1. Common flexographic printing plate material parameters
2. How to design a flexographic ink map that is convenient for overprinting
In the printing process, a key indicator that people often pay attention to is overprinting, because waste products caused by inaccurate overprinting often account for a large proportion of all waste products. Although the flexographic printing machine manufacturers have provided a good basis for accurate overprinting in the design and processing process, and the automatic monitoring system has also provided a guarantee for accurate overprinting, but the operator's technical level and proficiency also have a great impact on the accuracy of overprinting . If you can make some adjustments for the convenience of overprinting when designing ink drawings, you can greatly reduce the difficulty of printing and reduce the rate of waste. The easiest way is to use reverse white characters when designing the original ink manuscript, or hollow out between the two colors to form a reverse white outline, or you can cover the third slightly thicker at the edges of the two colors overprint Dark contour lines, for the printing of finer prints, trapping technology can be used, the amount of trapping depends on the accuracy of the printing press, the quality of the paper used for printing and the level of the operator. Trap processing is easy to implement on a computer. If there is no computer, only ready-made dichroic film, you can use a special trapping processor (TrappingModifier), enter the amount of trapping amount, the machine will automatically generate a trapped processing Film. If there is no trapping processor, you can put a transparent spacer between the color separation film and the copy film, and expose it with a single point light source copy machine, and you can also get a film with a similar effect. What are the requirements for the type of film for making flexo
When placing the flexographic plate on the front of the plate-making machine, in order to ensure the quality of the film and the flexographic printing surface, the plate-making machine is equipped with a vacuum pump to evacuate, and the side of the film close to the flexo must be rough (matte), This can prevent air bubbles remaining between the flexible film and the flexo plate and affect the quality of the flexographic printing surface. The pressure bar used to press the edges of the flexible film and the flexo plate should also adopt a kind of indentation that can conduct air laterally. In addition, there are specific requirements for the blackness and transparency of the film.
3. How to make high-quality online version and field version on one printing plate at the same time
Generally speaking, when the printing unit of the flexo printing machine is sufficient, the screen version and the solid version of the same color should be divided into two productions, because the screen version requires a thinner layer of ink, while the field and line version need to be thicker Ink layer. However, in some special cases, it is necessary to print the same color of the network cable and the solid image on the same plate. In this case, on the one hand, when printing, the selection of the anilox roller has to be compromised. Usually, the printing requirements of the stencil are first met, at the expense of the thickness of the solid ink layer. On the other hand, when making a plate, Master different exposure times to ensure the quality of the Internet and field parts of the same printing plate. The difference between the screen image part and the field part is mainly the depth of corrosion. If the screen part is to "stand" during the process of scrubbing the printing plate, it needs to have a strong foundation, so the corrosion depth is shallower. Different etching depths can be obtained with different back exposure time by covering the local method. The front exposure time should also be done in a similar way, but it is said that the current flexographic plate manufacturer has introduced a new type of flexographic plate. Regardless of whether the printed part is a screen or a field, this plate requires only a uniform front exposure Time, avoiding the trouble of multiple exposures, making flexo plate making more convenient.
Fourth, what should be paid attention to when using the squeegee
Whether to use the doctor blade in the ink transfer system is optional. For rough field printing or UV coating, there is no need to use the doctor blade, just adjust the pressure between the rubber ink roller and the anilox roller. You can get a substantially uniform ink layer. For the printing of general printing products, the doctor blade should be used. At this time, the pressure between the rubber roller and the anilox roller should be smaller, to ensure that enough ink hits the blade edge uniformly, so that behind the doctor blade In order to get a uniform ink layer. In addition, the screws on the doctor blade holder should be carefully adjusted. The screws can change the contact pressure between the doctor blade and the surface of the anilox roller. If the above method does not work, that is, a smooth and uniform ink layer is still not available, you can check the blade of the doctor blade to see if it is physically damaged or unhealthy. It may also be that the screw fixing the doctor blade holder is loose, causing the blade and the net The axis of the pattern roller is not parallel. Don't scrap scrapers with small defects easily, you can run them in other spare printing units, and use them after the defects are removed. An squeegee can continue to be used even if it wears off a few millimeters in its lifetime.
5. Why use water and ink to monitor pH and viscosity at the same time
Everyone knows that changes in the viscosity of printing ink have a direct impact on the inking volume of the printing plate, so if the viscosity of the ink changes, it will also affect the printing quality. Therefore, it is generally necessary to monitor the viscosity of the ink during the printing process. This is particularly important in gravure printing, because gravure printing mostly uses low-viscosity solvent-based inks, the solvent evaporates quickly, and the viscosity is easy to change. However, flexographic printing is very different from gravure printing. When discussing the composition of water-based inks, I mentioned "amine", which is a solubilizing resin, which determines the pH of water-based inks. Generally, the pH range of water-based ink should be 8.8 ~ 9.5. At this time, the printing performance of water-based ink is the best and the printing quality is the most stable. Due to the continuous volatilization of amine during the printing process, the operator will also add new ink and various additives to the ink from time to time, and the pH of the ink may change at any time. When the pH value is higher than 9.5, the alkalinity is too strong, the viscosity of the water-based ink will be reduced, the drying speed will be slow, and the water resistance will be poor; when the pH value is lower than 8.8, that is, the alkali is too weak, the viscosity of the water-based ink will When it is raised, the ink is easy to dry, blocking the plate and the anilox roller, causing dirt on the plate surface, and generating foam.
Therefore, the pH value of water-based ink is regarded as one of the most critical factors to control the production process in today's flexographic printing industry. In a sense, the control of pH value is even more important than the control of viscosity. We recommend that users take the pH value and Viscosity is linked for monitoring. This is a new attempt, it is best to prepare a simple pH indicator in addition to the viscosity cup. Operators should not only understand the pH values ​​of various ink additives and their changes, but also strictly follow the technical information provided by the supplier when printing. As for the degree to which the viscosity and pH should be controlled, we believe that the more accurate the better if feasible. Because the water-based ink has only one optimal matching point of pH value and viscosity, at this time, the water-based ink can adapt to the printing machine, anilox roller, ink transfer system, flexible printing plate, substrate, drying system and workshop environment. Composed of an external environment. Experience has shown that when overprinting another color on one color, the viscosity of the ink should be gradually increased and the pH of the ink should be gradually reduced. This will help the drying of the ink and prevent the post-printed ink from making the previously printed dry ink wet again and affecting the print quality.
