BOLTCALC Torque Analysis Screenshots - Bolt Science Torque Analysis Scre… · Microsoft Word -...

Performing a Torque Analysis using the BOLTCALC® Program

Using the BOLTCALC Program to perform a torque analysis of a threaded fastener

BOLTCALC IS A REGISTERED TRADEMARK OF BOLT SCIENCE LIMITED

TORQUE ANALYSIS USING THE BOLTCALC PROGRAM

This is the problem we are going to completing an analysis on.

Start the BOLTCALC program

Use the menu option, Analysis Type – Torque Analysis


A window with tabs will appear. The first tab is for remarks and any free text can be entered into the boxes. This text data will be saved with the rest of the program data if the save option is used.

The Bolt Details page is selected by clicking on the tab.

On the Bolt Details page, the Thread Database can be selected by clicking on the button indicated.


The Thread Database window will appear. Scroll down the box on the right hand side until you reach the required thread size. Click on this to enter all the details relating to that thread into the boxes on the screen.

By clicking OK, this information will be entered onto the Bolt Details page.

Next, the bolt is property class 10.9. To select this property class, the yield strength can be directly entered into the program, or alternatively, the button: ‘Consult the Fastener Material Database’ can be clicked.

A separate window appears allowing the selection of 10.9 to be made by clicking on it. Then click OK to enter the strength details into the program.


Next click on the Tightening Details Tab to select this page.

The default coefficient of friction used by the program is 0.12. This can be changed by directly entering the value into the relevant box, or alternatively, there is a Thread Friction Database that can be accessed by clicking the relevant button.

Once clicked, another window opens allowing you to select the appropriate finish or lubricant. In this case since the default value is being used, the Cancel button is pressed so that any data selected from this form is not entered into the program.


If the Nut Face Friction Database is required to be viewed, this can be accessed by clicking on the button shown. In this example since the default value is being used, the database is not needed.

There are three ways in which the tightening condition can be defined.

The first approach is the yield factor method. This is the default approach and can accessed by double clicking on the button.

A window appears that offers further information on the approach. The default 0.9 value will be used. Click OK to close the window.


All the data is now entered into the program. To complete the calculations, press the Calculate button.

The results screen then appears. This can be printed out if desired. (By the menu option – File – Print.)

Scrolling down the screen, the torque and preload values are displayed. In this example the torque value is 583 Nm and the preload 185836 N.

Let’s say, we require the preload at a rounded figure such as 600 Nm.


To access the Data Entry Form again, the menu system (Analysis Type – Torque Analysis) can be used. Alternatively, the relevant speed button can be clicked as shown on this screen.

To enter the 600 Nm torque value, click on the Tightening Details Tab and then double click on the Tightening Torque button, as shown here.

A window appears allowing you to enter a torque value, entering 600 into the box and then clicking the OK button.


Once the Data Entry Form appears, click the Calculate button to display the results.

The results now appear for the 600 Nm torque value entered. As can be seen, the percentage of yield utilised is now 92.6% and the preload is 191202 N.

Let’s say, you now want to know how much torque is needed to achieve a preload of 200000 N.

Go to the Data Entry Form again by clicking the Torque Analysis speed button.


Go to the Tightening Details Tab and double click on the Assembly Preload button shown.

The 200000 N value can now be entered and the OK button clicked.

Click the Calculate button again to compute the torque needed to achieve the 200000 N preload.


The results are now displayed. As can be seen, a torque of 627 Nm would be required to achieve the 200000 N preload and 96.86% of the minimum yield value of the bolt would be used.

If required, some graphics can be displayed by selecting the menu option: View – Torque Distribution Graph

Once selected a piechart will appear showing how the torque is distributed between the thread extension, the thread friction and the nut face friction.


If required, a one page summary can be created. This is selected using the menu option: File – Tightening Results Summary

Once selected the summary of the results is displayed. This can be printed by clicking on the button.

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