Metal Shed Screws

The head drive structure of Metal Shed Screws has been optimized and designed. The height and opposite-side distance of its hexagonal flange head are based on ISO 898-1 tolerance requirements for fastener geometric dimensions. Under the ST5.5 specification, the deviation of the opposite-side distance is controlled within plus or minus 0.2 mm, ensuring a stable fit with a standard socket wrench and avoiding slipping caused by excessive fit clearance. The neck of the screw is equipped with an annular stress relief groove. This design allows the torsional stress concentration point generated during the tightening process to be transferred from the thread root to the neck. According to the test method for torsional strength of fasteners in Part 26 of DIN 267, the breaking torque of screws with stress relief grooves is approximately 15% higher than that of non-grooved structures. Under the M6 ​​specification, the measured breaking torque reaches 8.5 Nm, and the safety factor is increased to 2.2 times. After installation, the fit between the lower edge of the screw head flange and the surface of the plate directly affects the anti-loosening performance of the connection. According to the lateral vibration test method, after 25,000 cycles at a frequency of 20 Hz and an amplitude of 2.5 mm, the residual pre-tightening force retention rate of the screw with a stress relief groove design still reaches 86% of the initial value, which is about 10 percentage points higher than the conventional structure.

 

 

In an environment of alternating temperatures, the difference between the thermal expansion behavior of metal shed screws and the connecting plates affects the preload stability. According to ASTM E228 thermal expansion coefficient measurement method, the linear expansion coefficient of carbon steel screws is about 11.7 microns per meter per Kelvin, while the matching galvanized steel plate is about 12.2 microns per meter per Kelvin. The difference between the two is when the ambient temperature rises from minus ten degrees Celsius to forty degrees Celsius. For a screw with a length of 30 millimeters, the thermal elongation difference between it and the plate is about 4.5 microns. This small difference can be compensated by the elastic elongation of the screw itself, and there is no need to worry about the significant attenuation of the preload force. When used in coastal high-humidity areas, the anti-corrosion system of screws should include a zinc-aluminum composite coating. According to the ISO 9227 copper accelerated acetic salt spray test, the coating has no white rust on the surface and no red rust on the matrix after eight hundred hours of exposure. At the same time, in the thermal shock test from -20 degrees Celsius to 60 degrees Celsius, the coating adhesion still maintains level 4B according to the ASTM D3359 cross-hatch method after one hundred complete cycles, indicating that it has excellent thermal stress peeling resistance. The tip drill edge of the screw can still maintain the ability to be reused at least five times after penetrating a double-layer metal plate. It was measured that after five screws of the same specification continuously penetrated a 2.0 mm thick galvanized plate, the drilling time only increased from the initial 3.2 seconds to 3.8 seconds. The performance degradation was controlled within 20%, which fully met the actual need to replace screws due to misoperation during on-site construction.

 

 

 

 

 

 

JOYEAR provides high-volume, highly efficient export solutions for industrial components to clients worldwide. Our custom metal products are expertly crafted. If you send us your design files, whether they are digital drafts or prototypes, our talented team will precisely create tangible parts that satisfy your requirements.

★ Our product range includes:

► Materials: Carbon steel / Mild steel / Structural steel / Stainless steel / Aluminum / Copper, etc.

► Forms: Sheets / Profiles / Tubes / Round bars / Flat bars / Square bars, etc.

 

 

Obtain drawings from clients or produce drawings based on their samples or specifications.

The drawings, product raw materials, surface treatment, and other details are attested to by both parties.

 

 

 

 

 

Provide a quote, confirm the order quantity, and include all relevant information.

Like the terms of payment, the terms of trade, the kind of packaging, etc.

 

 

 

When manufacturing the goods, adhere precisely to the original drawings and samples.

After a final inspection, it was meticulously packaged and delivered to the customers.

 

 

 

 

 

 

 

 

 

 

 

 

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