What are security or “one-way removal” screws?

A security or one-way removal screw is designed to be inserted into material, but not removed.

There are several designs of security screw but the most common is characterised by a bow-shaped slot in the centre of the screw’s head.

Material

Security screws are usually made from coated steel.

Application

As the name suggests, these types of screws are used when security is a primary concern.

In a domestic setting, they could be used to protect personal property. On a wider scale, security screws are often used in schools, prisons, hospitals and even on public toilet doors!

There are security screws available for use in a range of materials.

Characteristics

Head shape

Security screws usually have raised heads

Drive type

A security screw can only be inserted using a flat-blade screwdriver bit.

Body shape and tip

Security screws can have either a tapered or straight body, and a variety of different tips.

Threads

Security screws can be fully or partially-threaded. Their threads can be coarse or fine and can be single or twin/double.

How are they inserted?

This type of security screw can be inserted using a flat-blade screwdriver turning in a clockwise direction.

However, two opposing edges of screw’s drive have been smoothed down during manufacture, so if a screwdriver bit is used to try and turn the screw anti-clockwise and remove it, it will slip out of the head.