Captive Panel Screws – An Overview

What is a captive panel screw?

A captive screw describes, in general, a screw which remains attached to a panel even when its threads are not engaged. This is usually accomplished with the use of a retaining washer or similar method which prevents the disengaged screw from falling back out through its installation hole. The overriding benefit of captive panel screws in the field is the prevention of lost fasteners on access panels and doors, especially in those applications where safety and security are major considerations. Most captive panel screws share the following characteristics: machine screw threads, a head, and an unthreaded shank, between the head and the threads, with a diameter at or below the minor diameter of the threads. There are no current consensus standards for this category.
Determining the exact dimensions and the type of captive screw required is the result of a number of different considerations, mostly dictated by the application. Many designs include characteristics such as knurled sides, shouldered bearing surfaces, slotted heads, wide heads, narrow heads and pointed ends. The most critical elements involve:

1. Properly matching the threads between the panel screw, the panel hole, and its receptacle

2.Properly matching the overall screw length and its captivated length with the gap between the panel and the receptacle

3.Properly matching the retainer to the screw and panel hole

When these three elements have been correctly addressed in the captive panel assembly, everything else becomes a matter of design preference.

How is a captive panel screw manufactured?

Often, engineers will choose a captive screw for an application by matching the need to an existing screw, such as those found in the Products Section of the Richard Manno & Company website. Other times, special dimensional requirements may dictate that prints needs to be drawn. In either case, the captive screw is manufactured from bar stock in a variety of different materials, such as 303 S/S, 416 S/S, Brass, and Low-carbon steel, as well as others.


The diameter of the head usually determines which type of screw machine runs the parts. Swiss screw machines are great up to 1” in diameter, while the larger diameters are run on Brown and Sharp equipment. Blanks are produced by the screw machines and then moved into secondary operations for milling, knurling and thread-rolling. Washing of the parts, followed by the application of the prescribed finish, completes the job.

For captive screws that use standard machine screw or socket cap dimensions, the option exists to centerless grind a portion of the threads. There are inherent issues in this method which may render a captive panel screw assembly inoperable. One issue results from the pressure on the remaining threads during the grinding process. Not only does the first remaining thread close from the pressure, the next few threads may exhibit contact damage from the grinding process. Chasing the collapsed thread open or chamfering it out of existence does not repair the damage to neighboring threads. In order to ensure that full form threads are available to fully engage in the assembly, the threads should always be re-rolled after grinding. At Richard Manno & Company, we believe in doing things the correct way, whether we’re manufacturing from the bar or modifying from existing products.