Setting and maintenance of offset printing machine
1. Water roller, ink roller pressure setting and adjustment
Products using UV ink printing, water roller, ink roller after a period of time, will produce different degrees of expansion, which will lead to the printing process is very easy to produce water bar, ink bar and other problems. In this regard, we should often check the state of use of the rubber roller, according to the actual use of the water roller and ink roller in the printing color group, the water roller and ink roller pressure to make appropriate adjustments.
2. Offset printing machine lubrication of the transmission bearings
In the offset printing production process, the paper through the embossing tooth row, paper transfer tooth row in the printing color group to pass between, if the transmission bearing lubrication is not in place, it will lead to open tooth bearing wear, affecting the paper in the printing color group to pass between the handover time, which leads to product overprint inaccuracy, especially in the printing of thin paper products, such phenomena will often occur, and the consequences are more serious. In this regard, we should do a good job of offset printing machine transmission bearings lubrication work.
The correct use of printing materials
1. Paper
(1) ordinary paper. Before printing, you must first use a micrometer to measure the exact thickness of the paper, and then enter the corresponding value in the offset press console, and then fine-tune the pressure of each printing color group according to the actual ink color of the print.
(2) positioning paper. Some cigarette packet products, such as "Taishan (Hua Gui)" boxes, small boxes, etc., the paper used in the preliminary design of the pattern, in the printing production, the offset printer must be registered to these patterns. Due to the limitations of the pre-production process, the location of these patterns is likely to be inconsistent, which places high demands on the printing production. The correct approach is: before the paper, the first classification of paper by rule, select the rules consistent paper first printing, different rules of the paper, the front and side gauge adjustment before printing, so that you can effectively reduce the frequent adjustment of rules and bad prints.
2. Ink
In order to eliminate the problem of a large amount of waste of spot-color ink due to the discontinuation of cigarette packet brands, many products of spot-color ink is deployed before the machine with the original ink. Therefore, in offset printing spot-color ink proofing, must accurately record the composition and ratio of each spot-color ink, before mass production, ink blending personnel to determine the correctness of the spot-color ink ratio, and estimate the amount of ink, to avoid repeatedly blending caused by color differences, waste ink and other situations.
3. Fountain solution
The pH value of fountain solution required by our company is 4.8~5.5, other data are: temperature 10~12℃, conductivity 800~1200μs/cm, alcohol concentration 12%~15%, and the pH value of fountain solution must be measured and confirmed regularly whether the data are within the standard range.
4. Blanket lining
Each printing color group blanket lining thickness must be consistent, otherwise it will affect the accuracy of the product overprint, especially in the printing of some overprint accuracy requirements of higher products should pay more attention to this point. But even if the quality of the better liner, there will inevitably be inconsistent thickness, so before using the liner, it is best to use a micrometer to measure the thickness of the liner, to confirm consistency before use.
Confirmation of the printing plate
1. Whether the color block is added to the area other than the finished product on the printing plate
In the production of a large area of color box cigarette packet products, such as "Taishan (Servcorp)," "red gold dragon" and so on, due to the middle part of the color area difference between the two ends, in the offset printing is very easy to produce "ghosting", it is difficult to control Color uniformity. In this regard, pre-press personnel in the plate will usually be made before the finished product on the printing plate plus the color block in the area outside, in order to reduce the gap between the middle part and the two ends of the color area. Practice has proved that this method can effectively reduce the "ghosting" phenomenon.
2. Plate deformation
The plate may be deformed after baking at high temperature, resulting in inaccurate overprinting, especially for some products with fine line overprinting, such as "Taishan (Servo)" small box of cigarette packets. Therefore, for some overprinting accuracy requirements of high print products, should reduce the baking time.
3. The dot angle of the printing plate
In the printing of green products, we must pay close attention to the dot angle of the printing plate. The normal dot angle is usually yellow 0 degrees, magenta 45 degrees, green 15 degrees, black 75 degrees, while the main color of green products is yellow and green, if the angle of these two colors is still 15 degrees, it is very easy to "hit the network" phenomenon, so before production, it is best to confirm the dot angle of each printing plate.