By the way, the pH range of some special water-based inks is different from ordinary water-based inks. For example, the pH value of gold and silver inks is 7.5 ~ 8.0, and the fluorescent inks are 7.5 ~ 8.3. Types and methods of common water-based ink additives:
1. pH stabilizer
As we all know, the pH value is very important for the stability of the water-based ink, so the printing shop should first be equipped with a pH stabilizer. The pH stabilizer can supplement the amine and water volatilized from the ink transfer system during the printing process, help stabilize the viscosity of the ink, and ensure the printing quality. According to the different substrates, the pH stabilizer is divided into ordinary type and film type. When printing a fine screen, a special pH stabilizer should be used. The general usage of pH stabilizer is to add 1 ~ 2% of the total ink volume every 30 ~ 40 minutes and stir it evenly, or add the stabilizer to the circulating ink pump.
2. Defoamer Generally, an appropriate amount of defoamer is added to the ink before printing to prevent the ink from foaming, and an appropriate amount of defoamer can be added when necessary during the printing process. The amount of defoamer does not exceed 0.5 ~ 1% of the total ink volume each time.
3. Fast-drying and slow-drying agents can be added to the ink according to the actual printing speed of the printer, and the drying speed of the water-based ink can be changed appropriately to obtain a more satisfactory printing effect. Its dosage is 1 ~ 2% of the total ink volume.
4. Lightening agent Under the premise of unchanged pH and viscosity, adding a lightening agent can reduce the color density of a certain ink. Its dosage should depend on the specific situation.
5. Thinner Adding thinner to the ink can reduce the viscosity of the thickened water-based ink without affecting the pH. Its usage must not exceed 5% of the total ink volume.
6. Reinforcer Reinforcer can enhance the adhesion of printing ink or varnish to the printing material, and its dosage is generally 1 ~ 2% of the total ink.
7. Anti-static agent The anti-static agent can effectively prevent the accumulation of static electricity on the printing machine, and its dosage is generally 0.5 ~ 1% of the total ink.
In view of the current situation that various brands of imported water-based inks and water-based inks trial-produced by domestic manufacturers are trying to occupy the market, we recommend that users first familiarize themselves with the various properties of an authoritative brand of water-based inks and the use of corresponding additives. After trying other brands, you should generally avoid mixing the two brands of water-based inks or additives, because different brands of inks or additives have different formulations. We have encountered the phenomenon of precipitation reaction after adding a domestic slow-drying agent to the imported water-based ink.
6. What should be paid attention to when printing non-absorbent materials with water-based ink
When printing non-absorbent printing materials such as film and aluminum foil with flexographic water-based ink, the appropriate printing ink should be selected first. In the past, gravure printing used benzene ink or alcohol ink, and the surface tension of the solvent was below 28 dynes per centimeter, so for general films, the adhesion of gravure printing ink is not a problem, and some films do not even need to be discharged in advance. The process can be printed. But for water-based ink, the adhesion performance of the ink is critical. In order to avoid losses, a large number of tests are generally done before formal printing in order to select inks with better adhesion. The surface tension of the water-based ink or UV ink relative to the printing material should be kept above 38 dynes per centimeter. You can use a dyne test pen to test the surface tension of the printing material. The Dyne test pen is a colored water pen with a felt tip. Draw a wet mark on the surface of the printing material, and then observe whether the wet mark will show a spherical oil film. How long does it take to form a spherical oil film, and To judge the adhesion performance of water-based ink on the printing material. The disadvantage of this method is that the test pen is easy to get dirty after being used many times and affect its accuracy.
For users of flexo printing machines that use plastic film as the printing material, they should try to buy those films that have undergone discharge treatment, and a discharge processor (CORONATREATER) should be installed on the flexo printing machine to discharge the film again before printing To ensure the highest surface tension of the film. Because even if the user buys a film that has undergone discharge treatment, when the film is stored for a long time or is stored improperly, the original treatment effect will be weakened until it disappears, affecting the adhesion of the ink. If you choose a film without discharge treatment, it is difficult to make the film have good ink adhesion by a single discharge treatment before printing, and it is difficult to achieve the desired printing effect.
In order to reconfirm the fastness of the ink attached to the printing material, the following tests can also be done after proofing:
1. Scratch resistance test Apply moderate pressure with the nails of the thumb, and repeatedly scrape the ink layer that has been printed and dried on the film several times. If the ink layer shows scratches or the ink falls off, it means that the adhesion of the ink is not ideal.
2. Adhesive tape peel resistance test Use 3M brand 610 or 810 adhesive tape to evenly adhere to the printed sample, and use your fingers to press it on the back of the tape to make it stick firmly, and then grasp both ends of the tape by hand and pull up at a moderate speed. Observe the ink sticking up with tape. As long as there is ink on the tape, it indicates that the adhesion of the ink on the printing material is not good.
3. Dry rubbing resistance test The printed surfaces of the two printed samples are relatively stacked together, and 2 to 4 pounds of pressure are applied to rub repeatedly. If there are scratches or the ink falls off, the ink adhesion is poor.
4. The wet friction resistance test method is similar to the above dry friction resistance test, except that a little water needs to be added between the two prints.
5. Detergent resistance test Drop one or several drops of alkaline detergent on the printed sample. After 15 seconds, use a paper towel or a clean soft cloth to suck it clean, and then wipe it with a medium pressure. The printed graphics and text are as follows Any change indicates that the adhesion of the ink is not good. After the above test, if it is found that a certain ink performance can not meet the printing requirements of the printing material, you should replace other brands of ink, and continue to test until you find a suitable ink.
7. How to understand the flexographic plate making in general
At present, the flexographic plates introduced in China are basically solid photosensitive resin plates, and the thickness of the plates is selected according to the requirements of flexographic printing machines. The common plate thickness is 1.70 mm and 2.29 mm. The flexographic plate making is the process of transferring the pictures and text to the printing plate through the negative picture film, which mainly includes the following procedures:
(1) Expose the plate with ultraviolet light. Its function is to determine the height of the relief on the plate, that is, the depth of corrosion, and to solidify the substrate. (2)
The front of the printing plate and the film are exposed to ultraviolet light to form the printed part of the graphic and solidify it. (3)
The printing plate is placed in a solvent and brushed, the purpose is to brush away the unexposed part of the plate, so that the graphic part is embossed. (4)
Place the printing plate in a dryer to dry the solvent absorbed in the plate as soon as possible to restore the thickness of the printing plate to the original standard value. (5)
The post-exposure and debonding treatment of the dried plate material can further solidify the shoulder and base, and improve the printing performance of the flexographic plate. The high-quality flexographic printing plate should have a print resistance rate greater than 500,000 prints, or even as high as 1 million prints.
