How To Use a Torque Wrench

How To Use a Torque Wrench

How to use a torque wrench
http://www.youtube.com/watch?v=zgwwOJ0B964
http://www.norbar.com/

This video from Norbar Torque Tools, the world’s torque specialists, takes you through the best practice use of a Norbar Torque Wrench.

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 other tools referred to as “torque wrenches”. These are powered by pressurised oil or air and are known as hydraulic or pneumatic torque wrenches. The use of these devices is more complex and will be covered in a later article.

Most torque wrenches are used for tightening nuts and bolts accurately although there are also some other uses. These other uses will be discussed in another article. There are two main reasons why we use a torque wrench.

One reason is to achieve the correct level of tightness. 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.

The largest part of the uncertainty comes from the operator. Problems will arise if the torque value cannot be set correctly. Unfortunately many wrenches have a scale that is difficult to read, or becomes worn away with use. It can also be difficult to position the cursor accurately. Some wrenches have a vernier scale to help. These will only work with one set of units. Be sure whether the vernier is designed for the N.m, kgf.m or lbf.ft scale.

The operator will also affect the torque by using the wrench too fast. The “click” wrench is designed to give a physical signal when the desired torque is reached. If the wrench is operated too quickly, the torque will go too high before the operator can stop.

With dial or electronic indicating wrenches, the operator must be able to see the dial or display. This can be difficult in applications where there is poor light or limited access. Finally the operator must apply a smooth and slow force at 90 degrees to the wrench. Side loads can alter the torque applied and may cause the wrench to slip off the bolt.

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.

Further information on the use of Norbar’s products can be obtained from our website, from the literature supplied with them and by contacting Norbar or our distributors.
How To Use a Torque Wrench



How To Use a Torque Wrench