What is a captive screw?

A captive screw is a special type of fastener that is designed to stay fixed to the component it is securing, preventing it from falling out completely. This feature makes it particularly useful in applications where a lost screw could be a problem.

The design of a captive screw typically includes a standard threaded portion as well as a reduced diameter along part of its length. This allows the screw to be inserted into a panel or assembly until the reduced diameter can move freely. To hold the screw in place, it is often paired with a retaining washer or flange whose internal threads match the screw. After the screw is inserted, the washer or flange is tightened, ensuring that the screw remains securely connected and cannot be completely removed.

captive screws are used in a wide variety of industries including electronics, food processing, control panels and special machinery. They serve a safety function, especially in environments where contamination must be avoided, as they help to secure the fastener within the panel.

Learn more about traditional screws in our guide,Machine Screws: What Do You Know About Them?

Differences between captive screws and standard screws

captive screws operate differently than traditional screws, primarily because of their unique design and function. Here are the key differences:

1. Prevents falling out: captive screws are designed to avoid completely falling out of the component they are securing. They incorporate features such as retaining washers, specialized threads, or other retaining mechanisms to keep them in place even if they become loose. In contrast, standard screws can be completely disassembled, which increases the risk of loss.

2. Easy to operate: The captive screws make operation simpler during assembly and maintenance. Its design minimizes the possibility of screw loss, making it more convenient to open and close access panels or doors without worrying about misplacing fasteners.

3. Enhanced Security: captive screws are engineered to remain partially secured even if they become loose. This is especially important in environments such as food manufacturing, where a lost screw can cause production to stop until the screw is found. Unlike traditional screws that can be easily misplaced, captive screws help maintain operational efficiency.