Printing common sense

First, how to treat and master (control) printing speed The so-called maximum printing speed offset press, refers to the offset printing machine in the use of the environment, paper, ink and other consumables under the appropriate conditions can reach the maximum speed, rather than the conventional printing speed.
The constant speed of the model is related to its own structure, material and stability. Any equipment with reasonable structure, good material and stability, the constant speed can be mastered, and the other time, the use environment of the equipment is quite different, the status of paper, ink and other consumables are also very different. In this regard, the views of relevant experts Yes: For some imported models such as Germany and Japan, other speed-printable products are controlled at about 80% of their "highest speed", while domestic equipment is generally controlled at about 65%.
If the printing speed is controlled properly, its operation is relatively normal, noise, vibration, wear is small, and the failure rate is also low, which is very favorable for reducing equipment accidents and improving product quality. Regardless of the imported equipment or domestic equipment, the maximum speed is used for a long time. If the equipment is not maintained or repaired in time, sudden equipment loss and accidents can easily occur.

Second, what is the elongation of the blanket Rubber blanket is a kind of elastic object, in the entire clamping, rotation and stamping process will inevitably produce the elongation after the force. In order to transfer the graphic on the printing plate relatively accurately to the paper, the blanket is required to have a small elongation during the entire printing process and must be uniform.

1, stretched tightly, the smaller the elongation during the printing process, the graphics and the size of the change is also small, but stretched too tight, it led to an increase in the amount of plate friction and plate life is reduced.
2. If you stretch too much, the elongation will increase, and the amount of friction on the layout will be small, which will easily cause ghosting (that is, double-version).

How to ensure that the blanket gets the ideal elongation rate?

1. Select a rubber blanket with low elongation, and must pay strict attention when cutting and clamping. Its longitudinal direction (warp direction) must not be parallel to the axis of the drum to prevent its elongation from increasing. The bottom surface of the cloth has arrows and grid lines to mark the longitudinal direction.
2. When overprinting, the tightness of the blanket should be kept unchanged so as to avoid changes in the size of the graphic.

Third, the paper for the paper's expansion and contraction rate and paper deformation causes the paper's expansion rate, also known as the amount of paper deformation, refers to the relative change in the paper's size after wetting and drying, because the increase or decrease in size measurement is often through changes Since the size is expressed as a percentage of the original size of the sample, it is the rate of expansion and contraction of the paper.
Paper fiber is a kind of hydrophilic material, that is, it absorbs moisture and expands, and releases water and shrinks. Therefore, the amount of paper deformation depends on the expansion and contraction of the fiber. This form is mainly a change in the size of the straight line. The reason for the change is that the penetration and disappearance of water between the fibers causes relative displacements between the fibers (change in length and width).
Deformation of paper due to handling:
1. Inadequate hanging and drying of paper before printing, and improper or uneven humidity of the paper.
2, the layout of the water is not enough to grasp, the general reason is too much water.
3, the temperature and humidity in the workshop are not appropriate or are fickle.
4. The management of semi-finished products does not meet the regulatory requirements.

Fourth, what is the printability of the rubber roller and the problem that should pay attention to The so-called rubber roller printing adaptability, refers to the rubber roller in the printing process for the water, the ink adaptability.
Although the rubber roller has good elasticity, but in the long-term printing, due to its continuous high-speed operation and is affected by temperature, pressure and tension, it reduces its elasticity, poor ink transmission, and even produces ink bars, so regular It is very necessary to allow the roller to rest. Once the roller has the defects that affect the printing effect or the aging caused by the long-term use and improper use, it should be replaced in time.