How to reduce ghost failures during printing
The problem of "ghosting" is often encountered in the printing process. At this time, the film and printing plate have been prepared, and the revision is not realistic. The only way to take is to try to minimize ghosting during the printing stage. In the following, we will introduce how to reduce the ghost fault to the lightest with Mitsubishi 3F offset press.
1. cause
We want to print a picture. Since there are vertical ink sticks between the two horizontal ink sticks, a larger amount of ink is required in the circumferential direction corresponding to the vertical ink sticks. However, in high-speed printing, if sufficient ink can not be replenished on the inking roller in time, or the amount of ink in the horizontal bar corresponding to the vertical bar is less than that in other parts, it is easy to produce ink shortage ghost.
2. Troubleshooting
Although the following methods cannot completely remove ghosts, they can reduce them to almost invisible levels.
(1) Adjust the ink supply system. Since the layout with vertical bars requires a larger amount of ink, we can increase the ink volume of the ink keys corresponding to the vertical bars to supplement as much ink supply as possible. However, due to the axial tandem movement of the ink inking rollers, in order to ensure the uniform ink color of the entire horizontal bar, the amount of ink should be reduced on both sides of the corresponding part of the vertical bar. This ink volume plus the ink volume transferred in series can basically ensure the uniformity of the ink volume of the horizontal stripe.
(2) Control the dampening method. There are 3 types of dampening methods for Mitsubishi 3F offset printing machine. Three modes can be switched at any time on the remote control station. When ghosts appear, another form of dampening is generally used. In this dampening method, since the transfer roller 2 is separated from the inking roller 5 and the ink leveling roller 6, the ink remaining on the inking roller 1 cannot be transferred, so these extra inks can be used as a supplement to the ink shortage on the plate To reduce ghosting. The water fountain roller of this dampening method has the lowest rotation speed, and the ink emulsification degree is small.
(3) Adjust the water supply. We know that in the printing process, the water-ink balance is a relative balance, and the content of the fountain solution in the ink can be achieved between 15% and 26%. When the fountain solution is controlled to a balance of more ink and less water, the ink emulsification value is the smallest. Relatively speaking, in the same amount of transferred ink, the degree of emulsification is small, and the ink content in the printed product is high, so the printed ink color is saturated and bright , Can reduce the ghost effect to a certain extent.
Through the combined effect of the above three methods, the effect of ghosting faults during the printing process can basically be reduced to a small amount, thereby improving the quality of the printed matter. This method is very effective in actual operation, and can directly print high-quality products without changing the design and process of the printed products.
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