Rotogravura Flexografia

ROTOGRAVURE

Rotogravure is mainly used for the high-speed production of large print runs at constant and top quality. The reproductions throughout the print run because the secret of the gravure process lies in the cylinder, becaues of the Gravure process it is used for long term job and for more than 3 colour printing. The image carriers such as gravure cylinders the ink is applied directly to the cylinder and from the cylinder it is transferred to the substrate. Modern gravure presses have the cylinders rotate in an ink bath where each cell of the design is flooded with ink. A system called a "doctor blade" is angled against the cylinder to wipe away the excess ink, leaving ink only in the cell wells, like this the the cells has less time to dry out before it meets the substrate via the impression rollers. Rotogravure printing has one printing unit for each colour, like CMYK or cyan, magenta, yellow and black. The number of units vary depending on what colours are required to produce the final image. Because gravure is capable of transferring more ink to the paper than other printing processes, gravure is noted for its remarkable density range and hence is a process of choice for fine art and photography reproduction

FLEXOGRAPHIC

Flexographic print is made by creating a positive mirrored master of the required image in a rubber material. The image areas are raised above the non image areas on the plate. The ink is transferred from the ink roll which is partially immerged in the ink tank. Then it transfers to the roll whose texture holds a specific amount of ink since it's covered with thousands of small wells or cups that enable it to meter ink to the printing plate in a uniform thickness evenly and quickly. To avoid getting a final product with a inferiror quality it must be ensured that the amount of ink on the printing plate is not excessive. This is achived by using a scraper, called a doctor blade. The doctor blade removes excess ink from anilox roller before inking the printing plate. The substrate is finally sandwiched between the plate and the impression cylinder to transfer the image.