What Is A Torque Bolt Chart?

Torque helps create tension while bolts are used to fasten two components together to enable them to resist tensile and shearing forces. A bolt torque chart shows recommended torque values and related bolt clamping pressures for various sizes and specifications of fasteners. Using too much torque, or not enough, can lead to trouble. 

To create tension in a bolt, torque is necessary. Turning a nut onto a bolt with torque causes the bolt to flex, creating a powerful spring that fastens the two materials together. Torque is used in almost every step of fastening, including tightening.

A torque bolt chart helps you to determine the correct amount of torque you can administer to a bolt you're replacing or tightening. But it can provide additional information as well. Let’s take a look.

The Essence of Torque

Bolts and screws can't function without proper torque. In transportation, a failed bolt or screw can cause a safe journey to be interrupted by an unplanned hard stop.

If you don’t use enough torque to tighten a bolt, you run the risk of it bending, or just simply not providing the clamping force that’s needed. But if you over-torque a bolt, it could end up breaking.

Likewise, bolts and screws could fail in several ways without proper torque. They can unfasten under vibration and release if they don't get enough torque. In that case, they'll find it hard to hold their load and become unfamiliar waste objects, causing notable damage as they clatter around.

Bolts must be tightened using the proper torque. A well-torqued bolt will give the maximum amount of clamping force under load.  

Determining The Required Torque And Tension

Many factors influence the torque-tension relationship, such as human error, surface roughness, and lubrication. You have to take all of this into account when tightening to a specific torque. Your results may vary.  The only method to discover the proper torque is to experiment with actual joint and assembly settings.

Bolt torque offers only an indirect estimation of material stress. It is predicted that about 10 percent of the torque tightening results in appropriate bolt tensioning. The rest is lost because of different friction forms during the tightening process.

Also, a proper bolt torque value could be incompatible from fastener-to fastener due to many factors. These include coatings, installation methods, fit tolerances, surface finishes, variations in material, etc. As such, it's not practical to offer one precise bolt torque chart for all situations.

A Solution to Your Fastener Needs

Using a torque bolt chart is a great way to find the ideal torque for all your fasteners. You should always ensure that you're using the proper torque when tightening nuts and fasteners. Torque tightening is the precise application of torque to a nut to enable a bolt to hold its load firmly without breaking.

But you can also determine how your bolts may hold up by making sure your supplier is manufacturing them with quality in mind.

You should never sacrifice quality when it comes to fasteners, and Big Bolt thrives on making quality fasteners—quickly. Whether it’s an emergency or an extremely unique design, Big Bolt will make it for you if we don’t already have it in our inventory. We can also turn them around in a day (if needed).

For more information, contact Big Bolt today.