Screws are a common term for fasteners, a daily spoken […]
Screws are a common term for fasteners, a daily spoken word. Non-standard screws are indispensable industrial necessities in daily life: such as very small screws used in cameras, glasses, clocks, electronics, etc.; general screws used in televisions, electrical products, musical instruments, furniture, etc.; as for engineering, construction, and bridges. Large screws and nuts; transportation equipment, airplanes, trams, cars, etc. are used together with large and small screws. Screws have important tasks in industry. As long as there is industry on the earth, the function of screws will always be important.
Screws are mass products, not hand-made artworks. In mass production, the goal is to supply consumers with high-precision, stable quality and popular prices. The accuracy of screws is usually 6g (level 2, American standard "IFI" is 2A thread), and the crude screw used in construction engineering is 8g (level 3, "IFI" is 1A thread).
Screws are mainly classified into three types: ordinary screws, self-tapping screws and expansion screws. Self-tapping screws are screws without nuts. Self-tapping screws are used for non-metal or softer metals, and do not need to drill and tap. Self-tapping screws are pointed, so that they can be "self-tapping"; ordinary screws are flat-headed with the same thickness. The self-tapping screw means: the drilled hole is a chipless tapping hole. The screws used are different from the general ones. The head is pointed and the pitch is relatively large. It is a bit like a chipless tapping. It can be directly screwed without tapping. Go in, metals and plastics usually use this method. It can "tap-drill, squeeze, and press" the consolidated body into corresponding threads on the material to be consolidated by its own threads, so that they can be closely matched with each other.