Analysis of the main factors affecting the quality

Analysis of the main factors affecting the quality of printing products

quality is the life of an enterprise. The quality of products is directly related to the market competitiveness of enterprises. After all, the yield stress of materials is as high as 15 – 45 MPa. In the process of printing production, we must pay attention to ensuring the quality of printed matter and eliminating the quality problems caused by technical errors. This paper analyzes the printing process and discusses the main factors affecting the quality of printing products

I. Influence of plate making film on printing quality

the development and fixing process of film after exposure is directly related to the clarity and contrast of the image on the film turning right into G104 and driving 1.2 kilometers along G104. Therefore, for plate making film, the key is to see the density of the graphic part and the contrast between the graphic part and the non graphic part. The higher the density, the greater the contrast, the better the quality of the plate making film, and the quality of the printing plate made with it can be guaranteed. In addition, the thickness of the plate making film base also has an impact on the plate making quality. Generally, the effect of thin film is better than that of thick film

second, the impact of printing on printing quality

in the process of printing, the intensity of the light source, the distance between the light source and the plate, and the length of exposure time will affect the printing quality. The light source is strong, the distance is short, and the exposure time is relatively short; The light source is weak, the distance is long, and the exposure time is relatively long. Under a certain light source and distance, with the increase of exposure time, the decomposition of the visible film of the plate intensifies until the visible film surface is completely decomposed. If the exposure time continues to increase, the edge of the film surface without light will begin to decompose gradually due to the radiation of strong light, and the lines of the printed plate will become thinner, even broken and blurred. If the exposure time is insufficient, the film surface of the non graphic part is not completely decomposed, and there is still a film on the non graphic part after the development of the printing plate, which will get dirty when printing on the machine. In addition, the exposure time required by different brands of printing plates is also different, which must attract people's attention

in addition, when the printing plate is vacuumed, the degree of film clinging to the printing plate also affects the printing plate quality. If the paste is not true, the printing plate may suffer from ghosting, blurring and other faults

III. Influence of development on printing quality

1. developer concentration

too high developer concentration and too fast development are easy to cause excessive development of the printing plate, thinning of lines, loss of fine points or unclear graphics and text, affecting the printing quality; The developer concentration is too small, and it is difficult to clean the drug film surface that is decomposed by light, and it is easy to dirty the version when printing on the machine

2. Development time

if the development time is too long, the film surface without light on the printing plate is easy to be dissolved, and the pictures and texts of the printing plate will become thinner and thinner, resulting in inaccurate and unclear impressions during printing; The development time is too short, and the film surface decomposed by light is not easy to be completely removed, and it is easy to get dirty during printing. The appropriate development time is that when the printing plate is washed after development, the film surface decomposed by light is just washed away. If the drug concentration is relatively large, the development time should be shortened accordingly; On the contrary, the development time should be extended accordingly

IV. influence of ink transfer on printing quality

the printing process is actually the process of ink transfer. Generally speaking, the total ink transfer rate of offset printing is low, about 38%. The ink transfer rate is about 50% when the printing plate is in contact with the blanket after inking; When the blanket is in contact with the paper, the ink transfer rate is about 76%. It is very important to control the transfer rate of ink. Ink adaptability, ink balance, the performance of printing plate and blanket, paper and printing machine will affect the transmission of ink

1. Influence of ink performance on ink transfer

ink with low viscosity and high fluidity is easier to transfer and has a high transfer rate; The transfer rate of ink with high viscosity and low fluidity is small. To improve the ink transfer rate, we must control the viscosity and fluidity of the ink. The performance of ink will also change slightly with the environment. When the temperature is high, the viscosity of ink is relatively low; When the temperature is low, the viscosity of the ink is relatively high. In actual production, we should choose different types, types and drying methods of inks according to the actual situation. In addition, adding an appropriate amount of inking oil to the ink can adjust the ink performance, which is conducive to increasing the control point and improving the ink transfer rate

2. The influence of blanket performance on ink transmission

blanket must have good ink absorption and ink transmission, and must also have oil resistance, acid resistance, alkali resistance, good elasticity, etc. it officially passed the Boeing certification in 2017. If the blanket is not cleaned thoroughly after printing, the ink remaining in the villi will gradually harden the conjunctiva, causing the villous structure of the rubber surface to be damaged, which will directly affect the ink receiving rate of the blanket and reduce the ink transfer rate of the blanket. Therefore, 10 actuators can be connected at the same time to work synchronously. After printing, the blanket should be thoroughly cleaned. If the downtime is relatively long, a layer of pumice powder can be rubbed on its surface to keep the original fluffy structure on the surface of the blanket all the time, so as to ensure that the blanket has good ink receiving and ink transmission

3. The influence of the adaptability of paper and printing plate on the printing quality

the adaptability of paper is mainly reflected in smoothness, whiteness, stiffness and so on. Paper with high smoothness requires relatively less ink; Paper with poor smoothness requires a relatively large amount of ink. During the printing process, the amount of ink required for different papers varies according to their surface conditions. Under the conditions of the same variety, the same quantity and the same price, the printing quality of paper with high smoothness and whiteness is better than that of paper with low smoothness and whiteness

the quality of the base sand of the printing plate, the hydrophilicity of the metal plate and the lipophilicity of the surface coated with polymer resin film are related to the suitability of the printing plate, affecting the ink transfer and the balance of water and ink on the plate. In the process of plate making, the quality of exposure and development will also affect the performance of the printing plate

4. Influence of ink balance on printing quality

ink balance is a relative balance, not an absolute balance. In the process of high-speed operation of the equipment, the graphic and non graphic parts of the printing plate are both inked and watered, which infiltrates into each other, so ink emulsification is bound to occur on the printing plate. If the amount of water and ink is not well controlled, it is bound to deepen the emulsification of ink, resulting in paste and dirty plates in printing. When printing, we usually use the method of reducing the amount of water and appropriately increasing the amount of ink, but some will also reduce the amount of ink. In addition, ink emulsification will change differently with the change of environment and conditions. In actual production, we should grasp the viscosity of ink and the pH value of fountain solution according to the actual situation, and control the amount of ink and water, subject to the printing plate that is not pasted or dirty

5. Influence of printing pressure on printing quality

printing pressure refers to the interaction between the printing plate cylinder and the rubber cylinder, and between the rubber cylinder and the impression cylinder. It is a necessary condition for ink transmission. The printing pressure is too small, the ink is not easy to transfer, and the ink is light and weak; The printing pressure is too large, and the ink volume expands to the non graphic part, resulting in serious point increase and image distortion. At the same time, it is easy to reduce the printing resistance of the printing plate and blanket. Therefore, the mechanical pressure must be adjusted correctly. Different quantities of paper need different printing pressure. Only the appropriate printing pressure can ensure that the ink color is uniform and the intensity is consistent

v. impact of post press process on product quality

the impact of post press process on product quality is mainly reflected in product specification and size, whether the inner pages are incomplete, and whether the order is reversed. Whether the binding is firm and the appearance is beautiful. Post press processing is also a process that cannot be ignored in the whole printing process

there are many factors that affect the quality of printing products. However, from the perspective of technological process, the above main factors are easy to cause quality problems. Knowing these factors and controlling them can ensure the printing quality, reduce the number of unqualified products, reduce the printing cost and improve the competitiveness