The main materials of the rotary encoder: metal, glass, and plastic. The glass code disc is a thin engraved line deposited on the glass. Its main features are good thermal stability and high precision. The metal code disc is directly engraved with and without , Not easy to break, but because the metal has a certain thickness, the accuracy is limited. Its thermal stability is an order of magnitude worse than that of glass. The plastic code disc is economical, its cost is low, but its thermal stability , Accuracy and life expectancy are worse.