Printing pressure, also called embossing force, is a term often used in the printing process. The entire printing process is to solve the contradictory process between ink and paper. To transfer the graphic on the printing plate coated with ink to the printed paper, it must exert a certain pressure during the graphic transfer process. The pressure applied is called the printing pressure. People often say: "Without pressure, it is not a matter of printing." This sentence fully shows the importance of printing pressure.
Since printing pressure is so important, is it better that the pressure is greater? Of course not. In general, the appropriateness of printing pressure is often manifested by the quality of printed matter. The pressure should be based on the premise that prints have strong dots, clear graphics, bright colors, and shades of light. The smaller the better.
But the absolute ideal pressure is very difficult, because it varies with technology, experience, model, and other conditions. Nevertheless, the quality of printed products is always the only standard for all ideal pressures.
The size of the printing pressure can be adjusted, and the adjustment method should be: (1) The distance adjustment method of the roller center. By adjusting the center distance between the two rollers to increase or decrease the printing pressure, this is the most common adjustment method. (b) Packing thickness adjustment method. Increasing or decreasing the printing pressure by increasing or decreasing the thickness of the roll lining is the most common and the most important adjustment method. This method is used when the center distance does not reach the specified distance. It is generally best not to move it. It is worth noting that it is easy to increase or decrease the thickness of the lining, which often causes a change in the diameter of the roller, resulting in an unequal circumferential speed. The result will inevitably lead to deformation of the network, misprints, double shadows, wrinkled paper, broken triangles and other faults.
The necessary conditions for obtaining the desired pressure should be: (a) Accurately measure and adjust the center between the two rollers. (b) Accurately calculate and measure the thickness of the lining. Take the old sauna machine as an example. Because the plug gauge between the two rollers is 4.2 mm, then the two roller rubbers and pads are respectively 2.1 mm, the pressure is zero, and the pad pressure is 0.05 mm respectively, then there are 10 wires. Pressure, together with the thickness of the paper, is the ideal pressure. With the increase of the use time, the pressure is gradually reduced. How can it be reduced? The high speed operation, the thickness of the paper, and the longer the time causes the rubber heat to elongate, the fastening pressure is not ideal. In this case, the thickness of the lining is increased through measurement and calculation, and the ideal pressure is reached. Generally, a new eraser is required. Add three layers of cushion to set.
If the printing pressure is too large or too small, the quality of printed products will be reduced. The more serious the printing pressure is, the more disadvantages it brings. When the printing pressure is too large, it will cause: 1 Graphic distortion; 2 Partially over-filled ink, resulting in inconsistent hue of the printed product; 3 Paper pulling; 4 Major deformation of the main pressure-receiving parts and transmission parts of the printing press. The working life of the collar part; 5 Compared with the normal pressure and friction conditions, the wear of the printing plate is accelerated; 6 The imprinting dot enlarges, the printing product level is unclear, and the printing rate of the rubber is affected. The peeling is one of them; 7 Due to the overload of the machine, there are many circuit failures. When the printing pressure is too small, it will cause: 1 the transfer of printing and graphic arts is not complete; 2 network points are not true, and the color is pale; 3 the original defects and defects of printing plates, linings, paper and printing machines are more exposed.
To print a newspaper, you must correctly grasp the pressure adjustment method.