Bolt loosening is a major cause of equipment failure in MRO maintenance, especially in vibration, impact and temperature changing environments. This guide provides practical technical instructions on anti-loosening principles, solution comparison and application selection.
Thread loosening is caused by **axial preload loss and tangential micro-slip accumulation**. Effective anti-loosening design includes increasing friction, restricting rotation and chemical locking, with combined application achieving best results.
1. Spring washers: Low cost, elastic anti-loosening; only for light-load, low-frequency vibration, easy to fatigue under heavy load.
2. Anti-loosening nuts (all-metal/nylon): All-metal type is high temperature resistant; nylon type is detachable, suitable for medium vibration equipment.
3. Thread locking adhesive: Fills thread gaps, provides anti-loosening, sealing and rust prevention; medium strength for removable use, high strength for permanent locking.
4. Wedge lock washers: Engaging anti-rotation, flexible disassembly, widely used in outdoor vibration scenarios like PV structures.
1. Light-load low-frequency (electronics): Spring washers + nylon anti-loosening nuts.
2. Medium-load medium-frequency (general machinery): All-metal anti-loosening nuts + thread adhesive.
3. Heavy-load high-frequency (automotive, engineering machinery): Wedge lock washers + high-strength bolts + adhesive.
Installation: Use torque wrench for precise tightening; avoid mixing tools; choose 304/316 stainless steel for outdoor/coastal environments to prevent corrosion.