Stepped shear bolts

Cold heading process is one of the new processes for pressure machining of less or no cutting
metal. It is a processing method that utilizes the plastic deformation of metal under the action of
external forces, and with the aid of molds, redistributes and transfers the volume of metal to form
the required parts or blanks. The cold heading process is most suitable for producing standard
fasteners such as bolts, screws, nuts, rivets, and pins.etc

Stepped shear bolts are specialized fasteners designed to provide controlled shear failure under specific load conditions, often used in structural or mechanical applications where safety and predictable failure points are critical. Here’s a detailed description:

Key Features of Stepped Shear Bolts:

1. Stepped Shaft Design

   • The bolt has a reduced-diameter section (shear groove) along its shank, creating a deliberate weak point.

   • This step ensures the bolt shears at a predetermined load, protecting other components from damage.

2. Material & Strength

   • Typically made from high-strength steel (e.g., Grade 5, Grade 8, or alloy steel) to ensure consistent shear performance.

   • Heat-treated for precise shear strength.

3. Head Types

   • Available in various heads (hex, socket, round) depending on application needs.

   • Some designs include a breakaway head that snaps off after proper installation torque.

4. Thread Type

   • May feature full or partial threading, with the shear step located in the unthreaded portion to avoid thread distortion during shearing.

5. Shear Load Control

   • The stepped section is engineered to fail at a specific shear force, acting as a mechanical fuse.

   • Used in safety-critical systems (e.g., aircraft, machinery, structural joints) to prevent overload.

Applications:

• Structural Engineering: Shear-critical connections in steel frameworks.

• Aerospace: Shear pins in flight control systems.

• Automotive: Suspension or drivetrain components.

• Industrial Machinery: Overload protection in couplings or gearboxes.

Advantages:

• Predictable Failure: Prevents catastrophic damage by shearing at a set load.

• Easy Replacement: Broken bolts can be quickly replaced post-failure.

• Corrosion Resistance: Often coated (e.g., zinc, cadmium) for durability.

Example Use Case:

In a wind turbine, stepped shear bolts may secure the blade hub. If excessive force occurs (e.g., storm winds), the bolts shear, protecting the rotor assembly from severe damage.