Captive screws

What are captive screws?

In mechanical and plant engineering, captive screws play a crucial role in numerous applications. These special screws feature a unique design that prevents them from loosening or falling out after a component has been dismantled. The use of such screws is particularly essential in situations where the safety and integrity of machine components must be ensured by preventing accidental loss of the screws.

A practical example of the use of captive screws is the fastening of sheet metal cladding to machines. Here, a captive screw ensures that it remains connected to the panel even after it has been removed. This feature of the screws not only contributes to convenience, but in many cases also meets legal requirements.

Captive screws are important for compliance with the Machinery Directive

This is not only convenient, but in many cases mandatory. The Machinery Directive 2006/42/EC requires this property for protective devices in order to enable CE marking: “The fastening devices must remain connected to the protective device or to the machine after the protective devices have been removed.”

How this requirement is to be implemented is not prescribed. There are various constructive options for this. One of these are so-called E-washers, which are attached to the shaft of the screw after it has been inserted through the hole.

Another option is special screw-washer combinations with washers that taper their diameter after the initial tightening.

Why are captive screws so expensive?

Captive screws are only offered by relatively few manufacturers and are manufactured in smaller quantities than conventional screws. This increases the costs of production and logistics. In addition, the screw and washer must be matched to one another in order to ensure the clamping effect and thus meet the Machinery Directive. However, common systems are very easy to install and thus save valuable working time.

A cheap alternative source for captive screws

For companies that require larger quantities of captive screws, there is the option of having them manufactured cost-effectively by contract manufacturers. We have extensive contacts with such manufacturers and can offer you a cost-effective alternative to purchasing these screws. If you are interested in larger quantities of captive screws for your company, please feel free to contact us Email Contact us.

Last revised on August 30, 2023 by Andreas Janisch