Cordless wrenches: characteristics, models, tips for choosing

Anyone who has to do repairs at some point comes to the idea that it would be nice to get an electric or cordless wrench. Such a tool is used not only when work is being carried out on the installation / dismantling of a threaded connection, but also where the use of a simple wrench is impossible. These can be hard-to-reach places, rust, low-quality metal, or a nut with non-standard edges. The use of industrial and household appliances when tightening / unscrewing nuts makes repair work more effective and significantly reduces their time.

When the wrench is turned on, power is supplied from the battery to the motor. He transforms it into mechanical energy and transfers it to the gearbox, which makes the chuck work through the shaft. By the type of impact on the nut, nutrunners are divided into impact and non-impact. The impactless impact wrench cannot boast significant torque, but it is easier to use in operations requiring precise use of the device.

Electric motors of impact wrenches are equipped with special impact devices that maximize the torque. They are distinguished by the peculiarity of the effect on the nut: if it is screwed on easily, it is subjected to tightening by long blows, and tightening is done in jerks with increasing force. With the help of such hammers, even the most "stuck" nut is easily broken off, and it is much easier to tighten a large connection. That is, a slightly different principle is applied here: the shaft does not rotate constantly and evenly, but in jerks that act not on screwing in, but to the side. In addition to increasing the efficiency of the tool, it also does not strain the worker's hand muscles.

Typically, nutrunners, like all tools used for mounting / dismounting threaded connections, classified by:

• type of drive (power supply, battery, pneumatic, hydraulic);
• the type of impact on the nut (impulse, shock, non-shock);
• the presence of a reverse;
• the number of additional speeds;
• the number of revolutions;
• torque;
• the type and size of the cartridge;
• dimensions;
• weight.

As with any mechanical device, battery operated impact wrenches have their advantages and disadvantages depending on the model. The benefits include the following:

• autonomous work, limited in time only by the capacity of the battery;
• tool mobility - it is not tied to an outlet due to the limited length of the power cable;
• the tightening torque can be adjusted.

Of the huge number of options that manufacturers of nutrunners offer, you can find models with decent technical characteristics, and tools that are completely unsuitable for long-term operation. Experienced workers recommend paying attention to the following points when buying a wrench.

• The main technical characteristic of the power capabilities of the wrench, which is called the torque / limit / torque. The most affordable models have a torque range of 100 - 300 Nm.For household operations like assembling furniture, it is enough, but for loosening problem nuts, it is recommended to have a device with a torque of up to 500 Nm.

• Battery capacity, which is the most important characteristic for wrenches that are not connected to the mains. The operating time of the wrench directly depends on its capacity and on the power of the electric motor. The most common are removable Ni-Cd and Li-ion batteries with a thousandth charge cycle. A battery charger is always included with each such tool.
• Power Supply. Its voltage can vary between 9-18 volts.

• The weight of the wrench, which also plays an important role. More weight will make the work more efficient, but it will tire the muscles much faster. The weight of light devices is within a kilogram, the weight of more powerful professional wrenches is approximately 3 times more. The faster the spindle of the device rotates, the less time it will take to loosen / tighten the nuts. If for simple devices this parameter does not exceed half a thousand revolutions per minute, then for more advanced it is three times more.
• A variety of attachments that are used in the work, which also serve as a characteristic of the tool. As a rule, no more than a dozen are used for domestic use, in sizes M12-M24. When working with larger dimensions, it is recommended to use a more powerful pneumatic tool.
• Reverse is the rotation of the spindle in the opposite direction to twisting. Not every model is equipped with it. Always be careful when operating such models.

• The material of the tool body also cannot be discounted. The metal body is stronger and more durable, has a higher thermal conductivity while removing heat from the motor. Also, the case is often plastic. Plastic is slightly less durable than metal, but weighs much less, which makes it easier to operate with a wrench.
• When tightening or loosening the nuts in places where access is difficult, use angle wrenches. Such devices have a specific look and are used in relatively specific areas, mainly in manufacturing. They also found wide application in the conditions of a car repair shop.

It should not be forgotten that it is best to choose a nutrunner, guided by the efficiency of the device performing its functions and the degree of its reliability. Various rating polls are carried out, the results of some of them with short comments are presented below. The following models of Chinese, Russian and German production became the leaders in the ratings of cordless impact wrenches.

Reversible model with a half-inch square shaft that is excellent for assembling furniture, assembling car wheels, assembling other metal structures. The clamping force is controlled by the speed control electronics. The power source is an 18 V battery.

Specifications:

• up to 3000 rpm;
• torque - 360 Nm;
• chuck: 1/2 inch square;
• 203 mm long;
• weight - 2300 g.

