Captive Hex Socket Head Cap Screw

Product introduction

Cylindrical head hexagonal non-shedding screws, also known as "knurled screws" or "non-shedding screws", are fasteners specially used on precision equipment that require frequent disassembly, but the screws cannot completely separate from the mother body. Its design feature is that a freely rotating elastic retaining ring or a preset knurled ring is installed on the screw. After installation, when the screw is loosened to the limit, the retaining ring will snap into place with the connector structure, allowing the screw head to hover without falling off, thereby preventing loss and misalignment, and simplifying maintenance operations in narrow spaces. This product is widely used in fields such as aerospace, communication equipment, industrial machinery and automated production lines that require extremely high maintenance efficiency and reliability, effectively improving the maintainability and operational safety of the equipment.

 

Product Features

1. Core anti-falling function: Its biggest feature is that the screws will not completely fall off from the mounting plate when loosened. The head of the screw is always retained on the base body through the restriction of the screw by the snap ring, retaining ring and other structures, effectively preventing the screw from being lost or falling into the equipment during frequent disassembly and maintenance.

2. Facilitates maintenance in narrow spaces: In situations where space is limited and it is difficult to reach the screw placement point with hands or tools, this design ensures that the screws are always in an operable position, greatly facilitating disassembly and reinstallation, and significantly improving maintenance efficiency and work safety.

3. High-strength fastening and reliable torque transmission: It adopts a cylindrical head hexagonal design, which has a larger contact area with the hexagonal wrench, and can withstand much higher tightening torque than cross-recessed and slotted recesses, providing firm clamping force, effectively avoiding slippage, and making the connection reliable.

4. Compact structure and stable performance: The cylindrical head design is lower than the hexagonal head, saving installation space. Its anti-falling components are usually installed firmly and are not easily displaced due to vibration, and their performance is long-lasting and reliable.

5. Improve the integrity and safety of the equipment: By preventing the accidental falling off and loss of small parts (screws), it not only ensures the integrity of the equipment itself, but also completely eliminates the risk of serious secondary failures such as short circuits and jamming caused by screws falling into precision equipment.

 

Product application

1. Aerospace and defense equipment: widely used in aircraft skin inspection covers, radar casings, airborne equipment, etc. In environments with strong vibration and narrow maintenance space, it can effectively prevent screw loss and ensure maintenance efficiency and flight safety.

2. Industrial automation and robots: It is often used in parts such as robot joint guards, transmission system covers, and inspection doors of assembly line equipment that need to be opened regularly for debugging, replacement, or maintenance, greatly simplifying the maintenance process.

3. Communications and electronic equipment: used in cover fixing of server cabinets, base station antennas, large switches and other equipment. When working above dense cables and precision components, prevent screws from falling off and causing short circuits or equipment damage.

4. Rail transit and automobile manufacturing: used for control boxes, panels and engine room access openings of trains or heavy vehicles. Strong vibration will not cause it to loosen and fall, ensuring safe operation and facilitating quick maintenance on the way.

5. Precision instruments and medical equipment: In expensive and precise instruments such as CT machines and semiconductor manufacturing equipment, any tiny foreign matter may cause malfunctions. Not taking out the screws fundamentally eliminates the risk of the screws accidentally falling into the device.

 

FAQ

Q: How does this kind of screw achieve the effect of "not coming out"?

A: The core is to process an annular groove at a specific position of the screw and install a circlip that can rotate freely but cannot fall off. When the screw is passed through the mounting plate and tightened, this retaining ring will be blocked by the plate surface, so that when the screw is loosened, its head hovers over the plate surface without completely detaching.

 

Q: Can this screw be disassembled and reused?

A: Yes. This is one of its main design purposes. Its anti-fallout structure is permanent, allowing for multiple disassembly and installation without affecting its "non-fallout" function. However, it is necessary to regularly check whether the elasticity of the retaining ring is fatigued or whether the screw thread is worn.

 

Q: Is its anti-loosening performance different from that of ordinary screws?

A: The "non-extrusion" function itself does not directly provide additional thread anti-loosening capabilities. Its purpose is to prevent the screw from completely detaching from the mounting plate. If it is necessary to prevent loosening in a vibrating environment, it must rely on the pretightening force of the screw itself, or use anti-loosening washers, apply thread locking agent, etc. to achieve this. Some models can also be combined with glued anti-loosening threads to form a composite solution.

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