There are many types of offset printing machines, including single sheet fed screen printing machines and roll fed rotary offset printing machines; There are monochrome, two-color, four-color and other offset printing machines available; There are full sheet printing machines, split printing machines, four open printing machines, etc. Flat offset printing machines are mainly used for paper printing and are now being increasingly used in flexible plastic packaging printing. It has a faster plate making speed than gravure printing, is cheaper in price, and is suitable for small batch fast offset printing machines. It consists of a paper feeding system, a water and ink conveying system, an embossing system, a paper receiving system, and a transmission mechanism. The majority of domestic high-speed production machines are used for single sheet feeding offset printing, with a speed of 5000-10000 sheets per hour. They can be used for roll paper rotary offset printing of plastic source films, with a speed generally ranging from 15000 to 3000 pm/hour. There are single color, double-sided dual color, double-sided tri color, etc. The plate materials used for offset printing include protein plate, flat four plate, multi-layer metal plate, pre sensitive plate, and zinc oxide paper-based plate. The copied process flow is as follows
(1) Photography, color separation, and screening. Use a plate making camera with a color filter to capture the original manuscript (black and white or color) in yellow, cyan, and red. Electronic color separation methods can also be used to separate the original manuscript into color films,. A negative image produced by photographic or electronic color separation, which can be used for uniforms by adding a screen and taking a negative plate with network lines that can express layers, is a process of copying a color separated photographic film with dots onto a metal printing plate for printing, regardless of the type of printing plate.
(2) Plate printing
The process operation of plate printing can be divided into surface treatment, which light, plate chemical treatment and other steps to complete.
