Non-standard is lower than the national standard. Special screws are special equipment or specially customized.
Screws in Special Screws A type of fastener consisting of two parts of the head and the screw with an externally threaded cylinder needs to cooperate with the nut to fasten two parts with through holes. This type of connection is called a bolted connection. If the nut is unscrewed from the bolt to separate the two parts, the bolt connection is a detachable connection.
The set screws for special screws are mainly used to fix the relative position between two parts. Special-purpose screws such as eyebolts are used for lifting parts. The screw is also a type of fastener consisting of a head and a screw. It can be divided into three types of machine screws, set screws, and special-purpose screws depending on the application.