The Ultimate Guide to Electric Torque Wrenches

(Last Updated On: August 24, 2023)

Electric torque wrench, also known as adjustable torque electric wrench, its main feature is that the torque can be set and adjusted. Electric torque wrenches are generally divided into plug-in and battery-type. The working principle of the two is the same, only the power supply method is different.

In this article, we discuss the following issues around electric torque wrenches.

1. what are electric torque wrenches?
2. How does an electric torque wrench work?
3. Application of electric torque wrench.
4. How to use an electric torque wrench?
5. Precautions for the use of electric torque wrench.

I hope this article can give you a direct understanding of electric torque wrenches. now let’s start!

What Are Electric Torque Wrenchs?

An electric torque wrench is a type of wrench used to precisely apply a specific amount of torque to fasteners such as nuts and bolts. It sets and adjusts torque and drives the motor with electric energy to generate torque.

An electric torque wrench usually consists of a handle, a motor, a gearbox, a module for measuring and controlling the applied torque, and a digital display.

Electric torque wrenches are often seen in industries such as automobile maintenance, construction, manufacturing, aerospace, and steel structure installation. Because of its ability to precisely set the desired torque level, this helps maintain the structural integrity of the fastener and prevents the bolt from being over- or under-tightened. Therefore, it is very popular in these industries.

How Does an Electric Torque Wrench Work?

The working principle of the electric torque wrench is a complex system, and each part will have a corresponding role. The following is a brief introduction of its working principle:

1. Motor: There is an electric motor inside the electric torque wrench, which can convert electrical energy into mechanical motion. When starting, the motor generates rotational force, which drives its square drive or low profile drive through the wrench’s gearbox to tighten or remove bolts.
2. Gearbox: The gearbox contains a set of planetary gears to increase or decrease the speed and torque generated by the motor.
3. Torque measurement: The electric torque wrench detects the resistance encountered when tightening the fastener through the strain gauge, load cell, or other sensors integrated into the tool converts it into torque, and displays it on the screen.
4. Control mechanism: The control unit of the wrench is responsible for adjusting the power output of the motor to achieve the required torque.
5. Feedback system: The electric torque wrench provides real-time feedback to the user through visual or auditory indicators. When the applied torque reaches the set torque value, a prompt will be displayed on the display and a prompt will sound.

Therefore, combining the functions of each part above, the electric torque wrench works like this.

When using an electric torque wrench, the operator uses the control mechanism to set the desired torque value. The control mechanism adjusts the output power of the motor to output enough torque to the wrench’s gearbox (consisting of a set of planetary gears). The gearbox outputs the amplified or reduced torque to the square drive or low profile drive to tighten or remove bolts. When the specified torque level is reached, the motor will stop rotating, a prompt will be displayed on the display and a beep will sound.

Application of Electric Torque Wrench

Electric wrenches are mainly used in automobile maintenance, construction, manufacturing, aerospace, and steel structure installation industries, and are specially used for fastening high-strength bolts. High-strength bolts are used to connect nodes, usually in the form of bolt sets.

In these industries, electric torque wrenches are suitable for high-strength bolts of the following types.

High-strength bolts can be divided into two types: torsional shear type and large hexagonal type.

Torsional shear-type high-strength bolts include M16, M20, M22, M24, and now there are non-national standard M27, M30.

Large hexagonal high-strength bolts include M16, M20, M22, M24, M27, M30, etc.

The tightening of high-strength bolts must be tightened first and then finally, and each step requires strict torque. The initial tightening and final tightening of large hexagonal high-strength bolts must use a constant torque wrench.

How To Use an Electric Torque Wrench?

The constant torque electric wrench can be used for both initial and final tightening. When using it, adjust its torque first, and then use it to fasten the bolts.

1. Before starting the main engine, install the reaction arm of the electric wrench and find the support point of the reaction arm. Adjust the square drive head of the wrench to match the square socket over the nut.
2. Manually adjust the control button on the LCD screen of the wrench, adjust the torque of the controller to the torque value required for tightening, and determine the forward and reverse directions of the electric wrench.
3. Press the start button and the wrench starts to work. When the reaction arm of the electric wrench is firmly supported (the fulcrum can be an adjacent bolt or other position that can be used as a fulcrum), the bolt starts to be tightened. When the torque of the bolt reaches the predetermined value, the wrench will automatically stop to complete the tightening work.
4. If the reaction arm and the support point are stuck too tightly and cannot be separated, adjust the forward and reverse switches to the reverse direction, and then move the trigger wrench to remove it.

Precautions For the Use of Electric Torque Wrench

In order to ensure the integrity of the bolt fastening and prolong the service life of the electric torque wrench. Pay attention to the following issues when using an electric torque wrench.

1. The fastening of high-strength bolts should be carried out at least twice. The first time is the initial tightening. The minimum torque value of the initial tightening is not less than 40% of the torque value required for tightening. The second time is the final tightening. In order to make all the bolts in the bolt group evenly stressed, the initial tightening and final tightening should be performed in strict accordance with the tightening sequence. Operate symmetrically according to the “double-cross” shape.
2. Operate in strict accordance with the operating procedures of the electric torque wrench. The bolts that are initially screwed should be marked for confirmation to prevent bolts from being skipped. When installing the bolts, ensure that the friction surface is in a dry state, and the final tightening torque must be carried out according to the requirements of the set value.
3. Due to the influence of external force, temperature change, vibration, and other factors on the torque or pre-tightening force of the bolt, the final torque value produced each time is different, and the torque deviation is normal within ±5%.
4. For the electric wrench whose torque has been set, it can be rotated 30° from the pre-tightening of the bolt to the tightening. For the bolts that have reached the set torque, there is no need to use the wrench again, otherwise, the bolt torque will be increased, and the load of the bolt and the electric wrench will also increase, which will damage the bolt and the wrench.
5. Clean and replace grease regularly. Generally, after working 5000 times, it should be cleaned and refueled to prolong the service life.

In The End

Electric torque wrenches are one of the most commonly used bolting tools and can be used in various industries. TorcStark has recently introduced new pneumatic torque wrenches and electric torque wrenches, and our wrenches have been tested in the market for a long time and have been recognized and praised by many customers (click here to view the latest TorcStark pneumatic torque wrench and rechargeable electric torque wrench). If you need a torque wrench and want to find a reliable supplier, please contact us.