What Will Influence the Printing Quality of PS Plate
The PS plate for offset printing should be of high quality, especially for the high-end color printing, which does not allow any defects. To ensure the quality of PS plate, we must pay attention to the surface quality of aluminum base plate.
Generally speaking, the aluminum sheet manufacturing process is ingot milling- hot rough rolling- secondary hot rolling- cold rolling-drawing/bending/straightening-longitudinal cutting. During the rolling process of aluminum plate, a very thin oxide film is naturally formed on its surface. The thickness is generally 0.01 to 0.05 mm.
In addition, rolling oil and other dirt (such as dust) may remain during the processing of the aluminum sheet. These extremely thin oxide films and dirt will directly affect the electrolytic grains of the aluminum base plate,which lead to poor printing quality or low printing resistance of the PS plate.
The surface of the aluminum base plate should be clean, flat, no cracks, no corrosion, no severe scratches, no peeling, no oil marks,etc. And the slight color differences and bright stripes are not allowed. This is the basic requirements of PS plate on the aluminum sheet.
The unevenness requirements of the aluminum base plate for the PS plate:
The gap between the unrolled coil and the plane should not be greater than 1mm. No more than 3 waves per meter.
The length of bent side per meter is not more than 1 mm.
The coil should be rolled tightly. The ends should be neat. No cracks or burrs are allowed.
The PS plate making process has has stricter requirements on the aluminum base plate. For example, the thickness of aluminum base plate should be 0.275 mm, which is not allowed to too thin or thick.
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Tags: ps plate making process aluminum base plate ps plate for offset printing