8. How to calculate the shrinkage of flexographic film
The amount of shrinkage is only related to the diameter of the plate cylinder (including double-sided tape and plate material) and the thickness of the plate material itself. Here is a formula for calculating the amount of shrinkage (percentage) of the film used in the flexographic version of plane exposure: the amount of shrinkage (percentage) = K / Rx100%.
In the formula, the coefficient K depends on the thickness of the plate used. When the thickness is 1.70 mm, K = 9.89 mm; and when the thickness is 2.29 mm, K = 13.56 mm. R is the printing length of the plate cylinder in mm. If the printing length of a product is R = 235 mm, the thickness of the plate is 1.70 mm, and K = 9.89 mm, the amount of shrinkage = 9.89 / 235x100% = 4.21%.
The design ink draft should be longitudinally reduced according to the above ratio when it comes out of the film, and then made by plate exposure, so that the printed product will meet the size requirements. It should be further explained that when analyzing and estimating in actual production, the printing length The determination of R needs to consider various factors, such as when the plate cylinder gear module is 1/8 inch, the printing length can only be increased or decreased in 3.175 mm steps; other factors include reducing the paper consumption and leaving the sticky version The margin, and the limitations of processing indentation die-cutting tools, etc.
9. How to do the back exposure test
We can first determine the back exposure time suitable for different corrosion depths by doing a back exposure test on the plate-making machine. In order to facilitate comparison, we adopt the method of performing multiple exposures on the same plate with different exposure times. Take a plate with a size of about 320 mm long and 100 mm wide. When performing back exposure on the plate-making machine, we use a red masking strip for partial partial masking. The plate-making machine is exposed multiple times, resulting in five different back exposure times Plate of the area. In addition, a blank of about 20 mm should be left at one end of the plate for the plate washer to hold. Suppose we chose the AV-500 combined plate-making machine made in the Netherlands and GRACE company's flexible plate with a thickness of 1.70 mm. After partial covering and multiple exposures, on the same printing plate we get exposure times of 0, The five parts of 15, 20, 25, 30 seconds, after exposure, put on the drum of the printing plate to wash the plate, about 7 minutes. Then dry in a drying oven at a temperature of 50. c, the time is 1.5 hours. Finally, take out the printing plate and use calipers to measure the four different thickness values ​​of the printing plate, while the unexposed part of the printing plate is left with a hard polyester plate.
Through the above test, you can quickly become familiar with the plate-making machine, and its test results are also of guiding significance for adjusting the corrosion depth of the printing plate. From the above experiments, it can be seen that the length of the back exposure time will affect the thickness of the plate base. Therefore, for different printed graphics, different back exposure times should also be used when making a plate. Taking the 1.70 mm thick flexible plate as an example, the highlights and large solid parts on the printing plate have a deeper corrosion depth (that is, the plate base is thinner), which can reach about 1.0 mm, and the back exposure time is the shortest; The corrosion depth of the ordinary graphic parts is centered at about 0.85 mm, and the back exposure time is moderate; as for the small lines and dots, the corrosion depth should be the shallowest, about 0.63 mm, so the back exposure time needs the longest .
In addition, there are two points worth noting: when the printer switches to another thickness of flexographic version or another brand of flexographic version, the back exposure test must be repeated. As the use time of the ultraviolet lamp is extended, the light intensity will be reduced, and the back exposure time should be adjusted accordingly.
10. How to do positive exposure test
Front exposure is also called main exposure, which forms the graphic printing part of the flexographic version. Appropriate positive exposure and back exposure work together to obtain high-quality printing plates that meet the requirements of various graphic types.
In general, underexposure will cause the bottom of the shoulders around the text to be washed away, affecting the service life of the printing plate; and excessive positive exposure will cause insufficient corrosion, which can easily cause paste and cause waste products during printing. Before conducting the front exposure test, we recommend that the operator prepare a test "sample" specifically for the production of flexographic plates. The "sample" should contain small highlights, ordinary highlights and solids, ordinary graphics, and small The basic types of printed graphics such as lines, characters, and dots, and reflect a certain number of screen lines (such as 150lpi) from 10% high to 100% on the ground are reflected on the "sample". The positive exposure test can be carried out by using "samples" on the plate-making machine through partial masking and multiple exposures. In the initial stage, you can also start with a less difficult business, from easy to difficult, accumulate experience, and fully master the technology of flexible version.
Theoretically, the finer the picture and text, the longer the positive exposure time, but keep in mind the common effect of it and the back exposure. For example, inverse characters require less back exposure and front exposure, while the small dots require a shorter depth of corrosion, so it takes longer time for back exposure and front exposure. After a long time of exploration and practice, the plate-making operator should understand the limits of his plate-making, such as the thinnest lines, the smallest characters, the densest dots, and whether 3% of the dots can "stop", and whether 50% of the dots are highlighted "Open up" and so on.
11. What should be paid attention to after washing and drying, after processing and desticking
As the number of solvent usage increases, the time for scrubbing the plates should be properly extended; the position between the fine brush and the plate drum should be adjusted according to different plates, so as to adjust the pressure of the surface of the fine brush and the plate; if the system is particularly fine The dots should be based on the standard thickness position to further reduce the pressure of the fine brush to prevent the dots from being washed away. The drying temperature is about 50. c, the time is about 1.5 ~ 2 hours; it should be taken out several times during the drying process, check the surface of the plate for solvent spots or other burrs, you can use a clean cloth that does not lose fibers, soak some fresh solvent, and wipe gently The surface of the plate is then put back in the drying oven to continue drying. Plates after post-exposure and debonding can greatly improve printability. The prepared flexographic plate is best placed for 12 hours before sticky printing, the purpose is to make all the residual solvent absorbed into the printing plate evaporate during plate making.
In short, in actual operation, the flexographic plate-making personnel must closely cooperate with the personnel in the ink draft design, film production and printing departments, communicate with each other, and sum up experience and lessons in time to improve the overall level of flexographic printing.
12. How to choose the printing unit
The number of printing units is determined by the user when purchasing the machine according to the specific printing order. The ink delivery system of the printing unit mainly has the following forms: ink roller / anilox roller, ink roller / anilox roller / squeegee or anilox roller / squeegee. The ink pick-up roller is also called the metering roller. The hardness of the surface rubber and the pressure between the anilox roller and the number of anilox roller lines are the main factors affecting the amount of ink transfer. In general, when printing solid prints with thicker colors and the uniformity requirements are not very strict, you can use the ink roller / anilox roller type ink transfer system, but the printing quality of this system is not as good as the doctor blade type. Inking device. Therefore, although the use of a doctor blade will increase the preparation time before printing and increase investment, there are still more and more users choosing printing units with a doctor blade or an ink delivery device.
