Dakro Countersunk Square Neck Bolts

Product introduction

Dacromet countersunk head square neck bolt is a high-performance fastener that combines excellent rust resistance and excellent anti-rotation performance. Its core advantage first comes from the "Dacromet" surface treatment process. This process forms a protective film overlapping with zinc and aluminum flakes on the surface of the substrate, providing corrosion resistance several times higher than that of traditional electroplated zinc. It is especially resistant to acids and alkali and has no risk of hydrogen embrittlement. It is very suitable for harsh environments such as automobiles, bridges, and outdoor facilities. Structurally, it combines the two major designs of "countersunk head" and "square neck". The countersunk head design allows the head of the bolt to sink completely into the workpiece after tightening, ensuring a smooth and smooth installation surface. The key square neck structure forms a square clamping position under the bolt head, which can be tightly embedded in the pre-drilled hole during installation, effectively preventing the bolt from rotating during the tightening of the nut, which greatly improves installation convenience and connection reliability.

 

Product features

1. Excellent corrosion resistance: This is its most significant feature. Using the "Dacromet" (chromium-free zinc-aluminum coating) process, the zinc and aluminum flakes in the coating provide excellent physical barrier and cathodic protection. Its anti-rust ability is more than 7-10 times that of traditional galvanizing, and it can effectively resist salt spray, acid and alkali and other chemical corrosion. It is especially suitable for coastal areas, high humidity and chemical environments.

 

2. Excellent anti-rotation performance: The "square neck" design of the bolt shank is the key. When installed, the square neck section fits into a pre-punched or drilled square hole. This can effectively prevent the bolt from rotating when the nut is tightened, making it easy for one person to operate, greatly improving the installation efficiency and convenience.

 

3. Flat installation interface: The "countersunk head" design allows the head of the bolt to be fully embedded below the surface of the workpiece without protruding after tightening. This not only provides a smooth, flat installation appearance, but also avoids interference on moving or conveying parts, resulting in greater safety.

 

4. No risk of hydrogen embrittlement, high bonding strength: The Dacromet treatment process does not involve electroplating reactions, so it completely avoids "hydrogen embrittlement", a fatal threat to high-strength fasteners, ensuring the safety and reliability of the product. The coating has strong bonding force with the base metal and is not easy to fall off during installation or stress.

 

5. Higher strength foundation: The bolt body is usually made of high-quality carbon steel or alloy steel, with a performance level of up to 8.8 and above, which provides solid mechanical performance support and ensures the strength of the connection structure.

 

Product application

1. Outdoor infrastructure and steel structures: Application scenarios: highway guardrails, transmission towers, communication base stations, bridge components, outdoor lighting poles. Application advantages: Excellent weather resistance and salt spray corrosion resistance, it can withstand the erosion of wind, rain, ultraviolet rays and industrial atmosphere for a long time, ensuring structural safety. The square neck design prevents the bolts from loosening, and the countersunk head ensures smooth connections.

 

2. Automotive industry and transportation: Application scenarios: automobile chassis connectors, bus/truck body frames, container fixings, and rail vehicle components. Application advantages: It can effectively resist the strong corrosion of winter snowmelt and road salt, and its non-hydrogen embrittlement properties ensure the safety of high-strength connections. Anti-rotation feature facilitates installation in tight spaces.

 

3. Mechanical equipment and protective shells: Application scenarios: outer cover panels of agricultural machinery and construction machinery, ventilation duct connections, and sheet metal shells of large equipment. Application advantages: The countersunk head design ensures that the surface of the equipment is flat and has no bulges, avoiding the risk of hooking and having a simple appearance. Excellent anti-corrosion ability adapts to various field operating environments.

 

4. Building curtain walls and metal roofs: application scenarios: fixing and connecting aluminum alloy curtain walls and metal roof panels. Application advantages: The countersunk head design meets the aesthetic requirements of the building's appearance and ensures a smooth and smooth facade. Dacromet treatment provides protection against corrosion for decades, far exceeding that of ordinary galvanized parts.

 

FAQ

Q: What is the core advantage of this bolt?

A: It combines three core advantages:

1. Super anti-corrosion: Dacromet treatment provides excellent salt spray, acid and alkali resistance, and the anti-rust life is 7-10 times that of traditional galvanizing.

2. Effective anti-rotation: The unique square neck design is embedded in the base body during installation to prevent the bolt from rotating when tightening the nut. It can be operated by one person.

3. Smooth and beautiful: The countersunk head design makes the head flush with the surface of the workpiece after installation, with good streamline shape and no interference.

 

Q: Why is it more rust-proof than ordinary galvanized bolts?

A: Ordinary galvanizing is anodic protection and consumes quickly. Dacromet coating is an inorganic film layer superimposed on zinc and aluminum flakes. It has the dual functions of physical shielding and cathodic protection. It is denser, so the corrosion resistance life is greatly extended, and there is no risk of hydrogen embrittlement.

 

Q: Can this bolt be reused?

A: Reuse is not recommended. The main reasons are: the square neck may be slightly deformed after being embedded in the square hole for the first time, and the anti-rotation effect will be reduced during the second installation. Disassembly and retightening will cause wear to the Dacromet coating and affect its anti-corrosion effect. The pretightening force of the bolt has reached the design value when tightened for the first time, and repeated use poses safety risks.

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