Why tightening spec is really about clamping force, not the wrench reading.
Ask most people what a torque spec on a bolt is for, and they'll say it's to make sure the bolt is tight enough. That's close, but it skips the part that actually matters. What holds a joint together — resists separation, keeps mating parts from working loose, and in many cases keeps a fastener from ever seeing meaningful cyclic load at all — is the tension developed inside the bolt itself, called preload or clamping force. Torque is just the thing a mechanic or technician actually applies and measures at assembly. It is not the same quantity, and it is only an approximate, friction-dependent way of getting to a target preload.