Using PS Plates for Proofing and Printing on a Coin Printer

PS version has the advantages of high resolution, good printability, and plate making and printing process. It is widely used in the printing industry.
From the point of view of the conventional process, the PS version is only used for offset printing machines. Is it possible to break the traditional concepts and processes and use the PS version on the Toppan automatic platform printer? With this rather significant question, the author boldly conducted some explorations and experiments and achieved satisfactory results. The specific approach is described below.

First, the correct adjustment and use of ink roller

Since the layout of the PS plate is in a horizontal state, that is, the ink receptive layer and the hydrophilic layer of the plate are almost on the same surface, it is required that the hardness of the ink roller used should be appropriate. If the surface of the roller body is too hard, it will be easy to cause wear on the plate surface, and it is difficult to achieve uniform ink transfer and water transfer. The colloidal surface of the ink roller should also be kept intact to ensure that the ink and water on the ink roller can be coated more uniformly. In addition, at least three ink sticks should be used to ensure that the printing ink layer achieves better results.

Second, roller lining process requirements and technical specifications

In the use of PS plates in letterpress printing machines, the printing method differs from the use of offset printing equipment in that indirect printing is directly printed. That is, the printed sheet is pressed by the lining body on the impression cylinder so that the printed sheet is directly contacted with the surface of the printing plate to obtain the imprint. This process requires that the lining should have good flatness and elasticity. Therefore, when printing, the lining material should use offset blanket or fabric cloth. At the same time, it is required that the lining of the bag be evenly and tightly attached to the surface of the drum, and that the lingering of the lining should not occur and the phenomenon of loosening or bulging should occur, so as to avoid the increase of the wear of the plate due to the bad contact between the printed sheet and the stencil, which affects the printing quality and the printing plate. Printing rate.

Third, the plate process technology and its operating requirements

From the point of view of the quality and effect of the printing process, the use of the PS plate in the circular flattening structure printing press has a crucial effect on the printing effect and quality. If the flatness of the platen is not good, it will inevitably lead to uneven pressure. Even if the partial plateau pressure is heavy, it is easy to cause damage to the plate mask layer. Therefore, the printing plate should be made of magnetic plates or aluminum plates. In this way, the double-sided adhesive tape can be used to directly bond the back of the PS plate and the plate surface. If the layout area is small, you can also refer to the embossing process, and use a PS plate with sporadic interception to print. This can not only save the plate material but also avoid the possibility of dirtiness due to the large surface area of ​​the water film layer. . In addition, since the PS plate is much thinner than the thickness of the relief plate, intercepting a small area of ​​the PS plate directly pasting on the surface of the platen will inevitably cause ink on other parts of the platen surface to fail to realize normal printing. For this reason, it is necessary to achieve printing by adding a certain thickness of plate base to the PS plate. Here is an example to illustrate. For example, the printed graphic area of ​​a type of print is 5 x 1Ocm, so only a PS plate of 6 x 11cm format can be produced. At the time of loading, this plate can be bonded to a piece of white paper with a thickness of 0.5 cm and an area of ​​5.5 x 10.5 cm with double-sided tape, and then the plate is pasted together with white paper (adhesive tape on the back). Version can be above.

Fourth, put a good print pressure debugging

Because the PS plate is used on the letterpress printing press, the printing plate and the printed sheet are directly contacted with each other for printing. Once the pressure is uneven or there are heavy weight conditions, the PS plate mask layer is bound to be easily worn by the paper, which affects the printing quality. , Decrease the printing rate of the printing plate. Therefore, the printing pressure must be adjusted to the lightest limit, while ensuring the uniform transfer of the ink layer on the layout. The debugging pressure must grasp a principle that, under the condition of meeting the ink supply of the layout, the pressure should be gradually increased from blue to heavy, so as to avoid blindly aggravating the printing pressure due to insufficient ink supply.

V. Adding water delivery devices

When using the PS plate for proofing printing on the embossing equipment, a damp cloth can be used to wet the plate with the dampening solution, and the ink can be proofed after printing. If it is mass-produced, a water supply device should be added. If the ink is used for printing, a water delivery device can be installed on the upper part of the machine chain ink roller. This way, the water channel can be evenly distributed to the layout through the string roller, and a more uniform dampening effect can be achieved. In addition, depending on the structural characteristics of the machine, a water delivery device can be installed in a certain area.