The Roll Threading Process:

1. Preparation:

• A cylindrical blank (typically slightly smaller than the finished diameter of the thread) is prepared. The material must be ductile enough to deform without cracking, such as alloy steels, stainless steels, or titanium.

2. Thread Rolling Dies:

• Specialized thread rolling dies are used to create the thread profile. These dies can be:

• Flat Dies: Two flat, hardened dies squeeze the blank as it passes between them, forming the thread.

• Cylindrical Dies: Two or three cylindrical dies rotate around the blank to form threads.

• Planetary Dies: Multiple smaller dies rotate around the blank for high-speed production.

3. Thread Forming:

• The blank is fed into the dies, and high pressure is applied to displace the material into the thread shape.

• The process is typically performed at room temperature (cold forming), although warm or hot threading may be used for particularly hard materials.

4. Finishing:

• Threads are inspected for dimensional accuracy,
  pitch, and surface quality.

• Secondary processes, such as coating or heat treatment, may follow.

Why Use Roll Threading for Fasteners?

High Strength and Durability: Threads created by rolling are more resistant to fatigue and wear, making them ideal for critical applications.

Efficiency for Mass Production: Roll threading can produce thousands of fasteners quickly with consistent quality.

Cost Savings: Despite higher initial tooling costs, the reduced material waste and longer tool life make roll threading cost-effective in the long run.

Advantages of Roll Threading:

Stronger Threads: The material’s grain structure is compressed and aligned along the thread, improving strength and fatigue resistance.

Improved Surface Finish: The forming process creates smooth, burr-free threads, reducing stress concentrations.

Efficiency: Roll threading is faster and produces less waste compared to cut threading.

Material Savings: No material is removed, resulting in near-net-shape threads.

Longer Tool Life: Dies used in roll threading typically last longer than cutting tools.

Applications in Engineered Fasteners:

Roll threading is commonly used for fasteners that require strength, durability, and precision. Applications include:

Bolts and Screws: High-strength threaded fasteners for aerospace, automotive, and industrial uses.

Studs and Rods: Threaded rods used in construction, oil & gas, and machinery.

Custom Fasteners: Non-standard or specialty threads for critical applications.

Medical Components: Precision threads for implants or surgical instruments.

Limitations

Material Restrictions: Requires ductile materials that can deform under high pressure.

High Initial Cost: Custom thread rolling dies can be expensive to manufacture.

Limited Thread Profiles: Not all thread geometries can be rolled (e.g., very coarse threads or custom profiles).

Preform Requirements: The blank must be pre-machined to specific dimensions before threading.