Non-Standard Hexagonal Double-Headed Screws

Product introduction

This product is a typical custom-made non-standard screw with precision threads on both ends and a hexagonal head in the middle for easy wrench operation and two-way tightening. The thread specifications at both ends can be the same or different to meet the needs of equal or variable diameter connections.

As special head screws, the products are made of alloy steel or carbon steel. They can reach high strength levels of 8.8-12.9 after heat treatment. The surface can be galvanized or blackened as required. They are widely used in automotive engine brackets, suspension systems, mechanical equipment and other scenarios. They are an important component of automotive parts fasteners.

We specialize in customizing non-standard fasteners. Thread specifications, hexagonal head sizes, and length ratios can all be customized according to drawings. As customized special shape fastener parts, we support small batch samples and large batch supply. Welcome to inquire about drawings.

 

Product design and features

Double-headed thread design: Both ends are equipped with precision threads, which can connect two workpieces respectively to achieve two-way fastening; the thread specifications at both ends can be the same or different to meet the needs of reducing diameter connections;

Middle hexagonal head: The hexagonal head provides a wrench focusing point, making it easy to use a standard wrench for installation and removal without the need for special tools; at the same time, the hexagonal head can be used as a limit surface to prevent over-tightening of the screws;

Headless or fully threaded optional: can be designed as a double-headed stud without a hexagonal head in the middle, or with a fully threaded structure at both ends according to requirements;

High-strength load-bearing: The whole is made of high-strength materials, which can reach level 8.8, 10.9 or 12.9 after heat treatment to meet the needs of heavy-duty connection;

Diversified thread configuration: Both ends can be configured with the same thread (equal-diameter double-head) or different threads (reducing-diameter double-head). Special thread forms such as left-hand thread and fine thread can also be customized.

 

Materials and application fields

Alloy steel (40Cr, 35CrMo, SCM435, SCM440, etc.): It has excellent comprehensive mechanical properties and can reach strength requirements of grade 8.8 to grade 12.9 after heat treatment. It is an ideal material for manufacturing automotive parts fasteners and industrial equipment;

Carbon steel (10B21, 35K, 45#, etc.): suitable for strength requirements of grade 8.8 and below, economical cost;

Stainless steel (304, 316, 410, etc.): suitable for corrosive environments, such as chemical equipment, marine engineering, medical equipment, etc.;

Surface treatment: zinc plating, nickel plating, blackening, Dacromet, Jumet, passivation and other treatments can be provided according to demand.

As a non-standard fastener, it has a wide range of applications, especially suitable for scenarios that require two-way connections or where space is limited:

Automobile manufacturing: key connectors in automotive parts fasteners such as engine mounts, suspension systems, gearbox connections, etc.;

Mechanical equipment: motor mounting seats, bearing seats, reducer connections and other parts that require two-way fastening;

Building steel structure: steel beam connections, curtain wall hangings, and tie-fastening of earthquake-resistant brackets;

Petrochemical industry: pipeline flange connection, valve installation, pressure vessel fastening;

Rail transit: carriage connectors, bogie fastening, track fastener systems;

New energy: wind power tower bolt connection, photovoltaic bracket fastening, battery module connection.

 

Quality control and certification system

Raw material control: All materials are accompanied by material certificates, and the composition is verified by a spectrum analyzer to ensure compliance with standard requirements;

Heat treatment control: A continuous mesh belt furnace is used for quenching + tempering treatment, and the temperature and time are strictly controlled to ensure that the hardness and tensile strength meet the design grade requirements;

Dimensional accuracy control: Key dimensions (thread specifications at both ends, thread length, hexagonal head across sides, hexagonal head thickness, total length) are fully inspected or AQL spot-checked using professional measuring tools such as image measuring instruments, thread gauges, pass-and-stop gauges;

Thread accuracy control: Thread accuracy at both ends is strictly controlled to ensure the reliability of meshing with mating parts;

Coaxiality control: The coaxiality of the threads at both ends and the hexagonal head is tested using professional inspection tools to ensure smooth installation;

Mechanical property testing: tensile strength, yield strength, hardness, guarantee load test;

System certification: The company has passed ISO 9001 quality management system certification, and automotive products can meet the requirements of IATF 16949, ensuring that each batch of non-standard fasteners has complete traceability.

 

Customized services

Size customization: Thread specifications at both ends (metric M3-M36, English, American), thread length at both ends, hexagonal head dimensions across sides, hexagonal head thickness, and total length can all be customized according to customer drawings or samples;

Head type customization: As special head screws, in addition to standard hexagonal heads, special head types such as hexagonal flange heads, twelve-head heads, and hexagonal heads with gaskets can also be customized;

 

Thread configuration customization:

Equal diameter double head: the thread specifications at both ends are the same;

Reducing double head: The thread specifications at both ends are different to achieve variable diameter connection;

Special threads: left-hand thread, fine thread, trapezoidal thread, sawtooth thread, etc.;

Partial thread: only partially threaded at both ends, with a polished rod in the middle;

Customized hexagonal head structure: through-hole hexagonal head, blind hole hexagonal head, hexagonal head with pin hole, hexagonal head with slot;

Material and strength level customization: carbon steel, alloy steel, stainless steel can be selected according to the use environment, and the performance level covers 4.8 to 12.9;

Customized surface treatment: galvanized, nickel plated, blackened, Dacromet, Jiumet, phosphating, hot-dip galvanized, etc.;

Packaging method: Bulk, bagged, pallet packaging, and customized labels can be provided to meet the needs of different assembly lines.

 

FAQ

Q: What is the difference between hexagonal double-headed screws and ordinary double-headed studs?

A: Ordinary double-headed studs have threads at both ends and no hexagonal head in the middle. Two nuts need to be tightened during installation. Hexagonal double-headed screws have a hexagonal head in the middle and can be tightened directly with a wrench without the need for auxiliary nuts. The installation is more convenient and the disassembly is faster. Therefore, this product is a special head screw, which significantly improves assembly efficiency.

 

Q: Can the threads on both ends be different?

A: Yes. This is an important customization feature of this product. For example, one end is M10 threaded and the other end is M12 threaded to achieve variable diameter connection; or one end is coarse threaded and the other end is fined threaded to meet different matching requirements.

 

Q: How to ensure the coaxiality of the threads at both ends?

A: We adopt precision machining technology, strictly control the processing standards, and use coaxiality inspection tools to randomly inspect each batch of products to ensure that the coaxiality of the threads at both ends and the hexagonal head is within the allowable tolerance range, and the installation is smooth and free of jamming.

 

Q: As a customized non-standard screw, what is the minimum order quantity?

A: The minimum order quantity depends on the complexity of the product and the production process. When using the cold heading + thread rolling process, it is recommended that the minimum order is 5,000-10,000 pieces; when using the CNC turning + thread rolling process, small batch customization of several hundred pieces can be supported.

 

Q: How long is the production cycle generally?

A: It usually takes 10-20 working days for small batch customization, and about 20-30 working days for large batch orders depending on the specific quantity. If a new hexagonal head mold or special thread tool is needed, an additional 10-15 days of tooling production cycle will be required.

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