Some Thoughts on the Quality Control Measures of Calendar Printing

Some Thoughts on the Quality Control Measures of Calendar Printing

In order to print high-quality color Calendars, it is necessary to realize effective control of image and text overprinting, ink transfer, gradation and other aspects according to the conditions of paper, printing method and printing medium, so as to achieve the printing of color Calendars in overprinting, gradation, color, etc. Quality control metrics for restoration, ink color uniformity, etc.

Ink balance control

To correctly control the ink balance in actual production, the following points need to be paid attention to.

(1) It is necessary to correctly grasp the relationship between the amount of water, the amount of ink and printing. (2) To master the principle of less water and thick ink. Less water is based on the premise that the blank part of the layout is not sticky and dirty; thick ink means that the amount of ink is appropriately increased on the basis of less water. (3) Correctly control the fountain solution. Experience shows that the surface tension of the fountain solution should be slightly larger than that of the ink. It is generally believed that the surface tension of the fountain solution is about 4.0×10-2 to 5.0×10-2N/m, which is conducive to achieving ink balance. (4) Excessive emulsification of ink affects the balance of ink and water. In actual production, emulsification of ink is inevitable under the extrusion of rollers, water rollers and ink rollers. However, excessive emulsification of ink will bring a series of problems to printing.

Overprint Quality Control

Achieving good and accurate multi-color overprinting during the printing process is very important for printing good prints. The types of inaccurate overprinting of color Calendars include irregular deviation of the printed image, partial deviation of the printed image, and regular deviation of the printed image position in the same direction. For various problems, they should be treated differently in production. The reasons for the paper itself, the accuracy of the printing machine, the printing pressure, the pre-press plate making process, including the operator's skills and the equipment maintenance status of the printing machine may all affect the accuracy of overprinting. factor. Our company's Roland machine UNISET60 often has an axial registration deviation in one of the two PS plates on the same cylinder of the M plate cylinder. In order to improve the registration accuracy, the machine personnel use scissors to modify the position of the PS plate positioning holes to compensate for overprinting. Error is a solution adopted after analyzing specific problems.

Color Calendar appearance quality control

To evaluate the quality of a Calendar, the first thing to do is to evaluate its aesthetic effect. This requires not only ink color, layout, title density, pictures, registration, but also the appearance of the Calendar.

(1) The layout of the Calendar is clean and tidy, free from pressure, rubbing, scratches, edge printing, etc., no damage, wrinkles, folded corners, and no obvious through-printing. The pinhole is less than 5mm, and there is no gap.

(2) The layout is flat and there are no missing prints. No partial ink color unevenness or partial ghosting, no partial text fading, no ink streaks or white streaks (water roll printing).

(3) The center of the plate is centered on the left and right, and the deviation is less than the allowable error of 2mm. The head of the sky is slightly larger than the foot of the ground (1-2mm). The center of the front and back layout is aligned, and the upper and lower and left and right errors are less than 2mm.

(4) The folding is accurate and neat, the drift error is less than 2mm for one fold, and less than 4mm for two folds, and the cutting is neat and has no burrs.

(5) Except for the specified color control points (bars) and the necessary bending standard lines, there should be no imposition marks such as crosshairs and CMYK versions on the layout.

Printing equipment maintenance

The quality of color Calendars puts forward high requirements on the maintenance of printing machines. The maintenance of the printing press is divided into a three-level maintenance system. Here we talk about the work focus of machine personnel around the three-level maintenance system.

1. Daily maintenance of the machine

(1) The blanket, water roller and ink roller should be cleaned. (2) Measure the pH value, concentration (conductivity) and water temperature of the fountain solution in the water tank before printing; after printing, clean the water tank and the filter screen of the water tank. (3) Check whether each gear box is short of oil before printing, check whether the wallboard is leaking oil during printing, check the oil pipe and oil nozzle after printing and refuel in time. During the printing process, inspect the air pump and clean the motor filter. (4) Clean the paper roller, olive roller, conveyor belt, paper guide roller and pinch roller after printing. Prevent wrinkles, smudges, and inaccurate overprinting in printing. (5) Fill in the shift record. Follow up and respond to the problems explained by the previous class, and record the operation of the machine and new problems in the current class.

2. Machine weekly maintenance

(1) Clean the water bucket and water pan, check the surface quality of the water roller, and adjust the pressure of the water roller. (2) Check the working status of the cutter, cutting strip, gripper, folding knife and bite knife, and adjust and replace the wearing parts in time. (3) Clean the folding knife roller, the bite roller and the roller guard to prevent the product from sticking and dirty during the printing process. (4) Review the oil pump, oil circuit and other lubrication systems. (5) There are plans to remove the ink roller, check the rubber roller bearing, check the surface quality of the ink roller, and adjust the pressure of the rubber roller. (6) Fill in the raw material replacement record.

3. Monthly maintenance of the machine

(1) Cooperate with electromechanical maintenance to check the copper sleeve of the roller connecting rod to maintain the multi-color registration accuracy. (2) Replace the blankets in a planned way, and use 2 sets of blankets alternately. (3) Clean the water supply pipes of the water tank in a planned way. (4) Clean the gearbox in a planned way and replace the lubricating oil. Clean the filter screen and oil circuit system.

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