fasteners
Two
 or more than two parts fastening connection to be a whole USES a kind 
of mechanical parts of the body, on the market, also known as standard.By
 the head and screw two constitute a kind of fasteners, according to use
 can be divided into three categories - machine screw, set screw and 
special purpose screw. The machine is mainly used for screw with 
internal thread hole parts and with a hole between parts fastening, 
 
nut
With
 internal thread hole, the general shape of the flat six Angle type, 
also have a flat square shape or flat cylindrical, with bolt, screw or 
machine screw, used for fastening two parts, make it become a 
Self tapping screw
And
 machine screw similar, but the screw thread for special self tapping 
screw with thread. Used for fastening two thin metal components, make 
into for a whole, member to make holes in advance, because this kind of 
screw has high hardness, can be directly screwing in member's hole, the 
hole component form corresponding internal thread. This kind of 
connection form are detachable connection. 
Wood screw
And machine screw similar, but the screw thread for special wood screw with thread, can be directly screwing in wood component, used to put a bandpass hole metal parts with a solid wood components together. This kind of connection form are detachable connection.