Non-Standard Semi-Round Colored Paint Carriage Screws

Product introduction

This product is a typical non-standard screw with a semicircular or mushroom head design and a square neck underneath. It is embedded into the connected piece during installation to effectively prevent the nut from rotating and achieve unilateral locking. As a special-shaped screw, its surface is treated with color zinc plating, giving it a golden appearance and excellent anti-corrosion and decorative effects.

The products are made of high-quality carbon steel or alloy steel and can provide various strength levels from 4.8 to 10.9. They are widely used in furniture manufacturing, construction hardware, vehicle assembly and other scenarios. We specialize in customized non-standard screw solutions. Size, head shape, square neck specifications, and surface treatment can all be customized according to drawings. Supports small batch samples and large batch supply, welcome to inquire about drawings.

 

Product design and features

Color-plated carriage screws are a type of fastener with a unique head shape. The head is in the shape of a semicircular head or a mushroom head, with a square neck or toothed flange underneath. During installation, the square neck is embedded in the connected parts to achieve self-locking and anti-rotation functions. The surface is treated with color zinc plating, giving it a bright golden appearance.

 

This product is a typical non-standard screw. Its main features include:

Unique head shape: semi-circular head or mushroom head design, the surface is round and beautiful after installation, and will not scratch objects or people;

Square neck anti-rotation structure: There is a square neck or toothed boss under the head, which is embedded in the wood or metal slot during assembly to prevent the screw from rotating with the nut and achieve unilateral locking;

Colored zinc plating surface treatment: bright and uniform color, excellent anti-corrosion performance and decorative effect, in line with RoHS environmental protection requirements;

Optional self-tapping performance: The self-tapping tooth profile can be configured according to needs, and can be directly used on soft materials such as wood and plastic without pre-tapping threads.

As a special-shaped screw, its appearance and function break through the design concept of traditional fasteners and are widely used in various scenarios that require one-sided installation.

 

Materials and application fields

Color-plated carriage screws are made of high-quality carbon structural steel or alloy steel. The material characteristics are as follows:

Carbon steel (10#, 45#, 35K, etc.): has good comprehensive mechanical properties and is suitable for general industrial scenarios;

Alloy steel (10B21, SCM435, etc.): can be heat treated to high strength grade, suitable for high load connections;

Surface treatment: Colored zinc plating (yellow zinc) treatment, salt spray test up to 48-120 hours, with both anti-corrosion and decorative functions.

 

As non-standard screws, they have a wide range of applications:

Furniture manufacturing: used for connecting wooden furniture, offices and chairs, the square neck can effectively prevent loosening;

Building hardware: such as door and window installation, guardrail fixing, steel structure connection, etc.;

Mechanical equipment: used for fastening equipment shells and panels, the semi-circular head design is beautiful and safe;

Vehicle manufacturing: connection and fixation of carriage panels, agricultural machinery and equipment, and special vehicles;

Outdoor facilities: fastening of outdoor wooden or metal structures such as park chairs, billboards, fences, etc.

 

Quality control and certification system

Since the color-plated carriage screws are customized non-standard screws, their production process implements a strict customized quality control system:

Raw material control: All carbon steel and alloy steel materials come with material certificates to ensure that the chemical composition meets standard requirements;

Dimensional accuracy control: Key dimensions (head diameter, head height, square neck size, thread specification, total length) are fully inspected or AQL sampled using professional measuring tools such as image measuring instruments, projectors, pass-and-stop gauges;

Mechanical property testing: including tensile strength, yield strength, hardness, and torque testing to ensure that the performance levels specified by the customer are met (level 4.8, level 8.8, level 10.9, etc.);

Surface quality inspection: The thickness, adhesion, salt spray test, etc. of the colored zinc plating layer are carried out according to standards to ensure stable anti-corrosion performance;

Anti-rotation function verification: Each batch of products is tested for assembly of the square neck and mating hole to ensure reliable anti-rotation effect;

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 screws has complete traceability.

 

Customized services

We focus on providing customers with customized non-standard screw solutions. The customization range of color-coated carriage screws includes:

Size customization: head diameter, head height, square neck size, thread specifications (metric, imperial, American), and total length can all be customized according to customer drawings or samples;

Head type customization: optional semi-round head, mushroom head, large flat head, head with gasket, etc.;

Square neck customization: The size, length, and position of the square neck can be adjusted according to assembly requirements, or it can be changed to a toothed flange or knurled structure;

Thread form: machine threads, self-tapping threads, high and low threads, etc. can be designed to meet the needs of different base materials;

Performance level customization: According to strength requirements, different performance levels such as level 4.8, level 8.8, level 10.9, and level 12.9 can be provided;

Surface treatment customization: In addition to color zinc plating, we can also provide blue zinc plating, white zinc plating, black zinc plating, Dacromet, hot dip galvanizing and other options;

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

Whether it is small batch sample verification or large batch stable supply, we can respond quickly to ensure that each customized non-standard screw accurately matches the customer's assembly process and usage environment.

 

FAQ

Q: Why are carriage screws called "carriage screws"?

A: Carriage Bolt originated from the fastener used to connect the wooden body and metal parts in early carriage manufacturing. Its square neck design prevents it from rotating with the nut during installation. This name is still used today. This product is a non-standard screw and can be customized to different specifications according to needs.

 

Q: What is the function of the square neck?

A: The square neck is the core design of carriage screws. When installed, the square neck is embedded in a pre-slotted hole in wood or metal. When the nut is tightened, the square neck prevents the screw from rotating, allowing one-sided operation to complete the locking. This makes it typical of specially shaped screws.

 

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 forming process, it is recommended that the minimum order is 50,000-10,000 pieces; when using CNC turning or centering machine processing, 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 mold opening is required, an additional 7-10 days of mold production cycle is required.

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