In essence, all torque tools do the same thing. They apply radial force to a fastener in order to tighten it or loosen it in its socket. In addition, to be known specifically as torque tools, they must have some mechanism to limit the amount of torque their operator applies. This torque limiting mechanism is what separates torque tools from all other tools.
It’s important to deliver appropriate amounts of torque to fasteners. Delivering either too much or too little torque can cause the fastener to fail. The more critical the assembly, the more important it is to deliver the correct amount of torque. Likewise, high volume assemblies require reliable torque control to increase repeatability and decrease lost or defective product.
Torque tools can be hand, electric, or air powered. Each class of tools relies on different torque limitation methods, and different methods are most effective for different applications. To find the torque tool that’s best for your application, read through our guide to the various torque wrench delivery mechanisms:
Hand Tools
Limiting Mechanism
The click wrench deflects by 3° and emits an audible click when torque is reached. The operator should hear and feel this click and and stop applying force. Because click wrenches do not physically prevent operators from applying more torque than is needed, they are best suited for less critical applications.
Break-over wrenches are similar to click wrenches in that they limit torque by deflecting. A joint between their head and shaft “breaks” when torque is reached, deflecting 20-90°. This prevents operators from over-torquing without resetting their wrench. This added level of torque control makes break-over wrenches more suited for critical applications than click wrenches.
Cam-over wrenches physically prevent their operators from over-torquing fasteners by slipping, or disengaging their clutch, when torque is reached. Even if operators try to use the tool on the same fastener after it has slipped, it will simply slip again, refusing to deliver more torque than specified. This total control over torque delivery renders cam-over wrenches ideal for the most critical torque applications. Hand torque screwdrivers also use cam-over torque technology to limit torque delivery.
Power Tools
Clutch drive electric screwdrivers limit torque in a similar way to cam-over wrenches, by disengaging their clutch when the proper amount of force has been applied. This provides a high level of torque control, making them useful for critical applications. However, unlike hand tools or DC control tools, these screwdrivers apply force at a constant rate. As such, they can damage sensitive parts, such as plastics, and should be avoided for delicate applications.
Rather than limiting torque directly like clutch drive tools, DC control electric screwdrivers limit torque indirectly by controlling the electric current which flows to the screwdriver’s motor. DC control tools can increase productivity by allowing you to use one tool instead of 2-8 tools. They also allow for error-proofing and real-time monitoring, allowing you to collect and save fastening data for traceability purposes.
Continuous drive pneumatic wrenches rely on compressed air to deliver torque and a clutch mechanism to limit torque. While less precise than electric tools, continuous drive pneumatic wrenches can accurately deliver much higher amounts of torque.
Pulse wrenches use compressed air to deliver torque in a series of extremely rapid bursts. While slightly less accurate than continuous drive pneumatic wrenches, pulse wrenches generate significantly less reaction force. This protects their operators from developing musculoskeletal injuries due to repeated absorption of reaction force.
Now that you have a good idea of the different torque wrench delivery mechanisms, the next step towards finding the right wrench is identifying the amount of torque you need to deliver, how fast you need to deliver it, and whether your application has any special considerations, such as a non-standard head or clean room requirements. At this point, you should have everything you need to know in order to find the right tools for your operation.
At Mountz Inc., we work to make sure you have the right tool for every job. To see our full range of torque tools, browse our catalog. Contact us anytime to ask a question. To inquire about price, request a quote. If you’d like to see our equipment in person, schedule an appointment.