@lunwencheng620
Активность: 3 года, 7 месяцев назад
A screw and a bolt are similar types of fastener typically made of metal and characterized by a helical ridge, called a male thread (external thread). Screws and bolts are used to fasten materials by the engagement of the screw thread with a similar female thread (internal thread) in a matching part. Screws are often self-threading (also known […] Просмотр