ABSTRACT
We have now reviewed the assembly process and have seen why the control of that
all-important clamping force on the joint is so difficult. During this review we assumed
that we were using the torque applied to the nut to control the tension or preload built-up
within the bolt. Now we’re going to take a much closer look at torque control itself. We’ll
learn how to estimate the initial preload we’ll achieve by applying a given torque to a fastener;
we’ll take a brief look at torque tools; and we’ll look at ‘‘restarting’’ or ‘‘breakaway’’ torque
as a means of evaluating the residual preload in a bolt.
