Common methods to prevent screw loosening:

1. Friction Locking

• Spring washers: Use elastic force to increase friction
• Double nuts: Main and auxiliary nuts locked together
• Self-locking nuts: Nylon insert increases friction

2. Mechanical Locking

• Cotter pins: Used with slotted nuts
• Tab washers: Bent to lock nuts
• Wire locking: Multiple screws wired together

3. Permanent Locking

• Spot welding: Weld nut to bolt
• Punching: Thread deformation
• Adhesives: Thread locking compounds (e.g., anaerobic)

4. Structural Locking

• Tang thread: Special thread structure
• Wedge locking: 30° wedge ramp
• Spiralock thread: Improved thread design

Selection Guide:

• General vibration: Spring washer or self-locking nut
• Strong vibration: Mechanical locking + adhesive
• No disassembly needed: Permanent locking
• Frequent disassembly: Structural locking