Because the flexographic plate material is soft and compressible, the pressure between the printing plate and the anilox roller and between the printing plate and the surface of the printing material on the printing unit needs to be able to be adjusted very finely. The adjustment knob usually uses extremely thin threads, and the adjustment in four directions is required to be independent of each other. After fine adjustment, the best condition achieved should be maintained throughout the printing process.
13. How to use and maintain the die cutter correctly
The holding point of the round pressure round die cutter is large investment and easy to damage. During the life of the flexo press, the total investment in the die cutter can be close to the investment in a printing press. The factors that affect the service life of the die-cutting knife mainly include: the type of the printing material that is die-cut, the type of ink printed on the printing material, and the maintenance situation. If the printed matter is printed with metal inks such as gold and silver, the die wear will be accelerated during die cutting.
Store
Choose a cool and dry place to store the die-cutting knife. In order to prevent the blade from being damaged, you can use a nylon brush to brush a thin layer of motor oil on and near the blade. When storing, it is best to use the box provided by the die cutter supplier to ensure that the blade does not contact any part or item in the box. The die cutter can be completely wrapped with foam plastic. The support blocks in the box must be supported on the short shafts at both ends of the die cutter, not on the blade.
transport
When you need to pack and transport, you must use suitable size and strong boxes. Each box only has one die cutter, and the surface of the die cutter is covered with foam. The short shafts at both ends of the die cutter should be covered with wooden blocks with holes, which are fixed in the box to prevent the die cutter from shifting in the box during transportation. The outside of the box needs to be wrapped tightly, and the surface of the box must be marked with "wearable parts" to attract attention.
Lifting and handling
When lifting and transporting in the workshop, cover the surface of the die cutter with a cloth to prevent the blade from being damaged. When installing other parts, it is necessary to prevent the parts from loosening and falling onto the die cutter, otherwise the die cutter will be seriously damaged.
Use and maintenance
When using a die cutter, be sure to use the roll shoulder provided by the manufacturer to wipe the felt, and apply an appropriate amount of lubricating oil daily to keep the surface of the die cutter roll shoulder and the bottom anvil roll clean, and form a thin layer between the two The thin oil film improves the wear resistance of the die cutter roll shoulder and the bottom anvil roll surface. During the use process, we must keep abreast of the wear of the die cutter gear, and replace the gear in time if necessary. Because during processing, the manufacturer intentionally makes the hardness of the die cutter gear slightly lower than the hardness of the bottom anvil roller gear, so that the wear first occurs on the gear of the die cutter. This avoids frequent replacement of the bottom anvil roller gear, which is expensive and difficult to disassemble. This situation is very similar to the relative hardness relationship between the plate cylinder gear and the impression cylinder gear, because it is easier to replace the plate cylinder gear.
When die cutting, remember to apply pressure evenly. A layer of wrap on the surface of the die cutter can reduce the impact, and you can also eject small pieces of shredded paper.
Make a record
It is necessary to develop the habit of making records, including the number of die-cutting, the date when the die-cutting knife is sent back to grinding, the condition of the paper that is die-cut at each work, and the use of metal ink when necessary. With reference to these records, you can know when it is necessary to sharpen the die cutter in today's thick production, and when to order a new die cutter to avoid delays in production or waste.
14. How to determine the screen according to the characteristics of the printed matter
Generally speaking, the quality of the paper is rougher, the speed of the printing machine is faster, and the screen of 80 lines / inch ~ line / inch can be used during plate making, and the printing effect is relatively good. For printing with embossed aluminized paper, corrugated paper, posters, ordinary offset paper and newspaper, etc., screen printing of 80 lines / inch to 100 lines / inch can be more suitable. Copperplate paper, newspapers and other materials are used. Printing trademarks, pictorials, star films, desk calendars, merchandise advertisements, book covers, etc., you can use 150 lines / inch ~ 175 lines * inch screen plate making; use high-grade coated paper, glass cards to print fine picture books, product advertisements, books For high-end products such as covers, illustrations, packaging and decoration prints, you can choose 175 line / inch ~ 200 line / inch screen plate making, in order to achieve a better printing process effect and improve the printing quality of the product.
15. How to adjust the appropriate printing pressure
Excessive printing pressure is the main reason for the increase of flexographic printing dots. The printing pressure is large, the layout is easy to expand and deform due to excessive squeezing, and the ink at the edge of the dot is also easily transferred to the printed sheet, causing printing paste, ghosting or dot enlargement. The production process shows that the use of smaller printing pressure is an important measure to improve the printing quality of the dot. Therefore, the printing pressure should be adjusted reasonably, and the pressure should be lightened as much as possible. The actual control of the pressure generally controls the compression of the printing plate within 0.1 mm. Usually, the pressure is relatively smaller when printing fine screens, and the pressure is higher when printing on the ground. The flexibility of the flexographic plate is low, it is more uniform when it contacts the bearing, and the ink color printed is also more uniform, but the dots increase more, and the level of the image is poorly reproducible. Therefore, when printing smooth substrates and halftone prints on the surface, the hardness of the printing plate is required to be higher, while when printing substrates with rough surfaces and on-site printing, the hardness of the printing plate is required to be lower, to improve the product's Print quality.
16. Adjust the ink supply pressure
If the ink supply pressure is too high, on the one hand, it is easy to make the screen dots wear and deform, on the other hand, the ink on the ink roller is easy to form a squeeze phenomenon on the plate surface, so that the ink layer on the plate surface is uneven or paste defects occur. If the pressure of the ink roller is too light, it is easy to cause uneven and insufficient ink receiving on the layout, making the dot printing unclear. Therefore, the contact pressure between the ink roller and the plate cylinder should be adjusted.
17. The choice of ink
The ink used in flexographic printing is a low viscosity ink similar to gravure printing. According to the quality requirements of the product, different inks and solvent inks should be selected for printing. For example, in order to obtain a printed product with good heat resistance and toughness imprinting, an ink based on acrylic resin can be used as the binder. If the printed product has good gloss, an ink based on a polyurethane resin can be used as the binder. As another example, when printing on polyethylene-based non-absorbent films, you can choose quick-drying, good adhesion ethanol solvent ink; if you print on corrugated cardboard, books, and newspapers, you can choose those that are easy to clean and have no environmental pollution. Water-based ink.
