Operation process of Rotogravure printing machine

Lucy Wang

5月 31, 2022

KETE GROUP LIMITED is the professional supplier pouch production line machines in China . In the process of printing with rotogravure printing, accidents caused by improper operation often occur. What are the operation procedures and matters needing attention of gravure printing machine? Here are some notice for your reference .

KTMS-B

Rotogravure Printing Machine

Workable material : plastic film roll, paper rol ,etc.
Speed :80-120m/min
Printing unit : 1-10 color ( can be customzied )
Shaft-less Pneumatic Type Printing Cylinder Installation Design.
Auto Ink Recycle System.
With Computer Auto Color Register System and Web Video Inspection.
Optional: 3 / 5 / 7 Drive Tension Control System

Printing process when printing plastic film - Rotogravure printing machine

Feeding → tension control → printing 1 color → drying → overprint second color → drying → overprint third color → drying → overprint fourth color → drying → rewinding.

Rotogravure printing machine operation rules

1. Prepare before printing -rotogravure printing machine

Check whether there is dust, garbage and sundries irrelevant to printing around the printing machine, and check whether ventilation and exhaust facilities are in good condition.

2 . Check whether the raw and auxiliary materials are ready and whether they meet the printing requirements. The plastic film for printing need meets the following requirements:

Smooth surface, no obvious hard block, yellow black spots, holes and excessive wrinkles;

The average thickness error of the film to be printed should be less than 10% (at 1m printing width). The formula for calculating the average thickness error will be found in the requirements for dry composite substrate film. Under printing pressure, the elongation of the printed film should be within 1%; The surface tension of substrate film should be ≥40 dyn/cm; The affinity between the substrate and the printing ink is known in advance. For the film that is easy to dissolve and swell with the solvent in the printing ink, the printing speed and the concentration of the printing ink can be greater. When printing the coating of the coating film, we should know how the adhesion of the coating resin to the ink.

3. Check the quality of the plate roll. Note that the latter group of color plate roller should be slightly larger than the previous group of color. For example, the circumference of the second plate roller should be 1% more than the circumference of the first plate roller, at least slightly larger or slightly equal, not less than the first plate. Otherwise, can not accurately overprint. Check the pattern and color code of the reel.

4. Check whether all parts of the printing machine have card material problems, including transfer printing, feeding, drying, inking, traction and winding, lubrication part is filled with lubricating oil, oil is smooth. Are the instruments in good condition? If there is an automatic ink viscosity controller on the equipment, the ink viscosity should be adjusted to the preset value of 14~18s, and poured into the mixed solvent.

5. Mix ink, choose the same primary color ink with the proofing color standard.

2. Install printing cylinders -rotogravure printing machine

When installing the plate, pay attention to the left and right sides of the plate. Do not twist the cone too tightly, so as not to burst the copper plate roller loose, printing will “escape”. Install plate cylinder according to printing color sequence. The printing color sequence is gold and silver ink → black ink → original green → original yellow → original red → white ink. When printing, it is the opposite: white ink → magenta ink → yellow ink → green ink → black ink → gold and silver ink.

3. The scraping blade-rotogravure printing machine

Scraper generally uses thin steel sheet, thickness between 0.15~0.55mm. Scraping knife with printing roller contact point tangent Angle between 15°~45°, less than 15°, the ink is not easy to scrape; Greater than 45°, the damage to the plate and scraper is relatively heavy, easy to scratch the plate chrome layer. Scraper pressure is not too large, too large, easy to damage the plate; Is too small. Not easy to scrape ink. When the scraper is used old, it can be used with 280~400 mesh oil stone, evenly stained with oil grinding from left to right, or with more than 800 mesh metallographic sand paper stained with oil to remove the scraper together with the knife holder and then clip it on the fixture evenly grinding, to prevent the scraper from hurting people’s fingers.

Ink scraper and hard blade lining plate lap, placed in the middle of the upper and lower splint, and bolted. In practice, bolts should be tightened symmetrically from the middle to the left and right ends to prevent blade bending. Ink scraper lengthening hard knife lining length of 10~20mm, lengthening too long, ink scraper soft not easy to scratch; Too short, increase rigidity, scratches too large, easy to damage the scraper and plate. The thickness of hard knife lining blade is best adjusted at 0.8~1.8mm.

4 . Start printing -rotogravure printing machine

Gravure rotary machines usually use a stepless variable speed system to control printing efficiency. In order to better synchronize the operation of each color printing unit, a main motor and a CVT are used to drive the whole printing system through a long rotating shaft. Start the ink pump and check whether the ink pump reverses. After the clutch separation of all kinds of printing plates, open the main motor, check the change of transmission speed, and then open the drying equipment and blower, close the clutch at low speed, and color matching. With the first color as the standard, open the point switch for the first second, third and fourth vertical color calibration; Then, still use the first color as the standard for the fourth color horizontal color calibration second, third, four-color alignment, using the hand wheel to adjust the horizontal chroma alignment.

Vertical and horizontal color alignment improves printing efficiency. Without fully automatic computer direct plate making equipment, the printing efficiency of both satellite rotary machines and combination rotary machines cannot exceed 40m/min. If more than 40m/min, the human eye can not track observation, usually adjust to 25 to 30m/min. The actual operator should pay close attention to the color condition and adjust manually at any time. If a computer-based automatic registration device is available, the actual operation mode should be set at self-registration time. At this time the computer can track itself, if there is a deviation, will send a correction signal, so that the version of the roll or material movement, re-alignment.

Tension control is different for different printing materials. For BOPP films, tension control is best set at 5~8kgf (49~ 78.4n) per meter width. The printing tension of biaxial stretch nylon film is controlled between 78.4N and 98N, while that of biaxial stretch PET film is controlled between 98-117.6N. If the width is less than 1 meter, simply multiply the width by a scale of 1 meter, such as 0.7 meters. Then multiply the above tension by 0.7.

5. After finishing printing order - rotogravure printing machine

After the printing task is finished, turn off the main motor and turn off the printing material feeding. Lift the embossing roller, separate the plate with a scraper, turn off the ink pump, pour out the remaining printing ink, rinse the plate surface until there is no residual ink, take out the printing material, turn off the drying equipment, electric heating, clean the floor. When the plate is no longer in use, the plate is removed, the two ends stand up and placed on a special plate bracket. If not used for a long time, please pack and store in the warehouse. A set of printing rollers should be placed together to avoid interference. Labels should be attached to the outside and indicate how many copies have been printed so they can be used at any time.

We are listening your ideas to satisfy with your customized requirement by integrating all resources and gathering all the experiences we have.