Over-Torque

Over-torque is the condition of tightening a fastener beyond the specified or appropriate torque level for the joint. When a bolt or screw is over-torqued, the fastener can be stretched past its elastic range, meaning it will not fully spring back and may be permanently elongated. Over-torque can also damage the threads, deform the screw head or drive recess, crush the clamped materials, or cause the fastener to break during installation.

Over-torque is a problem because it can reduce joint reliability even if the fastener doesn’t snap immediately. A yielded bolt may lose preload over time, making the joint more likely to loosen or fail under vibration and cyclic loads, and damaged threads can lead to stripping during removal or reassembly. Preventing over-torque typically involves using calibrated torque tools, following the correct torque spec for the fastener size, grade, and lubrication condition, and using tightening methods like torque-angle when consistent preload is critical.