Letterpress, often occurred fault: the back rubbed against dirty, printing ink, misting, electrostatic, and so on. These faults affect the printing quality, it is necessary to take corresponding measures to eliminate.
(a) smearing on the back
On substrates of ink, glue on the back of another image, smearing. To prevent the back rubbed against dirty, generally in the printer paper department installed powder spraying device, the fine particles of calcium carbonate scattered between the printed sheet. In addition, accelerate the dry ink, reduce the image size crib height, between the image into the absorbency of smearing phenomenon have good paper, bay.
(2) the printing ink
Through printing ink refers to in the back of the printed sheet can see positive impression. To prevent the printing ink, can choose the tightness of paper printing, also can increase the viscosity of the ink, appropriate to reduce printing pressure.
(3) the misting
Tiny droplets of the ink, flying in the air, the phenomenon is called "flying ink", also called ink mist scattered, is a high speed rotary letterpress printing machine of the most common fault. To slow "misting" phenomenon, can increase printing workshop humidity, make appliance has conductive ink such as water-based ink.
(4) electrostatic
Printing process, paper not easy separation, paper on paper accept or losing paper on skewed and misregister, and so on, are likely to be caused by static electricity. Eliminate electrostatic printing, the general electrostatic eliminator is installed on the printer, the printer in the vicinity of air ionization, and the positive and negative on the paper electrostatic neutralization. Can also be near the printer or impression cylinder above, after spraying the right amount of water to eliminate paper static electricity. In addition, humidity increase printing workshop, which is beneficial to eliminate static electricity.
(5), the quality requirements of letterpress printing
Product quality refers to the product and can satisfied people have to share a certain purpose. The use of printed matter is various, different varieties, printing methods vary, according to the technology and equipment, letterpress printing quality should meet the following requirements
(1) promised to error of size requirements detailed product size size of 0.5 mm, the common product is 1.0 mm.
(2) the pressure, ink printing format of average pressure and ink. Text imprinting, fine products are clear and complete stroke break no significant lack of general products.
(3) the average degree of fine products printed pages wide wide average degree should be greater than 15/16, 14/16 general average degree should be greater than the dimension of a product.
(4) set in the period of printed pages, each page is, overprint accurate, the fine product of overprint error is less than 1.5 mm, the common product is less than 2.5 mm.
(5) the appearance of fine products, print the pages and tidy, no paste version, nail, dirty mark, without pen is broken. General products, printed pages and tidy, no significant paste version, nail mark, dirty mark, no significant lack of pen is broken. (Gold Printing Group) |
