E-Ring makes the fastener captive on this battery compartment screw captive screw on a Selfie stick E-Ring on the bold of a camera belt A captive fasteners is an engineered

fastener A fastener (US English) or fastening (UK English) is a hardware device that mechanically joins or affixes two or more objects together. In general, fasteners are used to create non-permanent joints; that is, joints that can be removed or disman ...

designed for a permanent hold 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. A captive fastener is sometimes made with thread locking,

press-fitting An interference fit, also known as a pressed fit or friction fit is a form of fastening between two ''tight'' fitting mating parts that produces a joint which is held together by friction after the parts are pushed together. Depending on the am ...

, or

broaching The BROACH warhead is a Tandem-charge, multi-stage warhead developed by Team BROACH; BAE Systems Global Combat Systems Munitions, Thales Missile Electronics and QinetiQ. BROACH stands for ''Bomb Royal Ordnance Augmented CHarge''. Development of ...

to accomplish an anchor-hold within a larger assembly housing. However, a captive fastener may also be melded with the material into which it is joined, either through

cold forming In metallurgy, cold forming or cold working is any metalworking process in which metal is shaped below its recrystallization temperature, usually at the ambient temperature. Such processes are contrasted with hot working techniques like hot roll ...

welding Welding is a fabrication (metal), fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing Fusion welding, fusion. Welding is distinct from lower ...

. Captive screws are a type of

machine screw A screw and a bolt (see '' Differentiation between bolt and screw'' below) are similar types of fastener typically made of metal and characterized by a helical ridge, called a ''male thread'' (external thread). Screws and bolts are used to f ...

which are frequently used for safety reasons, often with a captive washer. They are now required by EU law on equipment such as safety guards so that machinery complies with EU Machine Safety Directive 2006/42/EC.

References

External links

Accurate Screw Machine
{{tool-stub Fasteners