Metal tin printing belongs to offset printing, but metal printing has different characteristics from general offset printing.
① The substrates for metal tin printing are various metal sheets. At present, the substrates used in metal printing are commonly used tin-plated steel sheets (also known as tinplate), chrome-plated steel sheets, ordinary steel sheets, and aluminum alloy sheets.
According to the different hardness of these metal sheets, the adjustment of the roller pressure is the key to the operation. In addition to printing, it can be divided into three types: hard iron, neutral iron and soft iron. Aluminum alloy sheet is soft, ordinary sheet steel is neutral, and chrome-plated sheet is hard. In the printing process, depending on the hardness of the substrate, adjust the roller pressure and select the appropriate lining material.
②Coating plays an important role in the quality of metal tin printing. The coating can increase the adhesion between the sheet and the ink layer, and protect the ink film layer on printed tin.
③ Metal printing use special printing ink. Since the surface of the substrate printed on tinplate is smooth and has no absorption capacity, the metal tin printing ink is dried by oxidation conjunctiva and volatilization.
At the same time, printed tin is generally used in cans after printing, and the printing inks are required to be resistant to high temperature, retort, and once non-toxic.
④The metal tin printing operation is different from general offset printing. When the printing press is manufactured, the blowing force of the blowing nozzle and the suction force of the mouthpiece should be considered, and a horseshoe-shaped magnet should be added at the feeding place to overcome the adsorption force between the iron sheets.
During the operation, the air volume of the blowing nozzle and the suction nozzle should be adjusted according to the substrates of different weights.