Professionals can easily determine the quality of the grinder, the compliance of its technical characteristics with the planned work. But, in the case of an incorrectly selected tool, it is difficult for employees to perform the assigned tasks, maintenance costs increase and the risk of injury increases. To avoid operational problems, in this article we will consider the most serious mistakes when choosing an angle grinder.
The torque transmitted to the working body depends on the power of the grinder. This parameter is determined by the size and type of the electric motor, the number of turns and directly affects the cost of the device. With an increase in power, the productivity of the angle grinder also increases, but this increases both the weight and the price of the grinder.
At the same time, lack of power will cause the disc to jam or be unable to handle hard, thick-walled materials. Large and heavy discs are not suitable for low-power models, since the engine will not be able to rotate them at their rated speed. This will lead to an increase in operating currents in the armature windings and overheating of the electrical machine.
Therefore, when choosing an angle grinder in terms of power, one should proceed from the following principles:
Models with power from 500 to 1000 W are used for polishing and grinding wood, metal and concrete surfaces. They will perfectly cope with short-term cutting work around the house. Suitable for cutting tiles, drywall, thin metal.
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Grinders with power from 1000 to 2000 W cope with continuous work on an industrial scale. Suitable for both repairs and capital construction. This category of tool normally copes with cutting fittings, pipes, metal profiles.
Power from 2000 W and more will allow you to carry out heavy work on cutting concrete and reinforced concrete structures, trimming porcelain stoneware. Ideal for construction and capital construction, long-term tasks during a work shift.
It should be noted that low-power grinders cannot be equipped with heavy attachments. For models up to 1000 W, diamond cups or twisted cord brushes are not suitable.
But the excess power of the angle grinder will lead to surface damage during grinding, sharp jerks along the material being processed. As a result, irregularities and beveled edges can occur.
Angle grinders are equipped with a protective cover that limits the maximum diameter of the disc to be fitted. If the protective cover is removed and accessories larger than the nominal size are installed, a dangerous mode of operation will occur. The angular acceleration of the disc edge will reach too high a value, which will threaten the destruction of the working element and injury to the worker.
Grinder disc diameter
In the case of using discs with a smaller diameter than the design of the angle grinder provides, the working body will not reach the nominal working speed. As a result, performance will decrease proportionally. Therefore, for each standard size of disks, a specific type of work is provided that can be performed by it:
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Disk rotation speed
For each standard size of the disc and type of work, restrictions on the rotation speed are set. The larger the diameter of the working body, the greater the circular speed the extreme point on it will move. In the case of an incorrectly selected disc and grinder, the tool will become ineffective or may fly apart during work. Therefore, angle grinders, according to the disc diameter, can be operated at the following speeds:
115, 125mm has a maximum rotation speed in the range of 10,000 – 15,000 rpm;
150, 180mm are limited to rotation speed of 8,500 rpm;
230mm can rotate at 6,500 rpm.
Permissible rotational speed of the grinder disk
In addition to limiting the spindle rotation speed depending on the disc size, there are recommended rotation speeds in accordance with the type of work performed and the type of surface to be processed:
To polish a car or marble surface, use a speed of 2800 rpm;
It is better to cut non-ferrous metals at a speed of 6000 rpm;
Cleaning metal surfaces from rust, cutting artificial stone at a speed of 11,000 – 13,000 rpm;
Cutting tiles and tiles, grinding stone should be carried out at a speed of 6000 – 8000 rpm;
Glass cutting is carried out at a speed of 10,000 rpm, but requires certain skills and dexterity.
If you do not know what kind of work the grinder will be used for and want to provide for the possibility of performing various types of cutting and grinding, choose a model with a rotational speed adjustment function.
The protective cover of the angle grinder prevents the particles of the processed material from bouncing onto the operator. Most grinders can change the angle of rotation of the screen to release the corresponding section of the working disc. The most convenient are the models with push-button adjustment, for which it is enough to hold down the button in the inoperative state and move the casing. In other angle grinders, the protective screen is rotated by disassembling the corresponding unit.
installation of replaceable casings for angle grinders
In addition, a number of special-purpose casings can be purchased for angle grinders: for the development of strobes for wiring or for grinding with the ability to remove dust. Special covers are installed instead of the standard one and allow you to connect an industrial vacuum cleaner to the branch pipe. Thanks to this solution, all dust will not enter the room, which will preserve health and increase productivity.
But, the proprietary protective casing mounts do not allow the installation of other auxiliary equipment. Therefore, in order to be able to replace and install new elements, you should choose a grinder with a unified type of attachment.
Long-term work on massive hard surfaces requires serious physical efforts from the angle grinder operator. Sawing or turning certain materials creates a strong vibration through the body, which is transmitted to the hands. When choosing a grinder with a conventional handle, the operator will quickly get tired, the accuracy of fixing the tool and the quality of work will be violated.
Therefore, for grinding and cutting work, where strong vibration is expected, a tool with a vibration damper in the handle is selected.
additional grinder handle: standard and with vibration damper
It should be noted that in some models the vibration damper is installed in both the main and additional handles.
In most angle grinders, the additional handle is removable, which allows you to change the position of the hands. This function is represented by both fixed threaded holes and a movable yoke that surrounds the body in a circle.
It is worth noting that fixing the additional handle in a stationary hole is much stronger and more reliable. But it provides opportunities for only a few hand positions and implements a pair of grips. Clamping the handle provides more hand positions and allows you to handle irregularly shaped structures and work in hard-to-reach places. However, with prolonged heavy work, the clamp will gradually weaken, which can affect the quality of the cut or sanding.
Dust protection for the engine
Choosing a grinder for grinding stone and concrete surfaces, sawing wood, MDF, chipboard and other materials, a model with protection against dust must be selected. This function is implemented as filling the motor windings with resin, installing an impeller that throws large pieces of debris to the walls of the housing. The lack of such protection is fraught with rapid clogging of the shaft and windings, which will lead to premature failure of the grinder.
When performing a large amount of locksmith and construction work, the angle grinder operator can often change discs to perform various operations on the site. Even at home, when sawing wood structures, it may be necessary to quickly replace a disc for wood with a disc for metal.