In order to print high-quality color calendars, it is necessary to realize effective control of graphic overprinting, ink transfer, layers and other aspects according to the conditions of paper, printing method and printing medium, so as to achieve the printing effect. Color Calendar for overprints, gradients, colors, and more. Quality control metrics for recovery, ink color uniformity, and more.
Ink Balance Control
To properly control the ink balance in actual production, the following points need to be noted.
(1) It is necessary to correctly grasp the relationship between the amount of water, the amount of ink and printing. (2) Master the principle of less water and thick ink. Less water is on the premise that the blank part of the layout is not sticky and dirty; thick ink refers to the appropriate increase in the amount of ink on the basis of less water. (3) Correctly control the fountain solution. Experience has shown that the surface tension of the fountain solution should be slightly greater than that of the ink. It is generally believed that the surface tension of the fountain solution is about 4.0×10-2 to 5.0×10-2N/m, which is conducive to achieving ink balance. (4) The ink is too emulsified, which affects the balance of ink and water. In actual production, the emulsification of the ink is inevitable under the extrusion of the roller, the water roller and the ink roller. However, excessive emulsification of ink can cause a series of problems in printing.
Overprint Quality Control
Achieving good and accurate multicolor overprinting during the printing process is very important for good prints. The types of inaccurate overprinting of the color calendar include irregular deviation of the printed image, partial deviation of the printed image, and regular deviation of the printed image position in the same direction. For various problems, they should be treated differently in production. The reason for the paper itself, the accuracy of the printing press, the printing pressure, the prepress plate making process, including the skills of the operator and the equipment maintenance status of the printing press, may affect the accuracy of overprinting. factor. My company's Roland machine, UNISET60, often suffers from axial misregistration in one of the two PS plates on the same cylinder of the M plate cylinder. In order to improve the registration accuracy, the robot uses scissors to modify the position of the positioning holes of the PS plate to compensate for overprinting. A bug is a solution adopted after analyzing a specific problem.
Color Calendar Appearance Quality Control
The first thing to do in assessing the quality of a calendar is to assess its aesthetics. This requires not only ink color, layout, header density, pictures, registration, but also the look of the calendar.
(1) The layout of the desk calendar is clean and tidy, without pressure, rubbing, scratching, edge printing, etc., without damage, wrinkles, folded corners, and no obvious through-printing. The pinhole is less than 5mm and there is no gap.
(2) The layout is flat and there is no missing printing. No partial ink unevenness or partial ghosting, no partial text fading, no ink streaks or white streaks (water roller printing).
(3) The center of the plate is centered on the left and right, and the deviation is less than the allowable error of 2mm. The head is slightly larger than the foot (1-2mm). The center of the front and back layout is aligned, and the error of up and down, left and right is less than 2mm.
(4) The folding is accurate and neat, the first folding error is less than 2mm, the second folding is less than 4mm, and the cutting is neat and burr-free.
(5) Except for the specified color control points (bars) and necessary bending standard lines, the layout shall not have cross-hairs, CMYK version and other imposition marks.
Printing equipment maintenance
The quality of the color calendar places high demands on the maintenance of the printing press. The maintenance of the printing press is divided into a three-level maintenance system. Here we talk about the focus of the robot's work around the three-level maintenance system.
1. Daily maintenance of the machine
(1) The blanket, water roller and ink roller should be cleaned. (2) Measure the pH value, concentration (conductivity) and water temperature of the fountain solution in the water tank before printing; after printing, clean the water tank and the water tank filter. (3) Check whether each gearbox is short of oil before printing, check whether the wall panel leaks oil when printing, check the oil pipe and oil nozzle after printing, and refuel in time. During printing, check the air pump and clean the motor filter. (4) Clean the paper roller, olive roller, transfer belt, paper guide roller and pinch roller after printing. Prevents wrinkles, smudges and inaccurate overprints when printing. (5) Fill in the shift record. Follow up and respond to the questions explained in the previous lesson,
2. Weekly maintenance of the machine
(1) Clean the water bucket and water pan, check the surface quality of the water roller, and adjust the pressure of the water roller. (2) Check the working state of the cutter, slitting, clamping jaw, folding knife and biting knife, and adjust and replace the wearing parts in time. (3) Clean the folding knife roller, bite roller and guard roller to prevent the product from sticking and dirty during the printing process. (4) Check the oil pump, oil circuit and other lubrication systems. (5) There are plans to remove the ink roller, check the rubber roller bearing, check the surface quality of the ink roller, and adjust the pressure of the rubber roller. (6) Fill in the raw material replacement record.
3. Monthly maintenance of the machine
(1) Cooperate with electromechanical maintenance to check the copper sleeve of the roller connecting rod to maintain the multi-color registration accuracy. (2) Change blankets in a planned way, and use 2 sets of blankets alternately. (3) Clean the water supply pipes of the water tank in a planned way. (4) Clean the gear box in a planned way and replace the lubricating oil. Clean the strainer and oil circuit system.
