The copper screw is the largest invention of human beings according to the application field.
The copper screw is also a type of screw. There are many kinds of screws, whether it is a tiny screw for glasses or a large screw for heavy-duty heavy-electricity engineering. The main purpose is to use a high degree of industrial products to form a fixed one, if the use of teeth and teeth often occur Inadequate closeness, too tightly locking the screw head off, or bad teeth lock failure to meet the conditions of use, are all quality accuracy issues. Screws are "quantity products" and are not hand-made artworks. In mass production, they are intended to provide consumers with high-precision, stable quality and popular prices. The accuracy of the screws is usually 6g (2nd grade, U.S. specification "IFI" is 2A teeth), and the crude screw used in construction projects is 8g (3rd grade, "IFI" is 1A teeth). The value of screws is very important. There are examples in the world of bankruptcies caused by poor screw quality. There are also examples of aircraft crashes and vehicle subversion due to poor screws.
The value of copper screws and their importance, a good quality screw, can not fall for a hundred years. A poor quality screw may be related to life.