TORQUE Program

Threaded Fastener Torque Tightening Program

The Problem
A survey of car service managers completed in the United States, indicated that 23% of all service problems were traceable to loose fasteners. Such problems are common across many industries. A major cause of fastener loosening is inadequate tightening. A single bolt, inaccurately or incorrectly tightened, can lead to the failure of the complete product.

Torque Controlled Tightening

The most prevalent controlled method of tightening threaded fasteners is by tightening so that a specified torque is achieved. This method is generally known as torque control. The major problem related to this method is that the fastener clamp force (referred to as preload) generated as the result of an applied torque is dependent upon fastener design and the prevailing frictional conditions. Despite these problems, it is still the most popular way of ensuring that an assembled bolt complies with an engineering specification.

The Importance of Tightening Torque

Most Engineers already know the importance of a high preload in maintaining joint integrity. For torque controlled tightening, achieving the right preload is dependent upon the correct tightening torque being specified. Without the proper analytical tools and information, specifying the correct torque can be problematical. Whether you are a Service or a Design Engineer, you frequently need to know what is the correct tightening torque. For many types of threaded fasteners, this information is either not available, or not readily available.

Analysis of Bolted Joints

A great deal of sophistication can nowadays be applied to the analysis of structures. Frequently however, the assumptions made in the analysis regarding the scatter in a bolts preload, is either simplistic or is ignored. That is, it is often assumed that a bolts preload will not vary from a single calculated or test determined value. Frequently, this can be a fatal flaw in the structural analysis. Fluctuation in a bolts preload is mainly caused by variations in the frictional conditions and the method of tightening being used. If this fluctuation is outside the assumed value, product reliability problems can result. Such reliability problems can manifest themselves as fluid leakage past a gasket, fatigue failure of the bolt itself or of the whole joint. Being able to predict what will be the minimum fastener preload can be crucial to the reliability of a product.

The TORQUE Program

TORQUE is a program which is designed to assist the Engineer in the solution of problems related to the torque tightening of threaded fasteners. The program determines both tensile stress due to the elongation of the fastener, and the torsional stress due to the applied torque. It accounts for the frictional effects in the thread and between the nut face and clamped surface. Account can also be made for the effects of a reduced shank diameter (smaller than the thread size) and a prevailing torque. The prevailing torque is the torque required to run a nut down a thread before engagement with the joint surface. This resistance can be provided by a nylon insert or a distorted thread profile. A prevailing torque can significantly affect the amount of preload provided by the fastener for a given tightening torque.

Versatile Analysis Options>

The program analysis options include the determination of :

a) The tightening torque and preload so that a given stress level is achieved in the fastener.

b) The tightening torque having specified the preload required.

c) The preload having specified the tightening torque.

Menu Options

An in-built database is provided containing information appertaining to thread pitch, root, effective and nut bearing diameters for standard fasteners. The default metric coarse thread data used by the program can be changed to metric fine, Unified Coarse or Unified Fine by selecting the appropriate menu option. Similarly, the default metric unit of measure can be changed to various imperial units by selecting an appropriate menu option.

Help

Help is available which can furnish information relating to both the program and to threaded fasteners in general. Help is available for each input value which is required by the program by pressing the F1 function key at any time during entry.

The program has menu options to allow :

a) Printout of the results and the data to both the screen and printer.

b) The program has the facility to store both data and the results to disk.

c) Previously stored data can be retrieved and subsequently used by the program.

User Guide

A user guide is supplied as an Adobe pdf document and is installed with the program. The manual, besides giving guidance on the use of the program, presents valuable background information on the tightening of threaded fasteners.

System Requirements

TORQUE runs under Windows 95, 98, ME or NT, 2000 or XP. TORQUE is provided as a download from our web site.


Torque pdf Datasheet Presented below is further information related to this program.

Example calculations (METRIC) completed by TORQUE

Example calculations (Inch/Lb) completed by TORQUE

Torque Datasheet in Adobe pdf format

The download for our demo program is packaged in a self extracting exe file that includes an uninstall facility if/when you want to cleanly remove the program and associated files from your system. To install the program when you have downloaded the file you need just to run it by double clicking on the file from Explorer or by using the Run option from the Start menu.

TORQUE Demo Program

Pricing and ordering details for the program