How to choose a pneumatic wrench

Start the selection with the torque required for the joint being made. The working value should fall within the range handled by the specific wrench, so before choosing you need to know the requirements of the joints on which the tool will be used most often.

If several models cover the required torque value, the next criteria become the working conditions: available space, how the tool is positioned, drive size, weight, working speed and the requirements placed on the pneumatic installation. A wrench should be chosen to suit the whole process, and not only the maximum Nm value given in the specification.

Match the torque range to the joints you make

The demand for torque can vary greatly depending on the size and type of the joint. Regular work with bolts requiring a few hundred Nm calls for a different tool than heavy industrial joints measured in several or even more than ten thousand Nm.

When working with many types of joints, the span of the wrench's useful range is important. If the tool is to be used for a single repetitive task, it becomes more important to match the range well to the specific working value.

The maximum torque alone should therefore not decide the choice. A more powerful tool may be larger, heavier and less convenient in applications that do not make use of its capabilities.

Straight or angle wrench?

The design of the wrenchmainly affects how it can be positioned in relation to the joint.

Straight models work well where there is enough room around the bolt to position the tool body along the working axis. Where access is limited, an angle wrench may be the better solution, as its design allows the drive to be positioned differently in relation to the joint.

Before choosing, it is worth checking not only the space around the bolt itself, but also the room needed for the tool body and for safely supporting the reaction arm. In installations, steel structures, machines and enclosed assemblies, access to the joint often decides which version of the wrench to choose.

Check the drive size and the sockets you use

Pneumatic wrench intended for different torque levels may be equipped with drives of different sizes. Before buying, therefore, check whether the selected model will work with the sockets and accessories used on the joints you make.

This is particularly important when the wrench is to be added to an already existing set of tools. Matching the torque is then only one element of the compatibility of the entire working setup.

The reaction arm is part of the tightening process

At high torques, the reaction generated during tightening must be safely transferred to a suitable support point. This is the job of the reaction arm working with the wrench.

Already at the tool selection stage, it is therefore worth checking where the arm will be able to rest during work. In some applications, being able to support the arm correctly can be just as important as the torque range of the wrench itself.

Especially with unusual structures, limited space or joints located close to other components, you need to consider the whole setup: the wrench, the socket, the reaction arm and the operator's access.

Check the requirements for the pneumatic installation

A pneumatic wrench requires a suitable source of compressed air. Before buying, check the working pressure required for the specific model, the air consumption and the manufacturer's recommendations for preparing the installation.

It is not only the nominal pressure of the compressor that matters. The installation must provide the right parameters during the actual operation of the tool as well. Insufficient capacity of the installation, unsuitable hoses or large pressure drops can affect the operation of the entire system and the torque achieved.

If the wrenchis to be used at an existing workstation, it is worth comparing the requirements of a given model with the parameters of the available pneumatic installation before choosing it.

How is torque set on a pneumatic wrench?

An air preparation unit is used to adjust the torque on a pneumatic wrench. It is a control module to which the compressed air supply is connected; the module is equipped with a valve that controls the pressure of the air delivered to the wrench's drive. Using a pressure gauge, the user sets the required air pressure. A specific pressure value corresponds to a specific torque value, and this information is contained in the torque table supplied with the wrench.

Pneumatic, cordless or electric wrench?

Pneumatic drive works particularly well at workstations where access to compressed air is a permanent part of the infrastructure. There is then no need to manage charging and replacing batteries, and the tool can be used for regular work on successive joints. They are also very often used in areas with an increased risk of explosion, where tools with an electric drive cannot be used, for example during work in refineries or in mining.

If the work takes place in different locations and it is important to be able to move freely without a pneumatic hose, also check cordless multipliers.

For workstations with permanent access to electricity, electric multipliers are an alternative.

Choose the type of drive primarily to suit the place where the work is carried out, the available infrastructure and how often the tool will be moved between workstations.

Inspection and calibration of torque wrenches

A tool used to make joints with controlled torque should maintain the parameters required in a given process. The frequency of inspection depends, among other things, on the manufacturer's recommendations, the intensity of use and the requirements in force at the plant.

Regular verification makes it possible to confirm that the wrench is still working to the required parameters. For tools used in processes that require documented torque control, keeping appropriate documentation is also particularly important.

At TorqueShop we offer service and calibration of torque tools. The scope of service for a specific wrench can be agreed according to the type of tool and the service required.

FAQ

Which is better - a wrench or a power screwdriver?

It depends on the type of work being done. A power screwdriver is intended mainly for driving and removing screws and for lighter joints, so it is well suited to assembly, workshop and construction work. A wrench is the better choice for bolted joints requiring much higher torque. Industrial pneumatic wrench are used, among other things, on large bolts, steel structures, machines and installations, where controlled tightening to a specified torque is required.

What is the most powerful wrench on the market?

There is no single universal "most powerful wrench", because there are different classes of tools on the market, from hand-held cordless multipliers to specialist industrial systems for very large bolted joints. Professional pneumatic wrenches can reach torques measured in tens of thousands of Nm, and specialist pneumatic systems available on the market reach as much as 300,000 Nm. When choosing a tool, however, the range matching the specific joint and the conditions in which the wrench will be used are more important than the maximum torque available.

Can a wrench be used to drive screws?

Technically, a wrench can turn a threaded element when suitable accessories are used, but industrial pneumatic wrench are not intended for typical driving of screws into wood, sheet metal or plastics. Their applications are primarily bolted joints requiring high, controlled torque. For standard screws, it is better to choose a power screwdriver, which provides suitable control, handling and torque range.