Weekly Science Popularization -- Twisting Nut

Release Time:

Jul 11,2025

Weekly Science Popularization -- Twisting Nut

NUTS - Twist off Anti-theft Nut

The core of the principle of twisting a nut is to preset a weak point (such as a plum blossom head or a specific neck), and when the torque reaches the design value, use the material shear force to break the part, thereby ensuring that the bolt reaches the specified pre tightening force and preventing loosening.

Design principles
Weak point preset: Twisted nuts are usually designed with a tapered area at the end of the bolt, such as a plum blossom head or neck, to weaken their cross-sectional size through precise calculation and match their shear strength with the target pre load force. ‌‌
Mechanical control

When torque is applied, the bolt shaft generates axial tension (pre tension), while the weak part simultaneously bears shear stress. When the tensile force reaches the design value, the shear stress exceeds the material limit, causing the predetermined part to fracture. ‌‌
Tool matching

Use a specialized tool (such as an electric torque wrench) to clamp the nut and continuously apply torque until fracture occurs. ‌‌
Dual effect
Confirm the pre tightening force meets the standard through the fracture signal;
Remove excess structures (such as plum blossom heads) to achieve anti disassembly function. ‌‌‌‌
Application scenarios
High strength connection: mainly used in scenarios such as bridges, steel structures, and buildings that require strict bolt pre tightening force. ‌‌1‌‌2
Anti loosening requirement: The dead end design can avoid manual disassembly and improve structural safety. ‌‌

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