Shear bolts black oxide

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

A Shear Bolt with Black Oxide coating is a specialized fastener designed to fail under excessive torque or load, thereby protecting more critical components in a mechanical system. Here’s a detailed description:

1. Material & Construction

• Typically made from medium-carbon steel or alloy steel for strength.

• Heat-treated to achieve a precise shear strength.

2. Black Oxide Coating

• Process: The bolt undergoes a chemical conversion coating (black oxide) that creates a magnetite (Fe₃O₄) layer on the surface.

• Appearance: Matte black finish.

• Benefits:

  • Corrosion Resistance: Improved rust protection compared to bare steel (though not as robust as zinc plating).

  • Reduced Friction: Smoother surface aids in torque consistency.

  • Aesthetic & Low Reflectivity: Useful in applications where glare or visibility must be minimized.

3. Shear Bolt Design Features

• Precision Shear Point: Engineered to break at a specific torque threshold.

• Head Styles: Hex, socket, or specialty heads (depending on application).

• Threads: May be fully or partially threaded, with tight tolerances.

4. Common Applications

• Agricultural Machinery (e.g., tractor PTO shafts).

• Snowblowers & Rotary Cutters (protects drivelines).

• Industrial Gearboxes & Conveyors.

• Aerospace & Automotive Safety Systems.

5. Advantages of Black Oxide Shear Bolts

• Controlled Failure: Sacrificial protection for expensive equipment.

• Cost-Effective: Black oxide is cheaper than many other coatings.

• Dimensional Stability: Coating adds minimal thickness, ensuring fit in tight tolerances.

6. Limitations

• Moderate Corrosion Resistance: Not ideal for highly corrosive environments (e.g., marine applications) unless supplemented with oil or wax.

• Shear Strength Variability: Proper torque calibration is critical.

Alternatives

• Shear Pins (unthreaded, easier to replace).

• Zinc-Plated or Stainless Steel Shear Bolts (for harsher environments).