About Torque

What is torque?

• Torque is the measure of a force’s tendency to produce rotation or torsion.
• The measure of Torque is now used for screw fastening using a tools like hexagon wrenches.
  • Torque is defined as “Force” × “Lever-arm distance”.

For instance, when holding and applying force to a hexagon wrench inserted in a hexagon socket head bolt at 0.2m away from the center of the bolt with force of 10N, the tightening force is; from the Formula : FXL=T (F: Force N, L: Lever-arm distance m, T: Torque N・m) 10N × 0.2m = 2.0 N・m It is also deduced from the Formula that F (force applied) necessary to obtain the tightening torque of 2.0 N・m with L:0.4m is 5N.

• ISO and JIS stipulate a guaranteed torque value for each size of hexagon wrenches within which they will not be broken, twisted, distorted in a hexagon shape or bent to the extent that they will become unusable. They also demonstrate the test method with a torque wrench.
• ISO and JIS specify that hexagonal wrenches shall not be broken or cause any irregularities such as twisting, deformation in the hexagon shape, or bending when used within proof torque values (ISO 2934,JIS B 41648).

-JIS specification shows proof torque values for each size as well as the test method using a torque wrench.

Maximum torque that human hands can produce

(test value of hexagon wrenches)

*The figures with (*) mark = The maximum torque human hands can produce exceeds the maximum value of hexagon wrench.