On the production of the most thermal power engrav

In the early 1990s, affected by the rapid development of domestic packaging market and the rapid renewal of international advanced plate making equipment, plate making equipment and technology developed rapidly, plate making enterprises bloomed everywhere, and the plate market was in short supply. In the middle and late 1990s, with the popularity of computers and the improvement of their performance, the quality of plate making has been greatly improved. The above failure phenomenon caused by alternating stress in metal is high, and the plate making cycle has been continuously shortened. After nearly 20 years of rapid development, China's flexible packaging plate making industry has also experienced a continuous development process

as the saying goes, the quality of printed matter "depends on printing and plate making". So, how about the current plate making technology in China's plastic flexible packaging industry? What is the market situation? What problems should be paid attention to in the process of printing and plate making? In this technical topic, the Department will pay attention to the relevant technologies of plate making with you

the manufacturing process of gravure plate roller, from its development of a series of chain reaction processes caused by overload, there are many process options, including carbon paper photography, direct addition, gravure conversion electronic engraving, digital electronic engraving, corrosion after laser engraving, laser direct engraving, etc. Here, I mainly talk about the production of the most important and widely used electronic engraving gravure roller

from the production process of gravure plate roller, there are mainly the following steps: plate substrate production, plate roller copper plating treatment, original (or design) image document production, plate image electronic engraving production, plate roller chromium plating. Among them, the production of the printing plate substrate and the treatment of the printing plate copper plating roller are carried out synchronously with the production of the original (or design) image file. When the processing of the printing plate copper plating roller and the production of the original (or design) image file are completed, the electronic engraving and production of the printing plate image can be carried out. Finally, the printing plate is chrome plated, so far the whole production process of the printing plate is completed

1. Production of printing plate substrate

the material of printing plate substrate is generally seamless steel pipe, and a few are made of aluminum material. Due to the low price and firmness of steel pipes, most of them use steel pipes, with the weight ranging from 10 kg (narrow width small type printing machine) to hundreds of kg (wide width large type printing machine, monochrome gravure printing machine). The wall thickness of the steel pipe ranges from 10mm to 30mm, and the large-size roller is thicker. According to the needs of printing machines, printing plates are divided into shaftless and shaftless types. Generally, small flexible packaging printing machines use shaftless hollow printing plates, and large printing machines use shaftless printing plates. Before production, the printing factory will first provide the drawing of the plate roller used by its printing machine, and then select the appropriate seamless steel pipe to cut, weld the flange, chamfer and grind the surface of the plate roller in full accordance with the drawing requirements. If it is with shafts, heat the envelope on the shaft of the plate, and then pass the necessary accuracy inspection to meet the technical requirements of the drawing. So far, the substrate processing of the printing plate has been completed. It should be noted here that no matter how good the original plate is made or how accurate the data of electronic engraving is, if a high-precision printing plate substrate cannot be made, the quality of the printed matter cannot be guaranteed. In this regard, gravure is the most stringent among all kinds of printing plates, and various precision processing machinery and equipment used in the manufacturing process effectively ensure the accuracy requirements of the plate roller

2. Copper plating treatment of printing plate roller

whether the substrate of printing plate roller is steel or aluminum material (as long as it can meet the requirements), pre coating should be plated on the surface of the newly processed base roller before making the plate making copper layer. There are many methods to choose from. Such as nickel plating, cyanide copper plating. Then plate making copper layer is plated. This copper layer is the working surface of electronic engraving, so its quality must meet the following requirements: there are six kinds of plastic packaging materials for copper, which can significantly reduce energy consumption and greenhouse gas emissions, with high purity and fine grain; The coating surface shall be smooth without depression, stripe, etc; The coating has enough hardness and toughness. Sulfate copper plating process is a relatively advanced acid high-speed hard copper plating process at present. Its cathode current density can vary in the range of 13 ~ 20a/dm2. The hardness of the prepared copper layer is Vickers (210 ± 10) HV, which can meet the requirements of electroengraving. The anode used for high-speed electroplating consumes quickly. The spherical copper block used as the anode can maximize the actual surface area of the anode to prevent anode passivation. Due to the poor dissolution of pure copper anode, copper powder is easy to produce, which affects the quality of copper layer. However, the copper anode containing 0.1% phosphorus is evenly dissolved and has a high dissolution rate under the same conditions due to the existence of cu3p (non chemical calculation component). General process of sulfate copper plating bath: in this case, the current efficiency of anode and cathode is close to 100%

