Printing pressure ensures that the lining of the ink embossed body is compressed and deformed

Printing pressure The prerequisite for the full transfer of ink is the compressive deformation of the lining of the printed brochure. In actual production, the control pressure of the walk-behind printing machine is mainly through adjusting the thickness of the lining, selecting the appropriate lining material, etc., and indirectly expressing the printing pressure with the maximum compression amount or the printing width of the lining. In order to grasp the adjustment of the lining, it is necessary to fully understand its series of properties. The lining is a viscoelastic material with unique deformation characteristics under the effect of printing pressure. The compressive deformation of viscoelastic materials consists of sensitive elastic deformation, hysteretic elastic deformation and plastic deformation. Hangzhou brochure design sensitive elastic deformation refers to the immediate deformation of the external force, the external force disappears immediately restitution; the elastic deformation is that there is a gradual deformation of the external force, the external force disappears and will gradually recover, eventually restitution; plastic deformation is External forces are deformed, and external forces disappear and they will not return to their original status forever.

The compression deformation of the lining in the printing process only considers the sensitive elastic deformation, and the color brochure printing does not need to consider the elastic deformation and the plastic deformation. This is because the time for the complete recovery of the elastic deformation is much longer than the time interval between two printings; the plastic deformation of the company's brochure design will be less and less during each loading and unloading of the printing, and finally reach a stable state. Among them, the elastic modulus E value is a measure of the magnitude of the sensitive elasticity, and the E value is large for the material, whereas the material is soft.

The following rules apply to the selection of the maximum compression of the liner λ. Brochure production printing soft lining λ: offset printing machine is about 0.2mm, letterpress printing press is about 0.4mm; hard-packed λ: offset printing press is about 0.1mm, letterpress printing press is about 0.15mm; neutral bag Lining λ is between the soft lining and the rigid lining. In actual production, the promotion of single page printing shall take into account the size of λ according to factors such as the accuracy of the printing press, the fineness of the printed matter, the printing speed, and the quality of the paper.

The thickness of the lining refers to the design thickness of the lining of the printing press. The lining thickness of the offset lining is the size of the diameter of the cylinder. The reduction of the diameter of the cylinders of different types of offset presses varies greatly and varies from 2 to 4 mm. The lining thickness has little effect on the soft and hard properties of the lining, which is mainly affected by the elastic modulus E of the lining. Leaflets for offset printing companies with offset diameters of about 2mm can only be composed of a blanket plus several liners, which are therefore hard liners; packages with a reduced diameter in the range of 3.0 to 3.5mm Lining a blanket with a 1.85mm thick blanket on the blanket, the backing printing price also allows for the addition of a rubber liner and an appropriate thickness of the liner, or add a layer of felt and a suitable thickness of the liner The λ obtained by the promotional brochure printing is larger, which belongs to the neutral lining. The lining with the reduction of more than 4mm is lining the back of the blanket and can be covered with a rubber pad, a felt or two rubbers. The liner, which has a larger λ, is a soft liner.

The relationship between the printing pressure and the compression amount of the folding printing and the relationship between the printing pressure and the printing width are not constant, and the relationship between the soft and hard properties of the wrapping is different. However, the general trend of the relationship curve is the same. Among them, the shape of the relation curve of the printing pressure and the compression amount is similar to the exponential function, and the shape of the relationship curve between the printing pressure and the impression width of the folding printing press is similar to the normal function.

For the relation curve between the printing pressure and the compression amount in the non-woven bag printing factory in Hangzhou, the harder the lining, the greater the slope of the curve, the softer the lining, the smaller the slope of the curve, indicating the same change in the amount of compression, non-woven There is a large variation in the pressure of the bag-printing hard liner. In actual production, if hard liners are used, great changes in the printing pressure caused by changes in the compression of small liners must be paid great attention. Moreover, no matter whether it is a soft liner or a hard liner, the amount of compression is large enough. At a value, the change in printing pressure is very sensitive and rapid, indicating that the compression of the soft liner is greater than that of the hard liner under the same printing pressure.