Non-Standard Blackened Cross-Step Screws

Product introduction

This product is a typical custom-made non-standard screw. The head adopts a cross-recessed design to facilitate precise driving; the shaft is equipped with a precision step structure to achieve axial limit and prevent over-twisting. As a special head screw, its surface is blackened to make it uniform, beautiful and non-reflective. The products are made of carbon steel or alloy steel with strict dimensional tolerances. They are precision electronic screws and are widely used in precision electronic equipment such as smartphones, laptops, and optical instruments. As non-standard fasteners, we provide flexible customization services for special-shaped fastener parts. The step position, head shape, and thread specifications can all be customized according to drawings. Supports small batch samples and large batch supply, welcome to inquire about drawings.

 

Product features

Cross-recessed drive: The cross-recessed type bears even force, has a high screwdriver fit, is not easy to slip, and is suitable for high-precision assembly operations;

Step structure: The shaft is equipped with precision steps, which can achieve axial positioning during installation to prevent screws from being over-tightened or locked too deeply. It is especially suitable for limit connections of multi-layer boards or precision components;

Blackening surface treatment: Using high-temperature blackening or room-temperature blackening process, a dense ferric oxide film is formed on the surface, which has a certain anti-rust ability and is non-reflective. It is suitable for optical and electronic equipment;

Precision dimensional control: As precision electronic screws, their dimensional tolerances are strictly controlled to ensure reliable assembly in tiny electronic devices;

Diversified head shapes: Can be matched with various head shapes such as flat head, round head, pan head, countersunk head, etc. to adapt to different assembly space and appearance requirements.

 

Materials and application fields

Carbon steel (10#, 45#, 35K, 10B21, etc.): good comprehensive mechanical properties, uniform and beautiful surface after blackening treatment, suitable for general industrial scenes;

Alloy steel (SCM435, etc.): can be heat treated to high strength grades (grade 8.8, grade 10.9, grade 12.9), suitable for high-strength connection scenarios;

Stainless steel (304, 316, etc.): has excellent corrosion resistance and is suitable for humid or corrosive environments (if a black appearance is required, black titanium or stainless steel blackening process can be used);

Surface treatment: blackening treatment (blackening at high temperature, blackening at normal temperature), which can be combined with oiling or sealing treatment to enhance anti-rust ability.

 

Application areas:

Precision electronics: application scenarios of precision electronic screws such as smartphones, tablets, digital cameras, laptops, etc.;

Optical equipment: internal limit fastening of optical instruments such as cameras, projectors, microscopes, etc.;

Medical equipment: surgical instruments, diagnostic equipment, monitors and other equipment that require high precision;

Communication equipment: internal structural connections such as routers, base station equipment, and fiber optic terminals;

Instrumentation: precision assembly of measuring instruments, analytical instruments, and control panels;

Automotive electronics: Fastening of electronic modules such as car navigation, driving recorders, and central control panels.

 

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;

Dimensional accuracy control: Key dimensions (cross groove size, head diameter, step diameter, step length, shaft diameter, thread accuracy, total length) are fully inspected or AQL sampled using professional measuring tools such as image measuring instruments, tool microscopes, and pass-and-stop gauges to ensure the tolerance requirements of precision electronic screws;

Step accuracy control: The step length and diameter tolerance can be controlled within ±0.05mm to meet precision limit requirements;

Cross recess precision control: The groove size and depth are measured using special gauges to ensure the accuracy of matching with the screwdriver;

 

Blackening quality control:

Appearance inspection: The surface is uniformly black, without spots or rust;

Film thickness detection: the oxide film thickness is uniform;

Corrosion resistance test: Neutral salt spray test and copper sulfate drop test verify the quality of the blackened layer;

Mechanical property testing: including tensile strength, hardness, and torque testing to ensure that the performance levels specified by the customer are met;

System certification: The company has passed ISO 9001 quality management system certification. The electronics industry can meet the IECQ QC 080000 hazardous substance process management requirements, ensuring that each batch of non-standard fasteners has complete traceability and complies with RoHS environmental standards.

 

Customized services

Size customization: Thread specifications (metric M1.0~M10, English, American), step diameter, step length, shaft diameter, and total length can all be customized according to customer drawings or samples;

Head type customization: As special head screws, special head shapes such as flat head, round head, pan head, countersunk head, large flat head, spherical head, etc. can be customized;

 

Step structure customization:

Single step: realize single point limit;

Multi-step: realize multi-point limit or different diameter matching;

Special-shaped steps: elliptical, square and other non-circular steps to achieve anti-rotation function;

Cross groove customization: The groove size and depth can be customized according to the assembly tools;

Material and performance level customization: carbon steel, alloy steel, stainless steel are selected according to strength, corrosion resistance and other requirements, and the performance level covers 4.8 to 12.9;

Customized surface treatment: black surface treatment such as black zinc, black nickel, black titanium, Dacromet black, etc.;

Packaging method: Anti-static packaging, tape packaging, customized labels, bulk or pallet packaging can be provided to meet the needs of SMT automated assembly lines.

 

FAQ

Q: What are step screws? How is it different from ordinary screws?

A: Step screws are equipped with step structures with different diameters on the shaft. When installed, the steps are against the surface of the workpiece to achieve axial limit; while ordinary screws have equal-diameter shafts and have unlimited positioning functions. Therefore, step screws are special head screws that provide reliable positioning solutions for precision assembly.

 

Q: Is this screw a standard part?

A: No. Step screws are non-standard fasteners. There are no unified standard specifications on the market. They need to be customized and produced according to the customer's specific size, step position, head shape and other requirements.

 

Q: What is the anti-rust ability of blackening treatment?

A: The oxide film formed by the blackening treatment has a certain anti-rust ability, but it is not as good as galvanizing. Suitable for indoor dry environments. If you need higher anti-rust requirements, you can apply anti-rust oil after blackening or choose black zinc or black nickel treatment. As customized non-standard screws, we can recommend suitable surface treatment solutions based on the use environment.

 

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 molding process, it is recommended that the minimum order is 5,000-10,000 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 7–15 working days for small batch customization, and about 15–25 working days for large batch orders depending on the specific quantity. If a new mold is needed, an additional 7-10 days of mold production cycle is required.

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