Torque is the combination of a tangential force acting at a distance from the axis of rotation.
When you turn the steering wheel of a car, or push and pull the handlebar of a bicycle, you are generating a torque.
Torque is measured in many different contexts from controlling the tightness of a soft drink bottle cap, to measuring the output of a ship’s engine. Most applications of torque however are related to the control of threaded fasteners.
Threaded fasteners have been in existence for thousands of years. The thread turns rotation into linear movement. The primary purpose of this linear movement is to clamp together two or more pieces of material. This is called a joint. The fastener must create a clamp force so strong that the pieces of material do not move apart during use of the assembled product. The clamping force should have been calculated by the designer who will have studied the forces acting on the joint.
One of the more frequently asked questions from our customers is “Why do we torque bolts and how do I select the correct torque wrench for application?”
Generally, most torque wrenches are used for tightening nuts and bolts accurately. Nuts and bolts need varying degrees of accuracy depending on the materials being fastened together, and therefore, there are different wrenches for different applications.
The two main reasons for the importance of torquing and why we use torque wrenches is firstly to achieve the correct level of tightness and then to ensure consistency across all of the bolts in the assembly. Used properly, a torque wrench will ensure that all bolts have the same level of torque applied. The effect of badly tightened bolts can be seen in lost time and money. The bolt needs to be stretched to create a clamping force on the assembly. If the torque value is too low, the assembly will not be secure. If the torque is too high, the bolt may break. The torque wrench allows the operator to tighten the bolt as the designer intended.
The other reason to use a torque wrench is to be consistent on every bolt in the assembly. Used properly the torque wrench will ensure that all bolts have the same torque applied.
The effect of badly tightened bolts can be seen in lost time, money and lives. A machine stops working and takes weeks to repair. A bridge collapses. A wheel comes free from a truck and hits a car travelling in the other direction. Good quality torque wrenches do save time, money and lives, and just goes to show the importance of torquing.
The most common wrench is called a click wrench. It will indicate by a mechanical mechanism when a pre-set torque has been reached. The pre-set value can be set by the user, or by a Quality Control Department. The second most common torque wrench is used to check an already tightened bolt.
It can have a mechanical or electronic sensing mechanism and can display by means of an electronic or analogue display.
There are many different styles and qualities of torque wrench available. With the correct selection, operation and maintenance, a torque wrench can save you time and money. To make the correct decisions you may need to seek the advice of specialist torque tool provider like Norbar Torque Tools.