12-Point Bolt

12-Point Bolts (Double Hex Bolts): Overview

Material:

• Common materials:
  • Carbon steel: Grade 8.8/10.9 for high tensile strength in general and heavy-duty applications.
  • Stainless steel: 304/316 for corrosion resistance in chemical, marine, or high-moisture environments.
  • Alloy steel: ASTM A193 B7/B16 for high-temperature and high-pressure systems (e.g., aerospace, power plants).
• Surface treatments: Zinc plating, Dacromet coating, Xylan® finish, or hot-dip galvanizing for wear and corrosion resistance.

Manufacturing Process:

1. Cold Heading: Forms the 12-point head and shank from steel wire using precision dies to create the double-hexagonal profile.
2. Thread Rolling: Cold-forming threads via dies to enhance strength and fatigue resistance.
3. Heat Treatment: Quenching and tempering (for carbon/alloy steel) to achieve target hardness (HRC 22-34) and tensile strength.
4. Surface Finishing: Electroplating, coating, or passivation (stainless steel) for environmental protection.
5. Quality Inspection: Dimensional checks (head symmetry, thread pitch) and hardness testing.

Key Production Considerations:

• Head precision: Ensure 12-point geometry matches standard sockets (e.g., ISO 10664) for tool engagement.
• Thread consistency: Avoid galling or cross-threading risks with tightly controlled pitch and diameter.
• Material defects: X-ray or ultrasonic testing to detect internal voids or cracks in high-grade alloys.
• Coating adhesion: Uniform coverage to prevent flaking under torque or thermal stress.

Applications:

• Aerospace: Engine mounts, landing gear, and turbine assemblies requiring vibration resistance.
• Automotive: High-performance engines, transmission systems, and suspension components.
• Heavy machinery: Hydraulic systems, mining equipment, and industrial presses.
• Energy sector: Wind turbines, nuclear reactors, and oil/gas drilling rigs.
• Defense: Military vehicles and equipment subjected to extreme conditions.

Installation:

1. Tool selection: Use a 12-point socket or wrench matching the bolt head size (e.g., 10mm, ½”).
2. Thread preparation: Clean threads and apply anti-seize compound if required (avoid on coated bolts).
3. Alignment: Hand-tighten to ensure proper thread engagement and prevent cross-threading.
4. Torque application: Follow manufacturer specifications (e.g., 50–400 Nm for M12–M36 bolts) using a calibrated torque wrench.
5. Post-installation: Inspect for proper seating, and re-torque after initial use if in high-vibration environments.

Note:

• Load capacity: Verify bolt grade and coating compatibility with operational stresses (e.g., thermal cycling, dynamic loads).
• Reuse: Avoid reusing bolts in critical applications if threads or coatings are damaged.
• Safety: Pair with lock washers or thread-locking adhesives in high-vibration systems.

Ideal for engineers and technicians requiring compact, high-torque fasteners in confined spaces or extreme environments.

Key Terms: 12-Point Bolts, Double Hex Bolts, Aerospace Fasteners, ASTM A193, Torque-Resistant Bolts.