How to reduce the scrap rate in CTP plate making
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1. Keep the PS version clean and flat
The Topsetter 102 is an external drum type plate-making machine, which requires a particularly high degree of cleanliness and flatness of the plate, especially when it comes to the work of the FM network. In the early stage of CTP use, when the work of the FM network is out, the level jump phenomenon often appears on the flat net (a small deeper area is seen by the naked eye, and the dot is obviously denser than the surrounding area under the magnifying glass) . After excluding the reasons of the file itself, after repeated experimental analysis, it was finally found that the floating dust or unevenness on the plate caused uneven heat absorption during exposure and uneven heat crosslinking reaction.
For the above reasons, we require the operator to wear a clean work glove when loading the CTP plate. The plate is vertically drawn from the plate and placed directly at the entrance of the Topsetter 102, and the folding must be prevented during the delivery process. (Our company uses the Graphics0770×1030 plate from Kodak Polychrome, which is only 0.3mm thick and is extremely easy to fold).
2. Adding and deleting content on the plate
Although the customer has signed the proof of digital proofing before using the CTP system to output the printing plate, and the quality inspectors have also carried out strict proofreading, there are still inevitable problems in the content of individual printed products after the printing plate is finished. For example, sometimes the version lacks one or two solid content (such as lines, punctuation marks, etc.) with 100% dot percentage. If there is no color fit, the plate does not need to be re-out, and can be compensated by the following methods: First wipe off the protective glue on the plate, use the stylus to score on the plate (the force should be moderate), then put the ink on, and then wipe the protective glue (but the print volume of this version can not exceed 3000).
If there is any extra content on the plate, if it does not involve color fitting, you can use the Starlight PS plate to repair the solution, and wipe it with water, then wipe the peach.
3. The processing of the floating plate on the printing plate during the publishing process
The plate used in Topsetter102 is a heat-sensitive CTP plate. When the temperature exceeds a critical value during exposure, the image portion is cross-linked to form a latent image. When developing, this portion is insoluble in the developer, while the unexposed blank portion of the resin The layer was dissolved in the developer because no crosslinking reaction occurred. After a certain period of time and a certain amount of the plate material is developed, a part of the resin layer in the developing solution forms a lot of flocs, which are attached to the finished plate, and if not treated, it may cause dirt during printing. The solution is: 1 frequently clean and replace the filter core of the developing machine; 2 thoroughly clean the developing machine before starting the printing plate, especially the rollers in the developing machine; 3 for the floating dirt on the printing plate, available Wipe off the protective glue first, use a small brush to lick a little developer solution and gently trace it in the floating area, and quickly wipe it with water. Repeatedly, it can be removed (note that the residence time on the plate must be short, otherwise it will Injury the small dots around), then rub the protective glue.
4. Insufficient processing of printing plate development
When the developer (Kodak Premium CTPPositive Developer) is fatigued, for the Kodak Polychrome Graphics 0770×1030 plate, the layout of the blank portion will be blue and the machine will be dirty. For this kind of plate material, secondary development can be carried out to meet the printing quality requirements (but attention should be paid to the development conditions. Usually, we will adjust the development time and brush speed to twice the original, and must detect the change of the printing plate on the Internet. ).
In order to maximize the use of the developer and ensure the quality of the printed plate, depending on the degree of fatigue of the developer, we can make up for the following two methods: 1 adjust the plate calibration curve value; 2 increase the development time or development temperature or Increase the brush speed.
All of the above methods can effectively reduce the scrap rate in CTP plate making, thereby reducing the cost of CTP plate making.