The screw refers to the screw (foreign name: Screw), which is a tool that uses the physical and mathematical principles of the circular rotation of the oblique surface of the object and the frictional force to fasten the parts of the object step by step. A screw is a common term for fasteners, an everyday colloquial language.
Metric threads are measured in MM (millimeters) and have a cusp angle of 60 degrees. Both US and Imperial threads are measured in inches. The cusp angle of the American thread is also 60 degrees, while the cusp angle of the imperial thread is 55 degrees.
