Brushes are called as current collectors inside an angle grinder. a necessary element of an electric motor, without which an angle grinder, like any other electric tool, will not be able to work, and removable nozzles that allow using this tool to clean, grind and even polish various surfaces. In this article, we will try to deal with those and other brushes.
If we talk about electrobrushes, then first you need to clarify the name. This device was called brushes even in the initial times of its existence (the beginning of the 20th century), when, in fact, to remove the current from the rotor of the electric motor, a design resembling a brush or, more precisely, a brush was used. Such a device, despite its high efficiency, turned out to be too short-lived and was replaced by a stronger one, made of dense material, into which a copper wire is pressed.
The movement of the rotor of the electric motor causes constant friction of the working surface of the electric brushes, which is the main reason for the failure of this part. As a result, they have to be changed periodically. This process is natural and inevitable with prolonged use of any power tool. It is very easy to detect brush wear: a previously reliable unit will begin to work intermittently, a characteristic odor of ozone from the abundant sparking in the current collector may appear. It is advisable to replace the electric brushes at the first sign of abrasion.
Electric brushes are graphite, coal or metallographic. In all varieties, the main material is carbon.
In the first case, the product is pressed at high pressure, and then thermally processed, gaining increased wear resistance. The coal version is the cheapest, since it does not involve heat treatment. Such brushes are the least durable. Metallographite brushes are the most expensive since, in addition to carbon, they contain metal powder. This is the most wear-resistant option, which is very rare in household appliances. As already mentioned, also called a brush removable nozzle for an angle grinder.
To UMSh (angle grinder) to perform its main functions, it is necessary to install one or another nozzle on it. It can be cutting or grinding disks or brushes with various kinds of pile fixed in a circle. Such a removable device is called a cord brush or, even shorter, a brush. Brushes, like disks for UMSh, are consumables. In the process, they wear out and need to be changed. The brushes for the angle grinder are arranged in such a way that they are mounted on the rod thanks to the hole in the center, this is their main difference from the brushes for the drill, which have a shank for installing them in the drill chuck.
Brush pile, depending on the specifics of its application, can be steel, brass, made of polymer fibers and even wool.
What are they for?
In this section we won’t talk about electric brushes for a long time, their purpose is to remove current from the rotor (anchor), in other words, without them there will be no rotation in the electric motor, the electric tool rod will not rotate, and it will not work. But the cord brushes need to be said in more detail. They are used for machining various materials. Different types of these nozzles are used for cleaning before painting or applying soil, for brushing wood, for removing old paint from various surfaces, for polishing, grinding, smoothing corners and other operations.
They are especially necessary for cleaning metal products after welding to remove scale.
As already mentioned, electrobrushes can be classified by the material from which they are made. The graphite brush, as the name implies, is made of graphite, in which soot and binders are added. This type of current collectors is most often used for UMSh.
The carbon brush is made of the same material, but without heat treatment. Such a product is abraded much faster and is practically not used for an angle grinder. It is important not to make a mistake when purchasing replacement brushes. Carbon brushes on the angle grinder will not last long.
Video: What You Need To Brush In An Angle Grinder
The metal-graphite brush is used in large industrial units, and it is unlikely to be able to install it on an angle grinder. This is the most durable product with a very high price. The variety of cord brushes is much larger, their shape, material and size vary significantly, which is determined by the variety of applications of such equipment. They can also be classified by the material from which they are made. The most popular are brushes with metal pile. The metal brush is a fairly versatile nozzle. For the manufacture of such products, both metals and alloys are used.
To work on metal, steel brushes are used. Stainless steel brushes are best used on stainless steel or aluminum. Often, steel pile is coated with brass, such brushes are not subject to corrosion. There are also pure brass brushes. in spite of their great softness, they have several advantages: a relatively soft effect on the material, the absence of sparks when working at high speeds, and the absence of scratches during surface treatment.
The wire for such brushes may be different. The twisted wire is usually the most rigid, it can be assembled with bundles (they are more rigid and can self-sharpen) or fixed randomly. With such effective nozzles, you can strip off the scale from welding or rust. The corrugated cord brush has a wave-like curved pile and, unlike the previous type, acts on the surface not so intensively. With its help, you can clean the surface of old paint.
Flat bristles are widely used, they are the most versatile and can be used on any surface. Their effectiveness may be slightly lower than that of specialized nozzles. Nozzles with polymer nap, for example, nylon, are used for polishing various surfaces, including metal. You can successfully use them for woodwork. to highlight the texture or final processing. Plastic brushes are often used to work with soft materials.
Brushes can be divided in shape.
Cup is used to work with large surfaces. Its form follows from the name. On such a brush, the clamping nut is most often immediately fixed, since the special key provided with the angle grinder cannot be applied to it. The conical brush is used to work with concave surfaces. Radial, as a kind of flat brushes, is used to treat hard-to-reach areas. The disk, the most common type of cord brush, also has a flat shape and can be used to process a wide variety of small surface areas.
And cord brushes are divided into size groups. The diameter of the brushes is determined by the technical capabilities of the angle grinder and the scope of this nozzle. Brushes with a diameter of less than 115 mm are usually used for processing small surfaces. A circle of more than 200 mm for a small angle grinder is better not to use, you will have to remove the protective cover, and this is a violation of all safety standards. Such large brushes are usually used for processing large-sized structures and only with the help of large powerful UMSH.
The most suitable for domestic use is a diameter of 125 mm brushes. You can offer a fourth classification of cord brushes. by application. Brush kratsovka, the name is given from the name of the technical operation that is carried out using this nozzle. Krastovanie. preparation of the surface for subsequent processing: removal of rust, paint, dirt. At some stages, this is a process of chemical exposure to the surface of the product, but the initial processing consists in mechanically cleaning the surface. For mechanical coating, metal (steel or with brass coating) brushes are used. The task of this treatment is to remove scale, oil stains, minor defects, burrs and the like. Without cladding, it is sometimes difficult to evaluate the quality of the weld, adhering mill scale can hide some defects.
For processing soft materials (plastic or wood), nylon, tow (sisal) and hair scrub brushes are used. Such brushes must be moistened with special emulsions (you can use vegetable oil for wood), otherwise the surface will turn dull.
How to choose?
If you have decided on the size and type of brush, you should pay attention to its quality. The wire iron brush should have a uniformly distributed pile, individual fibers should not be longer or shorter, this factor can cause poor-quality surface treatment and excessive vibration, therefore, the load on not only the parts of the angle grinder, but also on the hands of the person who will perform work.
Excessive vibration of the machine during operation is the main reason for the high load on the muscles of the hands. With a small diameter brush, vibration is always less. A polymer brush is the lightest kind of cord brush, and the vibration with it is the smallest, but not every surface can be treated with such a nozzle. A polymer-abrasive brush is used for brushing (aging) wood, and you should not try to process metal with it.