18. How to print large area solid color
The packaging boxes of household appliances are large in volume and large in printing area, and many of them contain large pieces of solid ground. The color brightness is high, and some require overprinting in the design. This requires that when printing, it is necessary to ensure that the large area of ​​the ground is well inked and used. Press lightly to ensure that the quality of the overprint is good and the strength of the cardboard is not damaged; both large solid thick ink film (generally more than 80µm) must be handled to achieve the required color brightness and saturation, and small text, Thin lines and screened images are clear and moist. It is indeed not easy to balance the four.
In order to ensure a good printing effect on a large area of ​​the field, the large area of ​​the field, small text, thin lines, and screen image parts can be made public. The hardness of the plate material selected for the large solid part should be HS40, and the hardness of the plate material selected for the small text, thin lines, and screen image parts should be HS50-HS55. Note that the plate thickness should be consistent. The cushion material is replaced by a foam cushion, and the base is mainly a thin polyester base. In this way, although the large area of ​​the field and the small text, thin lines, and screen images are printed on the same layout at the same time after printing, the actual printing pressure obtained during printing is different. The printing pressure on the large area of ​​the field is less than The printing pressure on small text, thin lines, and screen image parts is not only leak-free, but also the corrugated paper has no sense of depression. This is the opposite of the thinking that the large-scale field pressure on the ground must be slightly larger in order to be printed.
The key here is that the flexibility of the printing plate is fully utilized: although there is slight pressure on the large solid area, but the kiss is full, the ink color printed is very good, and there is no hard mouth; while the small text, thin lines, screen image parts The printing plate has high hardness, and the dots are not easy to expand and deform.
In fact, we have all experienced this: when printing large areas on the ground, if the pressure is too high, it will inevitably cause the display flute or flute to leak.
19. How to deal with overprinting and overprinting
Most large-area field printing requires thick ink film, which is difficult for small print.
To solve this contradiction, large-area field and small-area graphic can also be made separately, but two-version same-color overprinting is used during printing. Large-area solid plate is used for thick ink, and small-area graphic plate is used for light ink, but they cannot be too different Large, lest the hue differ too far. By taking the required printing pressure, you can get the desired printing effect. This processing method is superior to the large area solid ink effect obtained by the alternate sheet printing method.
When overprinting, the viscosity of the subsequent color ink is required to be moderate. Generally, the viscosity of the subsequent color ink is slightly higher, which is preferably controlled at 50 seconds. At the same time, to control the drying speed of the front color, the moisture of the cardboard must also be low.
In the drying process of ink, volatile drying and soaking drying are carried out at the same time. The thickness of the printing ink layer is real-time, and the volatile drying is often carried out very slowly, but the infiltration drying cannot be completed completely, which will inevitably affect the subsequent color overprint. At this time, according to the level of the PH value of the ink, stabilizers or ethanol can be added appropriately to adjust the water ink to dry faster, so as to prevent the two colors from sticking and overlapping colors. If necessary, another printing machine can also be used for overprinting. At this time, the pre-color ink has been dried, and overprinting is easier.
20. How to match the anilox roller for the flexo printing machine
Most printed products have solid ground, lines, and continuous tone images. In order to meet the needs of various printed products, users must not adopt the method of installing several anilox rollers with several printing units on the flexo printing machine.
Take the narrow-width unit type flexo printing machine as an example. At present, most of the domestic introductions are 6 + 1 type, that is, 6 color groups are designed for multi-color printing. The last unit can be used for printing and UV coating.
We recommend that for prints that do not exceed 150 lines, this 6 + 1
The flexo printing machine should be equipped with 9 anilox rollers. Among them, four 700 lines, an ink layer thickness of 2.3BCM (1 billion cubic micrometers per inch), 60 ° anilox roller is used for gradation printing; 3 360 ~ 400 lines, BCM6.0, 60 ° anilox The roller is used for solid plate printing; 2 anilox rollers of 200 lines, around BCM15, 60 ° are used for gold printing and glazing.
If you use water-based gloss oil, you should choose 360 ​​line anilox roller, so that the oil layer is slightly thinner, and will not affect the printing speed due to the problem of drying of the gloss oil. Water-based gloss oil does not have the special smell of UV gloss oil.
The position of the anilox roller during printing can be determined after testing and comparison. The thickness of the ink layer that the operator can observe during the test mainly depends on the number of lines and the BCM value of the anilox roller.
Twenty-one, what problems should be paid attention to in the process of using the anilox roller
Laser engraved ceramic anilox roller is a high temperature and abrasion resistant coating material in aviation and aerospace, which is engraved by laser according to a certain density, depth and certain angle and shape. The characteristics of this anilox roller are high cost and wear resistance. If used properly, its life can be up to several years; if used improperly, not only the life will be shortened, but also the anilox roller will be scrapped. In the use process, the position of a certain anilox roller on the printing machine depends on the specific print. Different prints have different positions of the anilox roller, so the anilox roller is often replaced during printing.
At present, most of the narrow-width machines are solid steel anilox rollers, which are very heavy. When loading and unloading the anilox roller, care should be taken to avoid touching the surface cover of the anilox roller with other metal objects. Because the ceramic coating is very thin, it is easy to cause permanent damage after collision. In the process of printing and cleaning the machine, the ink should be avoided from drying on the anilox roller. The special detergent recommended by the water-based ink manufacturer should be used. The stainless steel brush should be used for cleaning, to ensure that the cleaning is clean and thorough. And develop the habit of frequently using high magnifying glass to observe the anilox roller net hole. Once the ink is found to deposit on the bottom of the net hole and there is a trend of increasing gradually, it should be cleaned in time. If the above method does not work, it can be treated by ultrasonic or sandblasting, but it must be carried out under the guidance of the anilox roll manufacturer. Under normal conditions of use and maintenance, there is no need to worry about the wear of the anilox roller. The parts that are easy to wear in the ink transfer system are mainly squeegee blades. In contrast, the wear of the anilox roller ceramic coating can be said to be minimal. After the anilox roller is slightly worn, the ink layer will become thinner.
