¡¡¡¡1.In offset printing, when the paper is pressed by the roller, the width of the sheet and the length of the two corners of the towing place will expand slightly. The greater the pressure, the more the stretching, so that it becomes trapezoidal, resulting in imprecise overprinting, especially in the two corners of the towing part of the paper. Therefore, the theme parts which require high accuracy of overprinting should be arranged at the mouth of the mouth as far as possible in plate making, because the image and text deformation here is small, easy to register.
¡¡¡¡2.the larger the sheet, the greater the amount of deformation caused by moisture content and printing pressure. When printing high precision products with few printing numbers, you can think about how to spell the number of printing plates less. Printing with smaller size paper to improve overprint accuracy.
¡¡¡¡3.When the fiber is wetted completely, the increase of diameter is much greater than the increase of length, so when the moisture content of paper changes, the expansion along the fiber length direction is less than the transverse expansion. In offset printing, on the one hand, the plate or rubber cloth is printed along the axis of the cylinder, the longer the length is when the appearance is new and the same elongation.
¡¡¡¡When using four-color printing process, if there is a larger area of black solid, how to plate making is more conducive to black solid black thick?
¡¡¡¡When using four-color printing process, in order to ensure the correct restoration of tone and color, the ink layer thickness of each color should be strictly controlled. Usually in quadrangular printing, the field density of black does not exceed 1.8, with such density printing large areas of black field, will lack of thick visual effect. The common method is to overprint about 40% of the cyan in a large area of black field. Black field overprint a small amount of cyan, from the hue or black, visual effects will be more substantial. When only one color black is printed on white paper, due to the accumulation of paper wool and pulverized paper on rubber cloth during printing process, or because of other reasons affecting the transfer of ink, white trachoma will appear on the black field, because the exposed is no longer a white paper base, but a cyan dot, compared with black and white contrast, black and green contrast It is not so conspicuous that it can make the black background look more uniform and beautiful.
¡¡¡¡What kinds of regulations are there? What are their respective functions?
¡¡¡¡1.cross or T-line.
¡¡¡¡Polychromatic printing is usually based on whether the cross line is set. Cross lines are the most important and indispensable for printing plates with two or more colors to be aligned. There should be at least two cross lines for the calibration plate. Generally, multiple cross lines will be set according to the size and alignment requirements of the page. If there are only two crosses, they are usually placed in the middle of the left and right sides relative to the paper, and more crosses are used as a reference for calibration. When the width of the paper is very tense, the T-line can be used, so that the vertical edge of the T-line close to the graphic part. A more economical method is to place the cross line on the finished product, but it must be placed in a position that is impossible to see after the finished product is formed.
¡¡¡¡2.The angle line:
¡¡¡¡Corner lines, also known as inner corners, are distributed in the outer corners of the finished pattern and the bleeding on the plate. They are used as the basis for determining the position of the pattern on the paper when the first color plate is calibrated. Generally, the four corners must be printed when the plate is calibrated. In the case of paper sheet tension, can not set angle line, but to ensure that the tangent or tangent corresponding position is on the paper, otherwise will be scrapped because the size of the printed matter does not meet the requirements.
¡¡¡¡3.On the single printing plate, the tangent is located in the four corner of the plate, in the corner line. The position of the edge of the finished product. Some of the more printed plates also have tangents at the boundaries of the imposition. The role of tangent is to specify the location for cutting. After cutting, the corners and tangents are removed.