It is important to know what a torque wrench is before we discuss the types of torque wrenches available in the industry. A torque wrench is used to either tighten or loosen a fastener (bolt or nut) by applying the right amount of torque on it. As Newton’s 3rd law states, every action requires an equal and opposite reaction, applying the high value of torque, the wrenches would require a reaction arm to lock itself at an adjacent point.
The fastener is ideally lubricated before starting the process. This article will talk about the different types of torque wrench with their advantages and disadvantages. While there are many different types of torque wrenches in the industry, we shall focus on the automated high newton meter capacity torque tools.
1. Hydraulic Torque Wrench
The most popularly used torque wrench in the industry, hydraulic torque wrenches are powered by hydraulics (oil) using a pneumatic or electrically driven hydraulic pump. It is commonly used as it offers the highest power to weight ratio, i.e. it offers the widest range of toque inversely proportionate to the weight of the tool. It is also one of the most accurate torque output with +/- 3% accuracy. Thus, making hydraulic torque wrenches portable and flexible of use. Hydraulic Torque Wrenches are available in two types; square drive (external socket required) and direct fit (hex) drive variants.
Since Hydraulic Torque Wrenches can achieve high torque values, placement of the reaction arm is crucial to protect the housing of the tool from an unwarranted external force. Ideally, the reaction should be taken in a plane parallel to the axis of the bolt. Square drive hydraulic torque wrenches have reaction arms mounted on the cylinder portion of the tool. Other torque wrenches with the reaction arm mounted on the cylinder at the back have the disadvantage of the reaction arm not being parallel to the axis of the bolt when convenient reaction points are not available. Having the reaction arm mounted in the front of the tool, coaxial to the square drive provides a 360-degree plane. On rotation of the reaction arm itwill always be parallel to the axis of the bolt to provide a stress-free cylinder as the reaction arm is not mounted on the cylinder.
Before purchasing a torque tool, prospective buyers should always consider the design of the square drive Hydraulic Torque wrench.
2. Pneumatic Torque Wrench
Powered by compressed air, pneumatic torque wrenches are mostly popular in the automobile industry. It operates fast and provides an accuracy of +/- 5%. However, pneumatic torque wrenches need constant high air pressure which disallows the tool to be operated at great heights. Modern pneumatic torque wrenches come with dual speed mode to improve productivity. Fast tightening is possible with the rundown mode and torque mode offers precision tightening.
3. Electric Torque Wrench
Unlike hydraulic and pneumatic torque wrenches, electric torque wrenches do not require a pump or compressed air to power them as it runs on electricity and can be directly connected to a power source like an electric socket. Offering an accuracy of +/- 5%, these tools cannot be used in all industries due to the possibility of spark generation which risks its usage in explosive industries like oil and gas, petrochemical and mining. Being heavy and having an unbalanced weight adds more to its disadvantages.
4. Battery Torque Wrench
The most developed and modern torque wrench in industrial bolting, a battery torque wrench offers the highest portability as they operate on battery and do not require pumps or compressed air. These torque tools operate on battery placed at the bottom of the tool which offers a similar accuracy of +/-5% like electric and pneumatic torque wrenches. The only disadvantage of this torque tool is that it offers lower maximum torque capacity in comparison to hydraulic and pneumatic torque tools.
In conclusion, based on industry requirements, different torque wrenches are designed to provide different options and solutions. It provides customers the flexibility to choose which wrench suits their requirements best. Visit us next time to know more about industrial bolting.