Newspaper printing quality control points of analysis

Many quality problems are caused by a variety of reasons for the production of new problems encountered, newspaper printing quality control is a systematic problem. Need to combine the enterprise equipment, materials, processes and other specific circumstances of a comprehensive analysis, multi-angle thinking, and even need to do some experiments to rule out one by one, in order to find the root cause of the problem and the solution, which also needs to be printed by the enterprise’s technical staff can seriously study, solidly improve the technical strength, in order to comply with the trend of the times, to give play to the advantages of the new equipment, new technologies, to achieve a high level of quality control and quality improvement of the printed materials. Control and quality of print quality enhancement.
Main indicators and control points of newspaper printing quality
Comparison method is the China Newspaper Association Printing Committee newspaper printing quality requirements and testing methods “newspaper quality testing is mainly divided into pictures, inscription, ink, appearance of the four major items. These four items, the current newspaper printing quality assessment of the main standards based on the newspaper printing GB/T179343 national standards. The most representative of the level of quality control is also the most able to open the gap between the newspaper quality rating is the ink colour, especially the uniformity of the black text ink colour and the level of precise control of the amount of ink. Of course, pictures, inscriptions, appearance and other three major items are also essential to the quality of the newspaper quality details control focus. The control of the above items in addition to visual judgement with the printing workers, density measurement, grey balance and ink balance control related to pre-press design control, plate quality control and printing equipment adjustments are also very critical.
Newspaper printing quality there are common problems
Short ink path, newspaper printing is characterised by high printing speed. The use of cold solidification ink, drying by penetration drying method, rubber cylinder mutual embossing cylinder. Ink from the plate cylinder transfer to the substrate on the whole process of ink, wetting solution, plate, blanket and paper, several printing materials and printing press ink transfer device, water transfer device, printing cylinder participation. As a result of high printing speed, ink contact time is short, the suitability of their respective materials for printing and matching each other, not only directly affects the quality of newspaper printing, but also make the ink transfer has become very complex, poorly matched control directly caused by the printing of some of the following problems will occur:

1. ink drying caused by the layout of the rubbing dirty, dirty drag, dirty folder
   Mainly ink on the surface of the print is not dry, the layout of the drag dirty folder dirty is the most common newspaper, the most intuitive quality problems. Ink and printing machine, folding machine or conveyor contact part of the transfer to the paper roller or belt, after accumulating to a certain extent in turn contaminated prints. In addition, the newspaper printed out, the newspaper layout on the graphic is still wet, and then through the folding machine, the keel part of the paper pulling rollers, rows of newspaper rollers, brushes, plywood, belts and other pressure, clamping, dragging of the external mechanical role of the newspaper’s front page and the end of the page, as well as the position of the first folding and second folding of the part of the paper becomes easy to drag dirty, dirty folder, all of these factors have a direct impact on the printed page of the aesthetics. The main reason for the above problems is that the ink itself is poor drying, the ink layer of thick ink is too large, the amount of water is large ink emulsification, the ink layer in the water content is large. To reduce the occurrence of these problems, in addition to controlling the water-ink balance, improve ink performance, adjust the pressure of post-press equipment and other control measures in the printing process, the pre-press link, especially the picture processing link process control is also essential.
   Ink viscosity caused by too much pull paper hair, rubber blanket pile ink 2. paper hair, powder.
   Ink will stick down the paper surface of fine particles, paper surface strength is low and ink viscosity is large. Resulting in paper hair loss and powder, and even tear the paper surface in severe cases. After the paper surface particles peeled off, due to the ink is not stained and cause white spots. From the paper off the confetti sticking to the rubber blanket and printing plate, will accelerate the wear and tear of the printing plate, contamination of the rubber blanket. Paper dust filled in the printing plate on the graphic, will make the print paste, its rolling to the ink bucket, water bucket, will pollute the ink, fountain solution. As paper dust has good hydrophilicity, water adsorption when in contact with the water roller, particles stained with water and then contact with new ink, it is not easy to stain the ink, so that the graphic part of the white spot, if it is a fine paper dust, it will gradually appear at the edge of the image of the pulling hair, resulting in the rubber blanket pile of ink, so that the quality of the printing is reduced. At the same time will cause abrasion, increase the number of rubber blanket, ink roller cleaning, and even interrupt the printing in serious cases. The main cause of this quality problem is the surface properties of paper and ink viscosity. Therefore, the need to monitor the printing performance of these two materials in a timely manner, found that the problem is replaced in a timely manner, the production of the emergence of the need for timely downtime to clean the rubber blanket, printing plate and water, ink rollers. Treatment is not timely may cause rapid wear and tear of the printing plate, can not be printed. Newsprint rotary printing, folding machine for the cutting and folding of the finished product will also produce a large amount of paper dust, so near the folding machine printing tower ink tanks are more likely to be contaminated by dust, thus affecting the purity of the ink.