Torque is the turning force of the cordless impact driver and is needed to complete tasks such as inserting or removing screws and drilling. More demanding tasks (e.g. working with tougher materials or larger screws) will require higher levels of torque. Every cordless drill driver can produce torque, but some can produce more than others.
Torque is measured in Newton Metres. A cordless impact driver’s torque rating will be presented as a number followed by ‘Nm’. The higher the number, the more torque that tool can deliver.
Compared to a cordless screwdriver or drill driver, an impact driver can deliver a much higher level of torque due to its impact function. Most cordless impact drivers can deliver a maximum torque level of 150 Nm! To put this in perspective, cordless drill drivers produce around 40 Nm of torque, and cordless screwdrivers produce around 10.
Torque and speed
A cordless impact driver is operated using the speed control trigger. Squeezing the trigger starts the chuck turning. The further you pull the trigger in, the more torque will be delivered, and the faster the chuck will turn. The more you release the trigger, the less torque and speed will be delivered. Releasing the trigger completely stops the impact driver.
In the case of cordless drill drivers and screwdrivers, torque and speed have an inverse relationship (when one increases the other decreases). For these tools, squeezing the trigger increases speed but decreases torque, and releasing the trigger decreases speed but increases torque. This is because the motor’s power is a combination of torque and speed, so one must always decrease in order for the other to increase
Cordless impact drivers on the other hand, are much more powerful. Due to the additional torque supplied by their hammer and anvil mechanism, they can produce both high torque and high speed, simultaneously. This allows them to drive screws and drill holes much faster than a cordless drill driver or screwdriver.