22. Cleaning of Anilox Roller
在网纹辊出现的质é‡é—®é¢˜ä¸ï¼Œå…¶å®žé™¤å°‘æ•°æ˜¯å› å…¶ä½¿ç”¨æ—¶é—´è¿‡é•¿ï¼Œé€ æˆä¸¥é‡ç£¨æŸå¤–，ç»å¤§å¤šæ•°æ˜¯ç”±äºŽå¯¹ç½‘纹辊的清洗ä¸å½“或清洗ä¸å½»åº•é€ æˆçš„。如何ä¿æŒç½‘纹辊的良好清æ´çŠ¶æ€,对ä¿è¯å°åˆ·è´¨é‡è‡³å…³é‡è¦ã€‚
网纹辊的清洗å¯åˆ†ä¸ºæ—¥å¸¸æ¸…洗和周期清洗，最é‡è¦çš„是日常清洗，æ¯å°åˆ·å®Œä¸€ä¸ªå°ä»¶å°±åº”尽快清洗网纹辊，除掉网纹辊上残余的油墨。任何一ç§èƒ½ä»¤äººæ»¡æ„的网纹辊清洗系统，都必须åšåˆ°åœ¨å½»åº•æ¸…除æ¯ä¸ªç½‘穴底部的残墨颗粒ç‰æ®‹ç•™ç‰©ï¼ŒåŒæ—¶ä¿è¯ä¸æŸå网穴的网墙。
ç›®å‰ï¼Œç½‘纹辊的清洗工艺主è¦æœ‰ç‰©ç†æ¸…洗法和化å¦æ¸…洗法。下é¢ä»‹ç»å½“å‰å¸¸ç”¨çš„å‡ ç§æ¸…洗方法和æ“作è¦é¢†ã€‚
Aã€ç‰©ç†æ¸…洗法
物ç†æ¸…洗法有介质喷射冲洗法（包括å°è‹æ‰“喷洗法ã€å¹²å†°å†²æ´—法ã€å¡‘料细ç 喷洗法ã€é«˜åŽ‹æ°´å†²æ´—法），超声波清洗法，激光清洗法。
â‘´å°è‹æ‰“粉喷洗法。
这是一ç§ä½¿ç”¨å°è‹æ‰“ç²‰ï¼ˆç¢³é…¸æ°¢é’ ï¼‰å’ŒäºŒç¢³é…¸é’ é…制æˆçš„粉状清洗介质，é 喷射力清除网穴内干结的残留油墨ã€æ ‘è„‚ã€æ¶‚布料ç‰ï¼Œè¾¾åˆ°æ¸…洗的目的。其优点是：低压喷洗，一般使用0.4MPa的安全压力。æ¤å¤–，å°è‹æ‰“粉的质地比网纹辊表é¢æ¶‚层柔软得多，颗粒较å°ï¼Œå¯è¿›å…¥ç½‘ç©´ä¸ï¼Œæ¸…洗效率较高，åˆå¯ä¿è¯ç½‘纹辊表é¢å®‰å…¨åŠç½‘ç©´å£ã€‚å°è‹æ‰“细ç 是一ç§æ˜“溶ã€å®‰å…¨æ— 毒ã€æ— 害的物质，有利于环ä¿ã€‚å°è‹æ‰“粉清洗ä¸é€‚于600线以上的ä¸é«˜çº¿æ•°çš„ç½‘çº¹è¾Šï¼Œå› ä¸ºå®ƒå®¹æ˜“å¼•èµ·ç½‘å£åˆ’伤现象。
⑵干冰喷洗法。
这是利用液æ€CO2制æˆå›ºä½“CO2的干冰，在清洗设备内装入已制作好的干冰颗粒或干冰å—，在压缩空气的驱动下，高密度干冰颗粒或细粉éšç€åŽ‹ç¼©ç©ºæ°”冲击到被清洗物体表é¢ï¼Œä»Žè€Œèµ·åˆ°æ¸…洗作用。
干冰清洗的主è¦ä¼˜ç‚¹æ˜¯ï¼šâ‘ 节约费用。干冰在线清洗，节约了大é‡çš„åœæœºæ—¶é—´ï¼Œä¸éœ€å¢žåŠ 劳动力和生产设备，é™ä½Žè´¹ç”¨ã€‚②延长设备使用寿命。③对网纹辊ã€æœºä¸ŠæŽ§åˆ¶å…ƒä»¶ã€å¼€å…³ç‰éƒ½ä¸ä¼šæŸä¼¤ã€‚④安全环ä¿ã€‚干冰清洗ä¸æ±¡æŸ“环境，ä¸äº§ç”ŸåºŸç‰©æ®‹ç•™ã€‚但干冰清洗容易引起陶瓷表é¢çš„爆裂，它ä¸èƒ½ç”¨äºŽæ¸…æ´—é«˜çº¿æ•°çš„ç½‘çº¹è¾Šã€‚å› ä¸ºå¹²å†°æ— æ³•æ·±å…¥åˆ°ç½‘ç©´åº•éƒ¨ï¼Œå½“ç„¶ä¹Ÿå°±æ— æ³•æ¸…é™¤ç½‘ç©´åº•éƒ¨çš„æ‚è´¨äº†ã€‚å› æ¤ï¼Œå¹²å†°æ¸…洗法一般åªé€‚用于清洗网线数较低的网纹辊。
(3)超声波清洗法
超声波清洗是一ç§é«˜æ•ˆçš„清洗方法，但è¦æ³¨æ„的是超声波装置应调到适åˆæ¸…洗的频率上。大多数使用超声波清洗的å°åˆ·åŽ‚还è¦é…åˆä½¿ç”¨å¼ºè…蚀性溶液，以æ高效率，å‡å°‘清洗时间。由于柔性版å°åˆ·å¤šé‡‡ç”¨æ°´åŸºæ²¹å¢¨ï¼Œä»¥è¶…声波清洗法在清洗之å‰æœ‰ä¸€ä¸ªæµ¸æ³¡è¿‡ç¨‹ï¼Œç”¨æ¥è½¯åŒ–陶瓷网纹辊网穴ä¸çš„残墨ç‰ç¡¬æ‚质。这个程åºæ ¹æ®è¾Šçš„大å°åŠæ²¹å¢¨å µå¡žæƒ…况而定，一般è¦0.5～24å°æ—¶ã€‚超声波清洗法利用超声波æ¥äº§ç”Ÿè¶…声波空化现象——以机械形å¼å½¢æˆç²¾å¾®çš„气泡，这些气泡在压力作用下，当接触网纹辊表é¢æ—¶ä¼šå†…å‘爆炸，内å‘爆炸释放的能é‡ä¼šå½¢æˆä¸€ç§æ…动作用或者是摔除作用，将残墨ç‰æ‚质从网纹辊的网穴ä¸æ¸…除掉。
超声波空化强度å—ä¸‹åˆ—å› ç´ å½±å“：
超声波强度。最好å‚考清洗设备生产厂商推èçš„è¶…å£°æ³¢å¼ºåº¦æ ‡å‡†ã€‚
超声波频率。超声波频率与空化现象的强度æˆå比。频率增大，气泡å˜å°ï¼Œç©ºåŒ–强度亦å˜å°ã€‚一般情况下，选用最å°é¢‘率4万赫兹所生æˆçš„气泡就å¯ä»¥äº†ã€‚
浸泡温度。浸泡溶液的温度一般ä¿æŒåœ¨60℃～70℃较好。
清洗时间。清洗时间是最é‡è¦çš„å› ç´ ï¼Œç½‘çº¹è¾Šç½®äºŽè¶…å£°æ³¢æº¶æ¶²ä¸çš„时间越长，其网穴越容易å—æŸå®³ã€‚许多超声波清洗法采用预浸泡程åºï¼Œè€ŒåŽç”¨è¶…声波清洗5分钟，或时间å†ç¨çŸäº›ï¼Œä»¥ä¿æŠ¤ç½‘纹辊上的网穴ä¸å—æŸå®³ã€‚
(4)激光清洗法
è¿™æ˜¯è¿‘å¹´ç ”åˆ¶å‡ºçš„ä¸€ç§æ–°åž‹æ¸…洗方法,使用带特殊光å¦å™¨ä»¶çš„激光装置æ¥æ¸…洗网纹辊。在清洗系统ä¸ï¼Œæ¿€å…‰è¢«ç½®äºŽå…‰å¦å™¨ä»¶ä¸ï¼Œä»¥ä¿æŠ¤é™¶ç“·ç½‘纹辊表é¢ï¼Œä½†æ˜¯å¯ä»¥è’¸å‘掉网纹辊上的残墨ç‰æ‚质。æ®ç§°ï¼Œè¿™ç§æ¸…洗法å¯ä»¥æ¸…洗最高网线数为1200线/英寸的激光雕刻陶瓷网纹辊，从网穴ä¸æ¸…洗掉干墨ã€èžåˆå‰‚ã€èœ¡ã€ç¡…ã€èšå››æ°¯ä¹™çƒ¯ã€ç‰ˆæ颗粒甚至刮刀颗粒ç‰ï¼Œè€Œä¸æŸå网纹辊上网穴。
