Double-Ended Stud Structural Principles and Application Analysis

A double-ended stud, also known as a double-ended screw or stud, is a fastener with threads at both ends and a plain center. Common types in international standards include the double-ended bolt, double-ended threaded stud, double-ended hex bolt, double-ended lag bolt, as well as double-ended machine screws and double-ended socket screws for mechanical equipment.

This type of fastener is widely used in machinery manufacturing, steel structures, bridges, automobiles, energy equipment, and other fields, primarily for securing connections, transferring force, and securing structures. Because nuts can be attached to both ends, they can achieve high-strength connections in thick plates or deep holes while maintaining stability during repeated assembly and disassembly.

A typical stud has a plain center, with the thread length at each end varying depending on the application. Typical types include:

Double-Ended Hex Bolt: A hexagonal structure with threads on both ends, suitable for steel structure connections.

Dual-Head Stud Bolt: Features different thread lengths on both ends, used for mechanical installation or pressure piping systems.

Dual Threaded Screw / Dual End Screw: Features different thread directions on both ends, suitable for quick assembly and disassembly or when special rotation requirements are required.

M10 Double-Ended Dowel Screw: Commonly used in wood structures or machine tool positioning, it offers excellent tensile and shear resistance.

Double-Ended Wing Screw: Features a wing-shaped end, suitable for light-load structural connections requiring quick manual tightening.

These products are collectively referred to as the double-headed stud screw bolt series. They are manufactured according to DIN, ISO, and GB standards, with diameters typically ranging from M3 to M100, and lengths can be customized to meet customer requirements.

Stud bolts have a wide range of applications, including the following common scenarios:

Large Equipment Installation

In equipment such as reducers, mechanical seal seats, and sight glass mounts, one end is threaded into the main body, while the other end is connected to the accessory via a nut. The accessory can be repeatedly removed, and when the thread wears, only the bolt body needs to be replaced, resulting in low maintenance costs.

Thick Plate and Deep Hole Connections

When the connecting parts are thick or require high preload, ordinary bolts cannot meet the requirements. Double-End Threaded Studs can effectively achieve deep tightening.

Steel Structure and Building Connections

Double-Ended Bolts and Double-Ended Lag Bolts provide stable force transmission in steel structure installations such as tower cranes, bridges, roof trusses, and beam suspension systems.

Automobiles and Mechanical Equipment
Double-ended machine Screws and Dual-End Screws are widely used in high-vibration environments such as engine connecting rods, chassis mountings, and transmission supports.

In high-vibration or high-temperature environments, threaded connections are prone to loosening due to frictional loss. Stud bolts are often used with spring washers, nylon locknuts, or anti-loosening adhesive to prevent thread slippage.

For example, in industrial equipment or chemical plants, dual-threaded screws significantly enhance anti-loosening effectiveness by offsetting rotational torque with threads in different directions. Double-ended socket screws, on the other hand, maintain a high locking torque in confined spaces, preventing loosening.

Common materials for stud bolts include:

Carbon steel: Q235, 45#, 40Cr, 35CrMoA, Q345D;

Alloy steel: 25Cr2MoV, B7, B7M, B16;

Stainless steel: 304, 316, 304L, 316L, B8, B8M;

These materials can be classified by strength grade, such as 4.8, 8.8, 10.9, etc. Typical standards include:

GB 900-1988, GB 901-88

ISO 898-1 (Mechanical Properties Standard)

ASTM A193 / A320 (High Temperature and High Pressure Standard)

The High-Strength Double-Ended Bolt series demonstrates excellent strength and fatigue resistance in energy equipment, refinery valves, and bridges.

Stud welding is commonly performed using arc stud welding, which offers the following advantages:

Direct attachment without drilling, riveting, or turning;

Welding can be completed on one side, resulting in minimal deformation and high strength.

Suitable for thin plates, steel structures, and applications requiring high sealing.

Automated mass production is possible, supporting batch welding of dual-head stud bolts and screw bolts.

Precise control is achieved through CNC automatic welding machines or gantry welding systems.

The welded joint strength is typically greater than the stud body strength, offering excellent cost-effectiveness and repeatability.

To ensure corrosion resistance and thread fit accuracy, stud bolts typically undergo the following surface treatments:

Electrogalvanizing/Nickel plating/Chrome plating

Blackening, oxidation, and phosphating

Electroless zinc flake coating (Zn-Flake Coating)

The manufacturing of stud bolts typically includes the following processes:

Raw Material Straightening and Cutting: Steel is cut to the required length using a straightener and cutter.

Thread Rolling: Precision threads are formed using a thread rolling machine, ensuring pitch and profile accuracy.

Heat Treatment and Tempering: Improve tensile strength and ductility;

Thread Inspection and Torque Testing: Ensure fit accuracy and tightening reliability.

During inspection, focus on checking thread integrity, guiding accuracy, and whether the thread profile is deformed. Dual-threaded screws exhibiting cracks, dents, or abnormal thread pitch should be immediately discarded to prevent assembly failure.

During installation, use a torque wrench and tighten to the designed torque value to prevent over-tightening or loosening. Regularly inspect the head and threads of the dual-head stud bolt for wear, and replace the mating nut and stud if necessary.

For high-load equipment such as engines, compressors, or steel structure hoisting devices, the axial clearance and torque variation of the connecting threads should be regularly inspected to ensure the safety and reliability of the overall structure.

The Double-Ended Stud series, with its compact structure, high strength, and easy assembly and disassembly, is widely used in machinery manufacturing, bridge construction, chemical equipment, and energy engineering. Whether it's the Double-Ended Bolt, Double-Ended Lag Bolt, Dual-Threaded Screw, or Double-Ended Socket Screw, they all play an irreplaceable role as core connections in modern industry.

By combining high-strength materials, precision machining, and advanced anti-loosening technology, the Dual-Head Stud Bolt and related series bolts not only meet the needs of efficient assembly but also provide reliable protection for intelligent manufacturing and structural safety.