The Voice of
Torque Control

You are here: News & Events  >  Blog

Blog

19Mar

Introduction to Torque Part 1

What is Torque?

Torque is any force or system of forces that tends to cause rotation about an axis.

 

Measurement of Torque

Imagine someone tightening a bolt using a socket attached to a meter (m) long bar. If they apply 10 kg of force (kgf) perpendicular to the bar they will produce a torque of 10 kgf·m at the axis (the centre of the bolt).

However, under the S.I. system of measurement, force is expressed in Newtons (N) rather than kgf. The conversion between kgf and N is x 9.807 so the person is applying 98.07 N·m of torque.

 

 

 

 

 

 

 

 

 

 

 

The Importance of Torque Control

Although many methods exist to join two or more parts together, the ease of assembly and disassembly provided by threaded fasteners make them the ideal choice for many applications.

The object of a threaded fastener is to clamp parts together with a tension greater than the external forces tending to separate them. The bolt then remains under constant stress and is immune from fatigue. However, if the initial tension is too low, varying loads act on the bolt and it will quickly fail. If the initial tension is too high, the tightening process may cause bolt failure. Reliability therefore depends upon correct initial tension. The most practical way of ensuring this is by specifying and controlling the tightening torque.

Bolt Tension

When an assembly is clamped by tightening a nut and bolt, the induced tension causes the bolt to stretch. An equal force acts to compress the parts which are thus clamped.

The proof load of a bolt, normally established by test, is the load which just starts to induce permanent set – also known as the yield point. Typically, bolts are tightened to between 75% and 90% of yield.

Product Selector

Find a Distributor

Norbar Videos

What Our Customers Say

Download Our Apps

FAQ

Use Our Calculators

Norbar has devised easy-to-use online calculators that support the correct application of torque in three key areas:

  1. Unit conversion to assist international measurement definitions.
  2. Torque extension for setting correct values
  3. Torque tension to identify precise levels of torque to be applied for individual applications.

Goods Return Form

NORBAR TORQUE TOOLS LTD. Wildmere Road, Banbury, Oxfordshire, OX16 3JU, United Kingdom
Registered Office as above - Registered in England No. 380480 - VAT No. GB 119 1060 05