在供墨åŠæ¸…洗上，用于å‘å°åˆ·éƒ¨ä»¶å®šé‡ä¾›åº”油墨并自动清洗网纹辊ã€è…”å¼åˆ®å¢¨ç³»ç»Ÿã€æ²¹å¢¨æ³µä»¥åŠæ²¹å¢¨ç®¡ï¼Œæ¸…洗顺åºç”±è®¡ç®—机控制，æ高了效率和质é‡ã€‚
Bã€åŒ–å¦æ¸…洗法
化å¦æ¸…洗法也称碱性溶剂清洗法，它是将具è…蚀性的碱性（pH值为8～14）清洗剂用涂抹ã€ç‚¹æ»´ã€å–·æ¶‚或浸泡ç‰æ–¹å¼å°†ç½‘穴内的残留物软化ã€æº¶è§£ï¼Œç„¶åŽå†ç”¨é«˜åŽ‹æ°´è¿›è¡Œæ¸…æ´—ã€‚æ ¹æ®æ¸…洗剂碱性的强弱，å¯åˆ†ä¸ºå¼ºç¢±æ¸…洗法：清洗剂的pH值为12～14，为高效清洗剂。但它å˜åœ¨å¯¹é‡‘属æ料具强力è…蚀,对人体接触有一定å±å®³ç‰ç¼ºç‚¹ï¼Œå› æ¤ä¸é€‚åˆæŠ—è…蚀性低的网纹辊。ä¸æ€§ç¢±æ¸…洗法：清洗剂的pH值为10～12，是一ç§åº”用éžå¸¸å¹¿æ³›çš„温和型清洗剂，å¯å°†è‰²æ–™åŽ»é™¤ï¼Œä½†å¯èƒ½ä¼šç•™ä¸‹æ®‹ä½™ç‰©ï¼Œä»Žè€Œå½±å“清洗效果。弱碱清洗法：清洗剂的pH值为8～10，属于有效清洗剂。但它容易è…èš€ç½‘ç©´ï¼Œé€ æˆç½‘ç©´æŸä¼¤ã€‚
由于化å¦æ¸…洗法的清洗剂渗é€æ€§è¾ƒå¼ºï¼Œå¯¹1000线以上的网纹辊的网穴也å¯æ¸—é€åˆ°åº•éƒ¨ï¼Œå› æ¤å…·æœ‰è¾ƒå¥½çš„清洗效果，应用较广。
化å¦æ¸…洗法一般å¯åˆ†ä¸ºåŒ–å¦æº¶æ¶²æµ¸æ³¡æ³•å’ŒåŒ–å¦æº¶å‰‚刷洗法。
a.化å¦æº¶å‰‚浸泡法
该法需è¦ä¸“用设备，先用化å¦æ¸…洗剂æ¥æº¶è§£ç½‘ç©´ä¸æ®‹ç•™çš„油墨ç‰ç‰©è´¨ï¼Œç„¶åŽå†ç”¨é«˜åŽ‹æ°´æµæ¥å†²æŽ‰å·²æº¶è§£çš„残留物。æ“ä½œæ—¶é¦–å…ˆå°†ç½‘çº¹è¾Šæ”¾ç½®åœ¨æ¸…æ´—æœºå†…ï¼Œå¹¶åŠ å…¥æ¸…æ´—å‰‚ï¼Œå°†ç½‘çº¹è¾Šå…¨éƒ¨æˆ–éƒ¨åˆ†æµ¸æ³¡åœ¨æ§½å†…ï¼Œæ¸…æ´—å‰‚çš„æ¶²é¢é«˜åº¦ä»¥ä½¿ç½‘纹辊的1/2～1/3è¢«æµ¸æ³¡ä¸ºå‡†ï¼Œå°†æ¸…æ´—å‰‚åŠ çƒè‡³40℃～60℃度，网纹辊在ä¸åœè½¬åŠ¨çš„状æ€ä¸‹æ¸…æ´—2å°æ—¶å·¦å³ï¼Œè®©æº¶å‰‚溶解软化干涸的油墨，然åŽç”¨é«˜åŽ‹æ°´å–·å°„回转的网纹辊，去除清洗液和已被溶解的油墨ç‰æ®‹æ¸£ï¼Œæœ€åŽç”¨é«˜åŽ‹æ°”体进行干燥。但æ¤æ³•å˜åœ¨ä¸€ä¸ªæ¸…洗废水的处ç†é—®é¢˜ï¼Œåº”é…备一个分离装置，把水从残墨与化å¦æ¸…洗剂ä¸åˆ†ç¦»å‡ºæ¥ã€
b.化å¦æº¶å‰‚刷洗法
化å¦æº¶å‰‚剂刷洗法就是将化å¦æº¶å‰‚喷射在网纹辊表é¢ï¼Œæ ¹æ®ç½‘纹辊æ料选用适宜的细密刷å(陶瓷网纹辊用ä¸é”ˆé’¢ä¸å°åˆ·ï¼Œé‡‘属网纹辊用铜ä¸åˆ·å)，åå¤åˆ·æ´—。 This method is only suitable for cleaning the anilox roller of coarse wire.其优点是设备简å•ï¼Œæ“作方便，æˆæœ¬ä½Žå»‰ï¼Œæ¸…洗容易，ä¿æŠ¤çŽ¯å¢ƒã€‚å…¶ç¼ºç‚¹æ˜¯æ— æ³•æ·±å…¥åˆ°ç½‘ç©´ä¸åˆ·æ´—，很难清洗墨穴底部的污垢åŠç§¯å¢¨ï¼Œæ‰€ä»¥æ¸…æ´—ä¸å½»åº•ï¼Œä¸èƒ½æ¢å¤ç½‘穴容积。
二å三ã€å°åˆ·æœºåˆ®å¢¨è¾Šçš„选é…
很多å°åˆ·äººå‘˜è®¤ä¸ºï¼Œå°åˆ·è´¨é‡å¥½å的主è¦åŽŸå› 在于网纹辊的线数和质é‡ï¼Œè€Œå¿½è§†äº†åˆ®å¢¨è¾Šçš„硬度和ä¸é«˜ã€å°åˆ·æ»šç’的平衡度ç‰å…¶ä»–åŒæ ·é‡è¦çš„å› ç´ ã€‚
刮墨辊对于油墨的å‡åŒ€ç¨‹åº¦ã€ç½‘点åŠç»†å¾®æ–‡å—å°åˆ·çš„清晰度起ç€å†³å®šæ€§ä½œç”¨ã€‚250线的陶瓷网纹辊如果é…上硬度35°的橡胶辊，å°åˆ·ç½‘点和较å°çš„å—体åŠçº¿æ¡æ—¶éžå¸¸å›°éš¾ï¼Œå› 为比较软的胶辊使转移到网纹辊上的墨层较厚，但180线的钢辊é…上硬度为75°和光æ´åº¦ä¹Ÿè¾ƒé«˜çš„胶辊，ä¸ç®¡æ˜¯å®žåœ°å°åˆ·è¿˜æ˜¯ç½‘点å°å—å°åˆ·éƒ½éžå¸¸è½»æ¾ï¼Œå› 为硬度较高的胶辊已接近刮墨刀的刮墨效果。
如果将国产å°åˆ·æœºçš„部分油墨胶辊的硬度由原æ¥çš„35°±3æ高到75°±3，生产效率和å°åˆ·å“è´¨é‡ä¹Ÿä¼šéšç€æ高。
二åå››ã€çº¸ç®±æŸ”版å°åˆ·ä¸åˆ®å¢¨åˆ€å¯¹å°åˆ·å“è´¨é‡å½±å“
Squeegee pressure, sharpness, and contact position with the plate all have an impact on print quality. According to actual needs, reasonable adjustment of these factors can solve many problems in printing.
（1）压力
The factors that affect the pressure of the doctor blade are the size of the cylinder pressure, the difference between the hard and soft blades, the angle at which the doctor blade crosses the printing plate, etc. The greater the slope, the greater the pressure.过大的压力会é™ä½Žæ²¹å¢¨çš„转移率，对å°ç‰ˆã€åˆ€ç‰‡çš„磨æŸè¾ƒå¤§;过å°çš„压力容易å‘生è„版或出现刮刀线。
