Gravure Printing

Gravure printing requires a cylinder engraved with hollow “cells” (precisely shaped depressions in the cylinder’s surface) on the order of 0.001–0.002 inch (0.025–0.05mm) in diameter.

Gravure printing is characterized by excellent print quality and high printing speed. Its further advantages are that it involves a simple printing process, accurate ink use, and the flexibility of printing machine structures. Gravure printing, due to several technological innovations, now belongs to innovative technologies. The market of packaging materials is the largest segment of gravure printing, and a further increase is forecast. In this chapter, the bases of gravure printing process (ink transfer, drying, gravure cylinder, doctor blade, impression cylinder, characteristics of the prints) and the characteristics of gravure printing inks are presented. The up-to-date methods of gravure cylinder production and the characteristics of the structure of gravure printing machines are touched on, and finally the areas of the development of gravure printing are dealt with.

Printing and Graphic Arts

Introduction

Gravure printing (also called intaglio, pronounced with a silent g) uses an indented area of the plate from which to print. An excess of fluid is applied to the plate, and the excess is removed. This leaves the raised areas free of ink, and the ink is transferred from the depressed areas. The edges of printed areas have a serrated appearance (under magnification). Web printing with the gravure process is called rotogravure.

Gravure printing is usually carried out as a web process on lightweight (below 40 lb/ream) coated or uncoated groundwood paper with minimal pressure on the plate. Therefore, paper smoothness is very important. Compressible paper and good ink receptivity help print quality. The major components of a rotogravure press include the engraved cylinder (the plate), the ink fountain, a doctor blade to remove the ink from the nonprinting area, and the impression roller.

Fabric Finishing

The principals of the sublimation transfer printing process are identical to paper printing technology, and gravure printing is one of the main technologies used today. The basic principles of gravure printing are similar to engraved copper roller printing, so the initial step is to engrave the metal pattern cylinders. In modern printing operations, the surface of the metal cylinder is engraved by an automatic engraving machine equipped with diamond heads for etching the metal surface. The engraving machines are controlled by a computer system to ensure the accuracy of the engraving processes.

The printing unit consists of the pattern cylinders, color furnishing cylinders, and doctor blades. In the printing operation, each cylinder catches disperse dye inks from each color of the furnishing cylinders and all the excess inks on the surface are removed (scraped) by the doctor blades so the inks are only retained in the etched pattern areas. After pressure is applied to the pattern cylinders and papers, the inks are printed onto the papers. With current technology, printing speeds of over 100 m/min can be achieved and the systems can accommodate designs with as many as 10 colors. Disperse dye inks are required because of the high speed of operation (so that the paper dries quickly) and to prevent puckering and disintegration of the mark offs. Disperse inks for this process are typically formulated with volatile solvents such as petroleum distillates.

Gravure printing is a high volume printing system, mainly because printing volumes need to be balanced against the high set-up costs of the cylinders and paper. Nonetheless, there are numerous advantages for this technology, including:

• very fine detail and tonal shading effects in designs can be achieved,
• print mistakes can be found on paper prior to printing on cloth,
• can be used to print stretchy and unstable fabrics,
• it is a dry process so does not require steaming or washing, and equipment costs are low.

Gravure Printing Press

Gravure Printing Press Description:
1. Gravure printing press’s suitable for BOPP, PET, PVC, PE and combined film and paper with the same properties, its printing speed is 50m/min, while the mechanical speed is 60/min.
2. The main transmission system adopts speed-adjusting motor to control the speed.
3. Gravure printing presses can realize printing in single-side, dual-side, muti-colors, and has function of meter counting.
4. The material receiving , the traction of material receiving and feeding adopt moment motor, while material feeding adopts magnetic powder braker.
5. The ink circulates automatically with the ink pump.
6. The dry system adopts dual oven tunnel. The up-and down oven of each printing unit adopts centrifugal blower to bring in the air. Gravure printing press is of cast iron chassis and to dry the materials 50 per minute. The temperature of oven can be adjusted and controlled automatically.
7. The position of ink scraper can be adjusted freely up and down, pre and post. And it adopts horizontal movement repeatedly.
8. The material receiving and material feeding device adopt reversal dual station to realize feeding and receiving materials without stopping the machine.
9. The rubber roller adopts manual pressure.
10. Printing cylinder correcting adopts differential transmission device. The printing cylinder can be adjusted in 360 degrees vertically freely. Its horizontal adjustment scope is 30mm.

Gravure Printer

Gravure printer is to print BOPP, PET, CPP, PVCD, al-plated film, the compound film and paper with the same properties .

Gravure Printer Main Function:
1. Tension control with 7 sets of AC motors.
2. Machine is logically controlled and protected by PLC, and the value is set by touch screen.
3. Shaftless pneumatic cone installed plate, cylinder precise gear box driver device.
4. Heavy doctor blade device with double pneumatic cylinders.
5. Unwinder/rewinder tower, automatic splicing in the high speed print.
6. Gravure printer pre-driver automatic vertical color control and video display.
7. Heat source: electricity, vapour ect.