Most popular relief printing ink color control 0

2022-07-31
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Relief printing ink color control

in the relief printing process, the following factors are closely related to the quality of printing ink. It is of great significance to correctly understand the relationship between these factors and ink color for accurately controlling the ink quality of printed matter

correctly adjust the printing pressure

1 Check the technology of printing plate bottom pad: the wooden structure bottom pad is the traditional bottom pad material of embossing process, but its stability is poor, and the ink color changes greatly during the printing process. If it is used to print large format plate products, the ink color is easy to be blurred and shallow, so it is only suitable for printing small format plate products. When printing large format plates including field products, the magnetic plate holder (bottom pad) of cast iron structure or the plate holder of other metal structures should be used

2. Check the technology of plate cylinder lining: the lining material shall be made of materials with small compression deformation coefficient and good elasticity, so as to avoid affecting the uniform and full transfer of ink due to the settlement of the lining body after stamping. Generally, when the surface of the substrate is smooth, the printing building materials industry should be more aware that the development of new materials will cut off the strengths of the building materials industry, adjust the structure, increase the effective supply, accelerate the transformation and development of the text version and the line version, and should choose neutral and hard lining; When printing the paper with rough surface, it is better to use a soft and elastic lining to prevent the ink from getting scratchy and shallower due to the poor contact between the rough paper surface and the layout. In addition, during the printing process, attention should be paid to whether the pressure stability of the lining is affected due to excessive stamping times and the presence of depression. At this time, timely measures should be taken to patch or replace the lining to ensure that the ink color is uniform. However, for overprint products with high precision, the lining must not be replaced during the printing process, and the lining thickness must not be increased blindly to eliminate the phenomenon of imprinting

correct adjustment of ink roller device

1 Reasonable selection of ink roller: the rubber ink roller has a hard texture, strong toughness, and is not prone to plastic deformation. It is more suitable to act as an ink transfer roller and an ink leveling roller for printing lines and text plates. If it is used for printing real map plates, it is prone to printing bar marks and uneven ink distribution. The plastic ink roller has the advantages of soft texture and good elasticity. It can not only be used as the ink roller printing plate product, but also be used to print the line or text version of movable type plate

2. Adjust the contact position between the rubber roller and the inking iron roller: the relief platform printing machine with circular flattening structure is generally equipped with several groups of inking devices. If the rubber roller and the inking iron roller are in poor contact, it is bound to cause insufficient and uneven ink transfer, resulting in uneven ink depth on the horizontal layout of the printed matter. For this, the bearings at both ends of the rubber roller shall be adjusted to make the rubber roller and the iron roller contact evenly. After adjustment, a 0.05mm steel sheet can be inserted between the rubber roll and the iron roll for inspection, and it is better to have obvious resistance when pulling the steel sheet

3. Adjust the contact position between the inking roller and the layout: if the inking roller is adjusted too high, the layout will not get a uniform and sufficient amount of ink, and it is easy to produce print marks due to the slipping of the inking roller in the layout. If the inking roller is adjusted too low, the ink on the plate will be scraped to the trailing tip of the printing plate, resulting in a shallow front and a deep back ink color. The inking roller and the plate shall be adjusted to be in parallel and uniform contact. A 0.05mm steel sheet can be inserted between the inking roller and the plate to avoid obvious resistance during drawing. If the machine is equipped with a height gauge accessory, you can use it to insert it into the plate table and pull it, taking the resistance of the inking roller to the plate as the degree

reasonable selection of plate materials

zinc plate is not suitable for printing plate products with large format market cooperation and improved by modified plastics. Resin plate is an ideal plate for printing plate products, especially for printing large format products. Using offset paper with poor gloss for printing plate products and resin plate for plate making and printing can better prevent ink color from blooming and lightening

correctly adjust the ink feeding device

1 Frequently stir the ink in the ink bucket and pay attention to adding ink at appropriate times: during the printing process, the ink in the ink bucket should be frequently stirred with an ink knife to prevent sedimentation and suspension. In addition, due to the reduction of the ink amount in the ink bucket, the gap between the ink bucket steel plate and the ink transfer iron roller is easy to become smaller, resulting in the reduction of the ink output and the shallower ink color of the printed matter. In order to avoid this situation, we should also pay attention to regular inking in production

2. Scientifically and reasonably adjust the inking device

(1) adjustment of local ink color depth at the horizontal part of the printed matter: if a section of the horizontal layout is dominated by words, lines and lines, its ink absorption is relatively small, the corresponding ink bucket steel plate adjusting screw can be screwed in to appropriately reduce the ink delivery at this part. If the position of a section of the horizontal layout is dominated by the field and plate, the ink feeding amount shall be increased accordingly to keep the ink color of the whole page uniform

(2) adjustment of full page ink color depth: different inks in the ink bucket need to increase or reduce the conveying capacity comprehensively. There are two adjustment methods: one is to adjust the gap between the ink bucket steel plate and the ink transfer (ink feeding) iron roller; Second, it is realized by adjusting the rotation radian of the ink transfer iron roller. When the ink is thin, the gap between the steel sheet and the iron roller should not be adjusted too large to avoid ink leakage and uneven ink color. When adjusting the ink feeding amount, the price of these machines also varies greatly. The rotation arc of the ink transfer iron roller should be controlled within 1/2 of its adjustment range, so that the ink feeding amount can be flexibly adjusted when the ink thickness changes during the printing process

correct adjustment and use of ink

generally speaking, when the temperature is low, the ink appears thick, and its fluidity is poor, which is easy to cause poor and uneven transmission. For this, according to the characteristics of the printed matter, select additives to dilute the ink appropriately, so as to maintain good fluidity and transmission effect, so as to keep the ink color uniform. If the ink is too thin, the ink color of the printed matter will appear very light. For the adjustment of ink fluidity, full consideration should be given to the characteristics of the printing machine speed and ink transmission structure. If the speed is fast, the ink path is long, and there are many ink rollers, the ink is easy to become thinner and shallower due to the large friction coefficient. Therefore, the above situation should be fully considered when allocating ink, and the printability of ink should be reasonably adjusted. In addition, when blending intermediate and multi-color inks, try to avoid mixing inks with different specific gravity, so as to avoid "layering" (sedimentation and suspension) of inks on the ink bucket due to different specific gravity during printing, resulting in printing color difference

control the operation technology

first, pay attention to the reasonable maintenance of the machine, and maintain the Feida and air pump at ordinary times, so as to keep the mechanical parts in good use condition, and make the air path unobstructed and the printing suction smooth; Second, according to the thickness and size of the printing sheet, adjust the Feida, air pump and the parts related to paper feeding to ensure the normal transmission of the printing sheet; Third, necessary adjustments should be made to the printability of the paper. For example, through the process of paper bumping and seizing, the paper conveying can eliminate the phenomenon of adsorption and adhesion, and maintain a certain stiffness, so as to facilitate the smooth paper conveying, and at the same time, it can better avoid the occurrence of empty sheets, multiple sheets and paper feeding skew; Fourth, the paper stacking operation technology should be well controlled. If the paper stack is not flat, measures should be taken in time to flatten it so that there is no obvious height difference on the paper surface. Through these measures, the paper feeding is kept continuous to prevent printing color difference caused by parking

reprinted from: printed in Shenzhen

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