Advantages:

• metal body;
• the start button is fixed;
• LED backlight indicator;
• excellent ergonomics;
• pulse mode.

Designed for connecting fasteners. Equipped with LED, brush motor with braking device and battery charge indication.

Advantages:

• speed regulation;
• forward and reverse rotation;
• temperature and power fuses;
• the ability to switch to a pulse operating mode;
• ease of use, light weight and size.

It has improved technical characteristics and a wide range of applications. Functionality: nuts, screws, anchors.There is an adjustment of the direction of rotation, switching in 3-speed mode. Possibility of starting a pulse mode. The presence of a battery full discharge fuse and an electric motor braking device.

Advantages:

• four LEDs, smooth rotation switch;
• ease of dismantling rusty bolts;
• the presence of 2 Li-ion batteries, a charger, various mounting attachments, a carrying case;
• light weight, small size and durability of operation.

The disadvantage is the high cost.

Advantages:

• metal case, backlight LEDs, fixing the start button;
• Li-ion battery shuts down when overloaded;
• build quality, handle ergonomics;
• the speed is regulated by the force of pressure on the start button;
• the handle does not slip.

The disadvantage is the low quality of the adapters.

Advantages:

• brush motor;
• die-cast aluminum body;
• protective systems for each function;
• reverse function key;
• fixing the start button during operation, speed adjustment;
• low vibration in pulse mode;
• Li-ion battery with charge indication;
• Possibility of operations with fasteners up to M22.

Disadvantages:

• lack of a spare battery;
• prolonged use will tire the hand muscles.

It differs from similar torque, which reaches 180 Nm, when the approximate standard in this class is only 100 Nm. The reason for this was that in those places where this type of wrench is used, there is no fastener where such a moment would be useful. The wrench is equipped with a built-in frequency control for forward and reverse rotation. The power source is a Li-ion battery.

Specifications:

• there are no additional speed modes;
• 1900 rpm;
• the torque is 180 Nm;
• half-inch square-type chuck.

Advantages:

• replaceable battery;
• shock mechanism of the motor;
• convenient case.

The disadvantage is the high price.

The best brushless cordless impact wrench.

Specifications:

• with reverse;
• additional high-speed mode;
• 2700 rpm;
• torque 165 Nm;
• square half-inch cartridge;
• dimensions - 152 mm;
• weight - one and a half kilograms.

Advantages:

• rotation adjustment is performed by the degree of pressing the start button;
• the developers provide for a two-speed operation scheme;
• the rechargeable battery has a capacity of one and a half to four Ah;
• a portable bag and another rechargeable battery.

It can be called the best inexpensive battery impact wrench. It can be perfectly applied if minor modifications, cabinet repair or something similar are planned. Even with a torque of only 90 Nm, the impact mechanism can handle the rusted fasteners quite well. Its shaft can develop 2000 rpm, with 3000 strokes. The power source is a 12 V Li-ion battery with a capacity of 1.5 Ah, which is enough to operate without interruptions for 240 minutes. The wrench battery has reliable protection from almost all types of impact.

Specifications:

• type - battery reversible impact wrench;
• 2000 rpm;
• torque - 90 Nm;
• weight - 1 kg.

Advantages:

• fast battery charging;
• ergonomics of the case;
• the tool is equipped with an electronic braking device for the motor shaft;
• the transfer of torque to the shaft occurs almost without loss to the metal body;
• LED illumination;
• low cost.

The disadvantage is dissatisfied power when carrying out particularly difficult dismantling.

Specifications:

• type - impact wrench, reversible, battery.
• 1600 rpm;
• 2200 beats / min .;
• torque - 350 Nm when tightening, more than 600 Nm when loosening;
• weight - 3.5 kg including battery.

Advantages:

• fast battery charging;
• battery 54 A / h;
• good ergonomics of the case;
• the presence of an electronic brake for the electric motor.

The wrench has a brushless electric motor and is intended for light to medium installations. It is necessary to note the rational use of the battery by the engine, so that the battery can be charged relatively rarely.

Advantages:

• compactness, light weight, good ergonomics;
• good backlight level;
• electronic speed control.

Every power tool manufacturer tries to make every possible effort to master new technologies that would help improve the quality of the product. This leads to the fact that there is an increase in baseline performance and optional add-ons. But it also leads to the fact that the buyer is lost in the diversity of the choice of models and their capabilities. For this reason, when choosing, it is necessary to constantly be guided by the versatility, functionality of the impact wrench and its compliance with the tasks that need to be solved.

For the DeWALT cordless nutrunner, see the following video.