Captive screws are an engineered class of fastener designed for a permanent hold (captivation) within a target assembly or housing, including upon servicing. They provide a secure joining, and avoid fastener loss or damage that might be caused by a loose part.
Captive screws basically are specially designed to lock into position in a hole, enabling easy setting up and removing of the attached pieces even without the complete removal of the screw. Commonly captive screws are used while manufacturing furniture, computer cases, and other equipment that must be developed on high-volume lines, since they are safer and faster to use compared to the other conventional types, because they do not damage or clog the machinery or fall out.
Most of the captive screws have a hexagonal-head intended for using with the specialized tools. Captive screws come with Philips or standard heads that are designed for usage with drill equipment and ordinary screwdrivers. Captive screws can be found in several configurations and sizes much like the conventional screws premeditated to be utilized for large number of applications. A few captive screws are designed to pivot back or retract to prevent workers being cut or scraped by screws. Slight differences in shank, grooves, or threading may make the switching of different captive-screws inadvisable or difficult, which depends entirely on the application.
Captive screws get snapped into the position with the slightest use of thumb pressure. An aluminium grommet presently retains the screw in a panel to make sure that while disassembling, no loose machinery go missing. The latest range of the captive screws were designed keeping in mind the electronic heat sink applications, to offer high load consistent mechanical fastening which maximizes the thermal conductivity, irrespective of the device’s vibration, shock, and chip thermal-expansion involved.
Invaluable for equipment panels where mounting hardware is subject to loss, these captive screws and retainers assure easy and secure assembly. In addition to standard models, users choose variations such as slotted, unslotted, or hex heads, washers for oval head styles, plus retainer spring and washer sets.
Material Choices
Captive Screws can be custom manufactured from a selection of specialist materials.
Custom Sizes
Captive Screws are available in standard metric and imperial ranges. As standard, metric diameters range from M1.4 up to M12, and lengths range from 6mm up to 300mm. Imperial thread sizes include both UNF and UNC threads, and range in diameter from No.0 all the way up to 1 inch.
Captive Screws are often manufactured to order, meaning that there is often a high degree of customisability in the design process, this means that non-standard dimensions and modifications can usually be made on request.
Installation
Each type of captive fastener becomes a permanent part of the panel or item to which it is installed. This permanent installation eliminates loose hardware problems. Both a self-clinching fastener and a broaching fastener will withstand high push-out and torque-out forces. Weld nuts self pilot into pre-drilled holes and are round, thus eliminating need for indexing. A weld nut is best suited for applications needing high strength.
Some captive fasteners may be installed by pressing the fastener into a pre-drilled or punched hole. In this case, a squeezing force is next applied to embed the fastener in the panel. The squeezing process causes displaced panel material to flow into the shank of the fastener (through a cold flow process) locking the fastener to the panel. The amount of time that force is applied to captive fasteners is important; enough time must be allowed for the material to flow. Because of this, hammers cannot be used to apply force to the captive fastener as the force does not last long enough for the cold flow process to take place.
Captive fasteners are valuable as they add speed during initial assembly and field servicing, thus keeping costs low. Generally captive fasteners use less space and require fewer assembly operations than caged or anchor nuts. Captive fasteners can be used whenever a component must be easily replaced or where hardware cannot be accessible. It is important to keep in mind that the fastener must be compatible with the panel or sheet material being used. In addition, the hardness of the fastener must be greater than the hardness of the panel material.
Industry Applications
- Computers
- Electronic Enclosures
- Exhibits/Signs
- Food Equipment
- Industrial Enclosures
- Medical
- Networking
- Telecommunications
Yuhuang’s captive screws are available in an assortment of styles and sizes to accommodate a wide variety of access and installation requirements. In addition, our Engineers can work with you to create custom captive screws to satisfy your specific application needs.
For more information email us at info@www.yhscrew.com