Printing color sequence selection principle
Sheet-fed printing is a single color in a certain order to present color effects, in order to obtain good prints, we must rationally arrange the color printing sequence, comprehensive consideration of the brightness of the ink, transparency, viscosity, viscosity and original tone, paper properties, After the layout structure and machine type, the printing color sequence should be arranged.
Job Pre-college
Modern high-speed multicolor offset presses generally have a central console operating system. Through this system, the next job can be pre-calibrated during the print job. Due to the different system program design of each model, the pre-school content There are also differences. All pre-set information is stored in the center console. When needed, the information is transferred and sent to the printing equipment. The equipment will be adjusted according to the instructions so that the work can greatly increase the production efficiency.
Plate disassembly and calibration
Sheet offsets for sheetfed offset presses mainly come in two forms.
1. Fixed folder
To disassemble the plate of this type of plate, use the line-positioning method to ensure the accuracy of the plate. The horizontal line of the new version to be installed is extended to the edges of both sides of the plate, and the vertical line is extended to the port. Before the old version is removed, an extension line of the same line as the new one is drawn to the edge of the plate cylinder and the stencil clamp. The steps for installing the new plate are as follows.
(1) Adjust the jaws of the eaves and drag pins to the desired position, draw the adjustment of the line to the line position, and center the folder without lines.
(2) Insert the cornice of the plate into the retrace plate and align it with the horizontal and vertical lines drawn.
(3) Tighten the clamping screws at both ends and tighten the clamping screws one by one.
(4) Insert the lining, jog the machine, and wrap the lining with the printing plate together on the plate cylinder.
(5) Fold the plate to a suitable angle, insert the plate, and tighten the plate screws one by one.
(6) Tighten the lag screw of the tow clamp and tighten the retort screw of the stencil clamp so that the plate is tightly packed on the plate cylinder.
2. Positioning nail type clip
Modern multi-color high-speed offset presses mostly use position-hanging clips, and there are manual, semi-automatic, and fully-automated versions. Different machines can be equipped with different loading methods. As long as the positioning pin is positioned accurately, the printing plate is inserted in place. Loading error is generally not large.
3. Plate calibration
Plate calibration is mainly to change the location of the text on the paper, divided into two kinds of manual and automatic.
Quality inspection during printing
Proofreading before printing begins is very important, because printing plate drying, blanket depression, etc. may cause image loss. At the trial printing stage, the amount of water and ink have been changing, the relationship between ink and ink has not been in a relatively balanced state, and the quality of printed products is not stable. Therefore, during the trial printing stage, the sampling should be frequently compared with the printing sample from the delivery section to ensure that the printed product is consistent with the printed sample in the shortest time. The quality inspection during the printing process is also to obtain a consistent quality of the entire batch of products.
Work after printing
After the job printing is completed, it does not mean the end of the printing job, but also follow-up work according to product requirements and machine production arrangements. If the product needs to be reprinted in a short period of time, the storage of the printing plate, storage and recording of the ink volume should be completed. Printed products should be properly marked and samples, samples, and other proofs should be properly kept. When it is necessary to change color or stop production, the cleaning of the machine and the sanitation of the surrounding environment should be done.