Overtightening

Overtightening is the application of more torque than specified or required to a threaded fastener, clamp, or seal. It can occur in automotive, industrial, plumbing, and consumer electronics assemblies where bolts, screws, or nuts are tightened beyond their intended clamping load.

Common causes include misreading or ignoring torque specifications, using impact tools or adapters without a torque setting, applying lubrication that is not approved for the joint, or selecting a fastener size or material that cannot safely reach the required load. Cross-threading or misalignment can also create stress concentrations that increase the risk of overtightening.

Consequences include damaged threads (stripped or cross-threaded), stretched or sheared bolts, deformed holes or bearing surfaces, cracked housings or seals, leaks at gasketed joints, and in critical applications, sudden joint failure. Overtightening can compromise structural integrity, reduce clamping efficiency, and impair component life.

Prevention and mitigation involve following exact torque values, using a calibrated torque wrench or torque-limiting tool, observing lubrication guidelines, inspecting fasteners and mating surfaces for damage, replacing compromised parts, and avoiding reuse of damaged bolts. Correct tightening sequences and, where appropriate, the use of torque-to-yield bolts with controlled procedures help prevent over-tightening. Understanding the correct procedure reduces the risk of overtightening and its associated failures.