（2）刀的锋利度
刀的锋利度å–决于是å¦æ–°åˆ€ã€ç£¨åˆ€æ—¶çš„刀刃角度ã€æ‰€ç”¨ç ‚纸(油石)çš„åž‹å·ç‰ã€‚ The appropriate sharpness of the knife should be effective to scrape off the ink without generating wire. Too sharp scrapers are often prone to traces of wire, while at the same time wearing plates.
（3）刮墨刀接触å°ç‰ˆçš„è·ç¦»
刮刀接触å°ç‰ˆè·ç¦»çš„å‡å°‘有利于æ高油墨转移率，但åˆå®¹æ˜“产生è„版;å之å¯ä»¥æœ‰æ•ˆåœ°è§£å†³è„版，并é¿å…一些细å°çš„线痕，但会é™ä½Žæ²¹å¢¨è½¬ç§»çŽ‡ã€‚
（4）刀的平整度
The flatness and warpage of the knife mainly depend on the installation method. Of course, it may also be related to the adhesion of foreign objects in the slot of the knife holder or on the blade and the lining.
When the flatness of the knife is poor, some bead-like marks will appear on the edge of the printing surface, or some intermittent line marks will appear from time to time. Some people think that the above phenomenon will only occur if the ink is rough and the ink flow is not good. In fact, this situation can also occur when the knife is uneven.
（5）ã€åˆ®å¢¨åˆ€çš„移动
The movement of the doctor blade to the left and right has an important effect on reducing the doctor blade line, improving the doctor blade utilization rate, and reducing the abrasion of the plate. If the squeegee moves abnormally, you should try to improve it.
When line marks appear in printing, one is causing plate damage, and the other is that the scraper is not sharp. However, another reason is that foreign objects are stuck behind the blade. The solution is to move the squeegee back and forth up and down in order to get rid of the sticky objects. If you can't get rid of it, you can only stop and wipe the squeegee.
Another problem is related to the squeegee, and many people misunderstand that it is caused by ink. This refers to the occasional appearance of dozens of irregular line marks of varying lengths, which look like they are piled up by ink. It is different from the scraper line. It is not continuous, but sometimes there is no time. This is actually the scraper. The pressure is too low or the scraper is not sharp enough.
Several indicators of the above scraper have both differences and similarities. When solving specific problems, one of them can be used, and sometimes it needs to be comprehensively applied to completely solve the problem.如，当出现一些间æ–的墨线时，既å¯ä»¥åŠ 大压力解决，也å¯é€šè¿‡ç£¨åˆ€è§£å†³;当出现较严é‡çš„è„ç‰ˆæ—¶ï¼Œå°±éœ€å‡ æ–¹é¢ç»“åˆèµ·æ¥è¿ç”¨äº†;一è¦ä½¿ç”¨é”‹åˆ©çš„刀片，二è¦åŠ 大压力，三è¦å¢žåŠ 刮刀与接触片é¢çš„è·ç¦»ã€‚
When the squeegee is seriously worn and cannot be ground with sandpaper or oilstone, it can be honed with a special sharpener so that it can be reused several times, greatly reducing the cost of the squeegee.
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