Reducing paper consumption in thermosetting web offset printing (1)

Adjusted by gray balance

A key element of the SystemBrunner system is gray balance adjustment. Overprinting the three printing primary colors of yellow, magenta and cyan in a certain proportion will give a neutral gray tone. This system can accurately record color deviations.

Rapid evaluation system

A five-star rating system informs the printer of the current production quality standards. System Brunner evaluation criteria are minimal, cyclical, commercial, rich, and best. Each grade is represented by a star—a star is the lowest standard and a five star is the highest.

Continuous detection

In addition to displaying the achieved quality level, the reached value is shown in a hexagon on the monitor of the console. This gives printers continuous information about the current print quality level.

Color ring: a closed loop

The entire measurement and analysis system is integrated into a closed loop. The gray balance can be continuously adjusted by using the thirty-six pieces of information obtained from the control bar.

This fully automated color calibration allows printers to react quickly to changes in coefficients, such as reducing or increasing ink supply before starting or during production, before increasing or decreasing ink supply can have a significant effect on print quality.

This not only means higher print quality, but it also has significant results in reducing paper waste. The use of closed loops is also good for production and startup. Automatic color approval allows the system to reach equilibrium faster.

Color calibration during production

In the production process, the color adjustment system is very effective in preventing paper waste. The system reacts before the printer finds quality changes due to changes in parameters. The system pays special attention to process influencing factors, such as temperature changes, blanket staining, and ink fluidity changes.

Dynamic ink control

It is particularly difficult to use a dot area coverage of less than 20% for the ink doctor blade to make process settings. It takes a long time for the system to reach stability and the desired quality. In order to speed up these processes, a set-up algorithm works well for less than 20% of the blades opening, and thus reacts more quickly to new values. With this new method, the ink blade initially opens beyond the nominal value, so the closure is below the nominal value and finally reaches the nominal value setting.

Since the initial ink was excessive and then decreased, the new setting worked quickly and the system quickly reached equilibrium.

Recycling of waste leads to repeated waste

In the production process, there are some typical waste causes, some of which are repeated wastes. The two main wastes are paper roll replacement and blanket cleaning.

In order to retain as much print as possible, when performing these processes, waste shunt control can be done to divert only a predetermined number of copies when the print passes a particular point.

Shunt when changing paper roll

If a roll of paper has been replaced, the shunt opening is opened only when the first waste arrives while the waste is approaching the press. Once the first good print arrives, the diverter shuts off again and the pass counter starts counting again.

Decide quality

The distance between the folder (blank fan) and the reject shunt is determined by different transmission devices. The startup program signals each transfer process so that the number of discards can be set. The system counts the number of copies between the folder and the reject shunt.

Window Technology

In order to ensure that the scrap is actually separated, the range before and after the scrap can be named "front window" and "post window".

Before and after adjustment, the printer can immediately access the appropriate button on the press to activate the switch. Waste shunts can be opened or closed on the console or hinged operation panel.

Three operating modes

Processes such as paper change processes, and waste shunting is completely automated.

In the semi-automatic mode, the diverter opens automatically after determining that the number of copies of the print has been reached. In this case, the diverter can only be closed manually on the console or on the folding operator panel; or it can be closed directly on the diverter. If in the printing process waste is generated due to a certain obstruction, a manual operation mode is generally used in this case.

Source: MAN Roland Co., Ltd.