Precautions when operating the Heidelberg four-color offset press
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The Heidelberg four-color offset press features fast printing speed, high multi-color fitting precision and stable performance. But at the same time it is a delicate guy, the printing production environment requires high standards, the power should be stable, the temperature and humidity should be moderate, the ventilation should be good, the operation should be standardized, a little unsatisfactory, it will strike, and please send people to the factory. Maintenance, the cost is very high, so this requires the operator to have a strong sense of responsibility, to strictly follow the operating procedures, to develop a good working habit in the usual work, so that the performance of Heidelberg offset press can be fully utilized .
1. Make daily preparations for work, fully understand the operating status and maintenance of the machine, check the machine for faults, and ensure that the machine is in good technical condition.
2. Receive the operation notice, carefully read the notice content, arrange the printing tasks in the work order in a structured manner, whether to spray powder, how to arrange the printing color sequence, etc., should be aware of it. Accurately input parameters such as paper size and thickness, and adjust the feeder, pull gauge and delivery device. Before printing on the plate, check the appearance quality of the plate. Whether the plate is flat, clean, uniform, no damage, no creases, no scratches, no dirt and ink spots. Understand the layout specifications, graphic content and dot quality, and then preset the ink files and other settings according to the graphic and blank area, and then upload the machine version.
3. Before the overprinting, the paper will be “returned to zero” and pre-inked. After the printing is printed, the assistant will find the rules. At the same time, the collar machine should check whether the printing specifications meet the operation requirements and carry out simple water and ink adjustment. After the overprinting meets the requirements, look for the business supervisor to proofread and sign. After the proofreading is completed, arrange the crew to clean the dirty and blanket, then print a copy, check the dirty spots, and arrange for decontamination after washing the blanket. The ink zone is adjusted through the CP window and the console, the printing ink color is adjusted and the proofing proof is compared. After cleaning the blanket, the master paper should be placed more, and the blanket is cleaned before the official printing is performed.
4. Ink balance control during printing. Ink balance is a dynamic balance that changes at all times. If the amount of ink supplied to the layout exceeds the balance value, the ink will expand toward the blank portion after being strongly squeezed, and invading the blank surface will cause stickiness. On the other hand, if the water supply to the plate exceeds the balance value, when the water roller passes through the surface of the image, it will leave more water on the surface of the image, and then it will be strongly squeezed by the water roller and the ink roller, and attached to the graphic part. The ink layer is deeply emulsified, causing the print to be dull. Moreover, when the water supply amount is too large, the water enters the ink fountain along the inking roller and the squeezing roller, causing a large range of ink emulsification, and finally the printing cannot be performed.
In the printing process, even if the water delivery device is adjusted and operated correctly, it is affected by the shutdown, the temperature and humidity of the printing workshop, the running speed of the machine, the type of ink, paper, and the blank space of the layout. The restriction of the hydrophilic property and other conditions will directly affect the ink and water balance.
To maintain the balance of ink and water, we must do:
1 The temperature and humidity of the workshop should be stable, because the change of temperature will cause the viscosity and fluidity of the ink to change, and the temperature rises to evaporate the water, so that the ink is out of balance. The temperature is preferably controlled within the range of 18 ° C to 22 ° C, and the relative humidity is controlled at 50% to 70%.
2 printing speed should be stable. In production, the machine must run at a normal speed, and the machine will suddenly and slowly slow down, which will make the ink balance uncontrolled.
3 understand the characteristics of different types of paper, ink and other raw materials. The performance of ink and paper used in printing varies greatly. Different papers and inks have different requirements on ink balance. For example, the paper has a tight texture and looseness, and the water content is small. The ink has viscosity, fluidity and pigment particles. The size of the grade. Under the same conditions of printing plate, temperature, humidity, etc., it is necessary to grasp the changes in their properties.
4 dry oil should be used in moderation. Adding dry oil to the ink will accelerate the drying of the ink, but the drying oil will cause the ink to stick. Therefore, the improper use of the drying oil is an important factor that makes the balance of the ink out of control and dirty.
5 pressure adjustment should be accurate. The press must have precise drum pressure, ink roller pressure and water roller pressure. These three kinds of pressures directly determine the balance of ink and water. Under the premise of ensuring that the printing plate is not dirty, the water supply quantity is controlled to be as small as possible, and the water supply quantity and the ink quantity are relatively stable, so as to ensure the printed matter. The ink color is consistent before and after and the printing operation is stable. The size of the ink is selected according to the type of printing material. The smooth paper volume can be slightly smaller, the rough paper can be slightly larger, the machine runs faster, the water volume can be slightly smaller, and the water can be larger at low speed.
5. When the printing task of one day is completed, the task situation and the ink file are stored, and the plate roller is "returned to zero" and the ink on the ink fountain roller is withdrawn, and the ink anti-drying agent is sprayed. Select the unit to be cleaned on the cleaning page and set the speed of the car wash. When washing the car, prepare the car wash water and two bottles filled with water, and add a small amount of water to the ink roller while pouring a small amount of car wash water. This can not only wash the paper roller and dust on the ink roller while cleaning the ink roller, but also reduce the amount of car wash water and car wash time, not only reduce the production cost, but also maintain the machine and keep the machine always In good working condition.