copper sulfate 150 ~ 300g/L

sulfuric acid 40 ~ 110g/L

temperature 20 ℃ ~ 50 ℃

cathode current density 10 ~ 30a/dm2

appropriate amount of additives

it should be noted that additives are essential for electrolytic copper plating to achieve equivalent speed and quality requirements, and their selection should be specific to the process specification. After the copper layer is plated, it must be cut by a turning and grinding machine imported from Switzerland, or grinded by a grinder, polished by a polishing machine and other processes, so that the diameter tolerance, parallelism tolerance and surface finish of the plate roller meet the requirements. So far, the copper plating plate is basically completed. Due to the process and other reasons, the copper layer sometimes inevitably has sand holes, short scratches and other defects. The remedial methods are as follows: clean the correction area, take the roller as the cathode, lead a wire from the rectifier cathode, wrap the exposed part with cotton, dip the electroplating solution as the anode, and gently rub it back and forth on the area to be corrected until the copper is completely re plated. Pay attention to the adjustment of voltage to prevent the coating from scorching, resulting in the weak adhesion between the brush coating and the plate making copper layer, and the previous efforts are wasted. Finally, polish with sanding paper or grind again

3. The production of original (or design) image files

first of all, we should understand the requirements of customers, whether to copy the original or redesign on the basis of the original, and then scan the original. It is required that the scanned image should be clear, the color should be as close as possible to the original, the text lines should be clear, there should be no phantom, and the size should not be deformed. Then, according to the requirements of customers, we should use professional processing software such as Photoshop Illustrator, freehand, CorelDRAW, etc. produce images, text, gradients, etc. In the process of processing, the following principles should be followed:

first, the overall adjustment of the electrical diagram is the main. Don't choose a lower adjustment here, but choose a lower adjustment there, which is prone to local color deviation. If you can adjust with a curve, try not to use selective correction. 2、 If it can be made with spot color, try to make it with spot color to ensure the stability of printing. 3、 For some plates on small printing machines, due to their slow speed and poor transfer, the electronic division diagram and spray diagram should be slightly deepened as a whole to facilitate the printing of customers. 4、 Small characters should be appropriately thickened, and those with lines smaller than 0.2mm should also be appropriately thickened to ensure that they can be carved. 5、 The method of capping should be engraved with light color into dark color, generally more than 0.2mm, to ensure overprint. 6、 Image color management must be in place, otherwise the final printing plate is difficult to meet the requirements of customers

4. Electronic engraving and production of printing plate image

Shanghai Yuncheng plate making Co., Ltd. uses the advanced engraving machine imported from Germany or Switzerland to rip the image file after the image file is completed, and then operate on the electric engraving workstation. The specific steps are as follows: determine the electric engraving process, make up, install the printing plate, try engraving and engraving. First of all, according to the needs, select the electric carving process used in various colors, namely, line, angle, curve, dark tone, channel, highlight, needle angle, edge enhancement; Then make up according to the jigsaw required by the customer, that is, set the circumference of the roll, the engraving width, the position of the overprint line, the position of various colors and the number of horizontal and vertical patterns, and set the engraving method (spiral, step, seamless connection); Then install the printing plate and prepare for engraving. Before engraving the plate roller, clean and lubricate the surface of the plate roller so that it is not easy to inject and slip the plate during engraving; Then try engraving, select the required electric engraving needle angle according to the set engraving process parameters, and try out the size of the required dot shading, channel and highlight, and then you can carry out formal engraving. After engraving, pay attention to check whether the layout has any abnormal phenomena such as slipping and injection. It is worth noting that the commonly used electric carving needles are 90 °, 3. When a project is given, 100 °, 110 °, 120 °, 130 °, 140 °, the line range of electric carving is from 40 lines to 200 lines, and the angle of electric carving is from 30 ° to 60 °. There are many kinds of matching process parameters. Whether it can be selected correctly is directly related to the product quality of customers, so we must be careful when using it

5. The plate roller is chrome plated

after the gravure plate roller forms a hole on the copper layer through electric engraving, the plate roller production is completed. However, when the ink falls on the non hole part of the copper layer surface during the printing process, the copper surface is easy to be scratched by the scraper, so a layer of 10 should be plated on the copper layer surface μ M hard chromium layer. At this point, a gravure plate cylinder is made. In the process of chromium plating, the following steps are required: cleaning, degreasing, chromium plating and polishing. The purpose of cleaning and degreasing is to remove the grease and dirt from the layout, and polishing is to polish the burr on the edge of the hole during chromium plating. The chromium coating on the surface of the gravure plate roller has high hardness, high wear resistance and chemical stability. It is a necessary procedure to make the printing plate roller without damage to the copper layer on the printing plate surface by chromium plating, and to improve the printing resistance of the printing plate is mainly to improve the hardness of the chromium layer. For example, if the printing number is to reach 800000 revolutions, the hardness of chromium needs to be about 950hv. The hardness of chromium layer is closely related to temperature, current density, chromic anhydride and sulfuric acid content, which needs to be strictly controlled

with the continuous development and innovation of gravure plate making technology, the production process of electronic engraving gravure is also constantly improving, and the fields involved are also constantly expanding. It is believed that in the future, the production process of electronic engraving gravure can still play its unique charm and occupy an invincible position in the gravure industry

reprinted from: Global flexible packaging industry