In the last episode, we talked about screws, which are known as the "rice of industry". From large-scale aircraft, cars, and airplanes to small items like glasses, mobile phones, tables, chairs, and benches, their manufacturing all rely on screws. Today, let's continue:

The shapes of screws are classified into many types. Generally speaking, the female screws have nuts, while the male screws include screws, small screws, fixed screws, turbine screws, wood screws, etc. Additionally, among the small screws, according to the shape of the head, they are divided into circular, butterfly, flat circular, pot-shaped, flat-shaped, terminal screws, and also include one-line and cross-shaped ones. The commonly referred to bolts are those with a hexagonal head, but there are also square, flat-head, and round-head types. Of course, the nuts are also divided into square, round, etc., just like the screws.