Analysis and control of dirt on the hottest prints

2022-08-24
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Analysis and control of printing dirt (Part 1)

at present, there are still many unsatisfactory aspects in the quality of offset printing, among which, the dirt on printed matter C. packing list is still lingering, which is one of the common problems of book printing enterprises for many years. Through several years of work practice, the author has found out a set of schemes to control the dirty marks of prints, and achieved good results. Now it is summarized as follows for peer reference

I. Analysis of the source of printing dirt

in order to control the printing dirt of books and periodicals, we must find out the reasons for the formation of the dirt, so as to control the printing dirt purposefully. Through the statistical analysis method of fishbone diagram (as shown in Figure 1), we can see that the dirt of printed products mainly comes from the defects of environment, technology, materials and so on. The specific analysis is as follows:

1 The dirty spots of the film itself

the dirty spots of the film itself mainly come from two situations. One is that the printed film of many textbooks has a long service life. In the process of circulation, such as frequent transfer, storage, copying, printing, etc. between printing plants and publishing houses, the dirty spots on the film gradually increase, while the dirty spots in the graphic part are difficult to remove; The other is that the film is dirty or yellowing due to unclean developer or incomplete development

2. The polyester film base of the film is not clean

3. The environment is not clean, and the floating dust in the working face and air pollutes the film

4. The adhesive tape used for pasting is of poor quality, the edges are degummed, and the adhesive tape marks stick to the dirty film, which is adsorbed to the PS plate during printing and air extraction. When printing, all places with tape marks are dirty

5. The printing glass is not clean or has bubbles

6. PS plate coating or plate base is defective, and the dirt caused by it is generally difficult to remove. 3-position steering valve

7 is selected for hydraulic cylinder The coating on the PS plate was scratched, resulting in dirt

8. The elasticity and density of the developing brush of the PS version developer are not enough, and the development is not complete, resulting in local dirt on the PS version

9. The coating of baking solution is uneven, and the moisture in the plate after baking is uneven, causing local dirt

10. The residual revision paste on the PS version is not removed, and it is easy to get dirty after baking

11. The water roller and ink roller of the printing machine are uneven, and the PS plate is damaged during the printing process, causing the PS plate to be dirty after preliminary surface engineering control and resource estimation

12. Insufficient exposure or development during printing may also cause dirt on the full plate

13. There is crystal scratch on the guide roller of the plate punching machine, which makes the PS plate coating or the guide roller on the plate baking machine dirty

14. The operator's skill or heart is not strong, and the printing plate is not thoroughly cleaned

15. Printing, loading, sample inspection and other production processes may cause dirty marks such as the importance of ink and fingers on environmental awareness

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