the contact wire, which is also connected to the brush holder
  • Remove the worn out element
  • Clean the place where the brush is installed, as it must move freely and without jamming
  • Install the new part in the reverse order of its removal
  • Before reinstalling the brush holder, inspect the manifold. If there are signs of fouling, these should be removed
  • In the same way to perform the procedure for replacement on the other side
brushes, spark

Know how to change the brushes on your angle grinder? The more arcing devices on the power tool, the sooner they need to be replaced. When replacing you should also take into account that it is necessary to change the device in pairs, but not one by one.

Summarizing the work done, it is worth noting that the causes of arcing brushes on the angle grinder a lot, and in each case it is necessary to look for your breakdown. If you are unable to determine the cause of the sparking, the tool should be taken to a professional who will identify the fault and correct it. This is better than continuing to work with a faulty tool, which at any time can burn out or short-circuit. Only with the right approach to repair and maintenance of power tools, you can achieve its long-term operation.

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