Precautions when operating Heidelberg four-color offset press
Heidelberg's four-color offset press is characterized by fast printing speed, high precision of multi-color registration and stable performance. But at the same time, it is also a squeamish guy. It has high standards for the printing production environment, stable electricity, moderate temperature and humidity, good ventilation, and good operation. If it is slightly unsatisfactory, it will strike and invite the manufacturer to send someone. The cost of maintenance is very high, so this requires the operator to have a strong sense of responsibility, to strictly follow the operating regulations, to develop a good working habit in normal work, so that the performance of Heidelberg offset press can be fully utilized .
1. Make preparations for going to work every day, understand the operation status and maintenance of the machine, check the machine for failures, and ensure that the machine is in good technical condition.
2. Receive the job notice, carefully read the notice, arrange the printing tasks in the job order, whether to spray powder, and how to arrange the printing color sequence, etc., should be aware of it. Accurately input paper size, thickness and other parameters, and adjust the feeder, pull gauge and paper collection device. Before the printing plate is put on the machine, first check the appearance quality of the printing plate, whether the layout is smooth and clean, whether the rubbing is uniform, no damage, no creases, no scratches, no dirt and ink dots, etc. Understand the format specifications, graphic content and dot quality, and then pre-set ink files and other settings according to the graphic and blank area, and then install the version on the machine.
3. Before printing, "reset the printing cylinder" to pre-inking. After the printing sample is printed, the assistant will look for the rules. At the same time, the leader should check whether the printing specifications meet the requirements of the operation, and make simple adjustments of water and ink. After the overprint meets the conditions, find the business supervisor to proofread and sign. After proofreading, arrange the crew to clean the dirt and the blanket, and then print another copy, check the dirty spots again, and arrange to remove the stain after washing the blanket. Adjust the ink area through the CP window and the console, adjust the printing ink color, and compare the proofing proofs. After cleaning the blanket, you should put more version paper, and then formally print after the blanket is clean.
4. Water and ink balance control in the printing process. The ink-and-ink balance is a dynamic balance that changes all the time. If the amount of ink supplied to the plate surface exceeds the balance value, the ink will expand toward the blank portion after being strongly squeezed, invading the blank surface and causing stickiness. Conversely, if the amount of water supplied to the layout exceeds the equilibrium value, when the water roller passes through the graphic surface, it will leave more water on the surface of the graphic, and then be strongly squeezed by the water roller and the ink roller to attach to the graphic part. The ink layer is deeply emulsified, resulting in a dull and dull imprint. And when the water supply volume is too large, the water will enter the ink fountain along the inking roller and the inking roller, causing a wide range of ink emulsification, and eventually printing will not be possible.
In the printing process, even if the water delivery device is adjusted and operated correctly, due to the impact of shutdown, the temperature and humidity changes in the printing workshop, the running speed of the machine, the type of ink, paper, and the blank space of the layout, as the number of printing increases, Restrictions such as weakening of the hydrophilic property will also directly affect the water-ink balance.
To maintain the balance of ink and wash, we must do:
①The temperature and humidity of the workshop should be stable, because the change of temperature will cause the change of the viscosity and fluidity of the ink. The increase in temperature will evaporate the water, which will make the water and ink lose balance. The temperature is preferably controlled within the range of 18 ° C to 22 ° C, and the relative humidity is controlled to 50% to 70%.
â‘¡The printing speed should be stable. In production, the machine must maintain normal speed, and the machine will be slow and fast, which will easily make the water and ink balance out of control.
â‘¢Understand the characteristics of different types of paper, ink and other raw materials. The performance of the ink and paper used in printing differs greatly. The use of different papers and inks has different requirements for the balance of water and ink. For example, the paper has a close texture and a loose texture, and a moisture content; the ink has viscosity, fluidity, and pigment particles. The size and so on. Under the same conditions of printing plate, temperature, humidity, etc., we must grasp the changes of their properties.
â‘£ The amount of drying oil should be moderate. Adding drying oil to the ink will accelerate the drying of the ink, but the drying oil will promote the viscosity of the ink. Therefore, the inappropriate amount of drying oil is an important factor that makes the water-ink balance out of control and the dirty version.
⑤ The pressure adjustment should be accurate. The printing press must have precise cylinder pressure, ink roller pressure and water roller pressure. These three pressures directly determine the water-ink balance. On the premise of ensuring that the printing plate is not dirty, the water supply volume is controlled to the smallest possible range, and the water supply volume and the ink volume are in a relatively stable state, so as to ensure the printed matter The ink color is consistent before and after and the printing operation is stable. Choose the ink size according to the type of printing material. The amount of water on smooth paper can be slightly smaller, the rough paper can be slightly larger, the machine runs faster, the amount of water can be smaller, and it can be larger at low speeds.
5. When a day's printing task is completed, store the task situation and ink file, and at the same time "return to zero" of the plate cylinder and withdraw the ink on the ink fountain roller, spray ink anti-drying agent. Select the unit to be cleaned on the cleaning page and set the car wash speed. When washing the car, prepare car wash water and two bottles with water. Pour a small amount of car wash water onto the ink roller while adding a small amount of water. In this way, not only can the paper hair and dust on the ink roller be washed together while cleaning the ink roller, but also the amount of car wash water and the car washing time are reduced, which not only reduces the production cost, but also can maintain the machine well, so that the machine is always In good working condition.
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