Electrostatic digital printers and print quality assurance measures
Due to its advantages such as short printing cycle, one-off printing, on-demand printing, and personalized printing, digital printing has been rapidly developed and applied in recent years. The business scope is becoming wider and wider, and business volume is increasing. However, as far as the author's city (Yiwu) is concerned, the overall level of digital printing quality is not high, and the overall professional quality of practitioners is not high. However, with the improvement of people's aesthetics, the quality requirements of printed matter are getting higher and higher. This requires digital press operators to master the corresponding operating skills and ensure the printing quality. The author takes the electrostatic digital printing machine as an example to share the accumulated print quality improvement in the work and to cope with the printing failure experience.
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Experience 1: Solutions for Electrostatic Digital Printing Machines That Cannot Run Full Versions
Electrostatic digital printers cannot print full plates. Even if bleeding is set, the paper will have 3mm to 5mm white borders. This is determined by the nature of the electrostatic printing. The electrostatic digital printer uses toner to print and the toner is heated. Before fixing, it is flat on the substrate. If the full version can be used, the toner will spread to the edge of the paper. The jitter during the printing will cause the toner to spill, causing the print product to be dirty and other faults.
Therefore, when printing on the same size paper as the original document, the final finished product size is often smaller than the size of the original document provided by the customer. For example, if the customer provides a document of size A3 (297mm x 420mm), it is printed on a regular A3 size paper. Each side will have a white edge of about 3mm, and the finished size of the white edge will be 291mm x 414mm. This is not a problem when printing a single page, but when printing magazines and publications of a certain thickness, it is necessary to pay attention to the design of the cover size and the selection of the cover paper size. I have encountered such an example, the customer printed 50 publications, the internal text 310 A4 format, quantitative 70g/m2 offset paper, the cover quantitative 200 g / m2 coated paper, the text printed after the book The thickness of the core is 16mm. The cover manuscript provided by the customer is 297mm x 420mm. Taking into account the thickness of the book block, the width of the cover manuscript has been corrected, the width has been enlarged to 436mm, and the cover has selected 297mm* 440mm coated paper, due to the printer can not print full version led to a 6mm blank, printed width of the cover picture is 434mm, cut the book when the incision is cut off 2mm ~ 3mm, the cover just barely white, and Will not cut off the cover too much caused the lack of graphics.
Experience 2: Color Protection Measures for Printed Materials
1. Color management. The restoration of color is the core of printing and copying. The most ideal state is that the consistency of color can be maintained from the input of the manuscript to the output of the printed matter. This requires the color unity of the input devices and the output devices involved in the entire process. The original intention of color management is to generate ICC profiles for all input and output devices. The PCS connection space in the color management system translates ICC profiles for interpretation to achieve unity of color among devices. However, as far as the current situation is concerned, most digital printing companies are not particularly demanding and inconvenient because of customer requirements. They rarely do color management. Even if they do, there are no more professional personnel who are responsible for color management. Instead, they have to ask the printing press sales staff. Software engineer to do it. However, in the following two cases, color management must be performed. First, digital proofing, because this proof draft will usually be used as a trace for offset printing. If the proof draft itself has too large a color difference, it will not be able to bring accurate results for follow-up large-volume printing. Standard; Second, when small-batch processing, it is difficult to ensure the consistency of product color without color management, resulting in greater losses. Color management must be assigned to someone who is responsible for it, and it is too dependent on software engineers that it can seriously affect production efficiency and it is difficult to make high-quality products.
2 school color. For many companies, not doing color management may have little effect on the product, but if you don't even do color correction, then the product that the company prints will certainly be very different from the color of the original, especially when printed in bulk. Unstable, before and after the color difference will be larger. This is because the digital press is affected by the environment, the performance is unstable, the replacement of parts, change the paper model, etc., the color will continue to change, if there is no calibration, the stability of the color will not be controlled, the color correction is mainly to stabilize the printer s color.
Take the Fuji Xerox Ve rsant T M2 1 0 0 color digital printer as an example. During the color correction, the color target is measured by the EFI - 2000 colorimeter. The input and output curves are generated, and the target curve is used as the difference. Value operation, adjust the output color. Regular school coloring is to draw the curve of the input and output of the machine frequently so as to match the target value constantly to stabilize the color. If the color is not corrected often, there will be a large difference between the measured value and the target value curve, which not only can not stabilize the color output, but also can cause color gradient difference, affecting the color output quality and other issues. Therefore, if the conditions permit, you must regularly do the school color regularly, the higher the frequency every day, the better. It is best to do a color correction before printing in large quantities. Precautions when coloring:
1 school color according to their own use of paper type and quantitative color correction, rather than randomly choose the server's own curve paper calibration; 2 do not start a school on the color, you can print some of the color requirements are not high Document, after the standby is stable and then do the color correction work; 3 color correction, need to put 4 to 6 pieces of white paper below the measurement color target to prevent light transmission; 4 is not the color curve can be directly applied , To check whether the measured value is reasonable, the first curve is smooth, can not have too much fluctuation, and the D-max value is not less than 10% of the target value.
3 . Edit the curve. Of course, if you are familiar with the chromatogram, input and output curves, tone, etc., you can directly edit the curve in the output profile according to the current color output of the printing press to correct the color output of the current printer. It is recommended that newly edited curves should not be directly applied to the color management process, but should be applied directly to the job when setting the print job properties so that it does not affect other jobs.
Experience 3: Printing quality troubleshooting and solutions
If the printer can print normally, there are no errors, but the screen prints various problems: if a certain color is faded out, a colored line appears on the page, the area in the width of the page becomes lighter, and the page is darker. There are black spots, etc. These can be called print quality faults. You may find the Solutions in the manual.
Lesson 4: Preventing and responding to paper jams
Digital printing machine paper jams are largely related to paper, such as wet paper, curled paper, creased paper, disc tray settings and paper inconsistencies, etc. Therefore, special attention should be paid to paper placement, especially after unsealing. Store the paper in the cabinet as much as possible, wrap the remaining paper after unsealing, and place the paper horizontally to prevent it from curling. Coated paper, especially coated paper, has a relatively large internal stress. If moisture is encountered, multiple paper feeds are more likely to occur, causing paper jams, especially in the rainy season in the southern region of the Yangtze River. This problem is more likely to occur. You can use a hair dryer to blow the air toward the side of the stack to loosen the paper, but the temperature of the dryer cannot be too high, otherwise the paper will curl due to water loss.
Improving the printing quality of printed products is the direction of the company's efforts, and it is also the responsibility of the printing operators. Each printing person should practice, summarize, practice, and promote more at work.