Glossary

The terms clamp load and clamping force are closely related and often used interchangeably, but there’s a subtle distinction in how they’re defined and measured within fastener mechanics.

Clamp load refers to the tensile force generated in a fastener (such as a bolt or screw) when it is tightened. It is the internal tension that develops as the bolt stretches elastically, much like a spring being pulled. This stored tension is what creates the compressive force between the joined parts. In other words, clamp load is the result of tightening torque applied to the fastener.

Clamping force, on the other hand, refers to the compressive force acting on the joint members themselves—the pressure that holds the components together. It’s the external manifestation of the bolt’s internal clamp load. In a properly designed joint, the clamp load and clamping force are equal in magnitude but opposite in direction: the bolt is in tension, while the joint is under compression.

To put it simply:

 - Clamp load = the tension inside the bolt created during tightening.

 - Clamping force = the compression applied to the joint as a result of that tension.

In an ideal system, these forces balance each other exactly. However, factors like friction, material deformation, surface roughness, and joint flexibility can cause minor differences between the two in real-world applications.

In summary, clamp load is the internal tensile force within the fastener, while clamping force is the external compressive force applied to the jointed parts—two sides of the same mechanical interaction that ensures the joint remains tight and secure.