Control systems for the production of cardboard packaging

This article is an abbreviated version of the article that was published by the journal “Printing journal PRINT +” under the authorship of our company

Ink

Each printing house has its own character and specifics. And therefore, in order to successfully pass the stage of ordering a pantone, it is necessary to transfer samples of the material to be sealed and which will be used for printing the entire circulation and specify the following parameters:

• whether this material will be covered with varnish or whitewash;
• what printing method will be used by the typography. For offset printing, for example, the type of printing equipment should be specified;
• the panton number in the panton fan or cloud required for production;
• the maximum value of delta E, which the printing house can receive in the paint from the manufacturer, as well as the maximum value of delta E, which will be recorded using a spectrophotometer on the finished package;
• the type of varnish that will cover the pantone (it can be oil, offset, glossy, matte or ultraviolet varnish). It is best if the varnish sample is also provided to the paint supplier for internal testing during pantone mixing and rolling;
• requirements for chemical, mechanical and light resistance of paint;
• a list of post-printing processes that the printed sheet will undergo (heat treatment, hot or cold foil application, etc.)

It must be said that it is much more difficult to work with modern paints than with those that were before. It's no secret that such harmful substances as chrome, lead, zinc and other heavy metals are used to make the paint we're used to. It is not the first year that global experts have been working on changing the composition of paint using more ecological variants of dyes, which involves more faded colors and the difficulty of mixing pantones. It is also necessary to take into account that in the case of using ecological or food paints, it is necessary to use varnishes from the same gentle series.

The system of control during the printing of the circulation

Printing machines equipped with automated control and measurement systems for controlling color reproduction with feedback, operating according to the same standard in inline mode, can solve a significant part of the problems of quality control of printed products, ensuring the stability of color reproduction. Their use will require large costs. However, you can choose between these costs and the costs of producing low-quality products. The spectrophotometric system, which is the basis of the aforementioned systems, compares the coordinates of the measured (i.e. at the output of the printing press) and reference (customer's pdf file) colors, displaying the comparison process on the monitor in the form of a graph. Correlation of measurement results is carried out either automatically or by the operator of the printing press.

It should be noted that the document of the future work in pdf format is transferred simultaneously to the color separation and the computer of the printing press, with the help of which the corresponding program of the color control system of the printing press performs the above operations. The use of this system in printing houses dramatically reduces the number of sheets per device, according to the experience of our printing house, from 20 to 50 sheets and allows you to keep the color within the specified parameters from the first to the last printed sheet.

In fact, if before a printer who "saw" or "felt" color was worth his weight in gold, now the art of the printer is being replaced by the term professional operator.

Control systems in the process of post-press processing

In fact, in the areas of post-press processing of the sheet, the control is carried out directly by the operator who produces the process. Such control does not require a sharp eye or special equipment. For example, in the cutting area, the operator checks the runners by simply bending them. In the event that the operator discovers his mistakes, it is much better when he indicates where and what mistakes were made. This significantly speeds up the process of checking and issuing the finished edition to the customer. It is better to send external errors to the inspection line, which will check immediately before gluing the package.

Inspection line

As I said before, there are excellent modern solutions for checking the circulation for compliance of the packaging with the layout declared by the customer. The inspection line checks the packaging for printing errors, and it monitors the SMUK parameters, delta E for Pantone. It also checks the packaging for compliance with the arrangement of foil, varnish, congres embossing, blind embossing, die-cutting and any other post-printing processes with the customer's original layout, which was previously loaded into the inspection equipment system.

Folding and gluing line of cardboard packaging

The following sensors can be installed for the control system on the gluing line, which will not slow down the equipment's operation:

• a sensor that reads the barcode on the packaging to prevent re-sorting in the circulation. This code is applied to the adhesive valve of the package during printing and is then transmitted to the gluing line system. If the code does not match the specified values, the package is discarded from the line without stopping the gluing process of the rest of the run. But at the request of the buyer of such equipment, the machine can stop, at the same time notifying about the entry of someone else's packaging into circulation;
• the sensor for the presence of glue on the glue valve is especially important for high-speed machines. For example, for a machine that operates at a speed of 4 meters per minute, it is very important to stop the process of issuing the package for acceptance by an employee in time, because at such a high speed, a person simply will not have time to conduct a visual inspection of the package;
• the glue application sensor along the specified trajectory is necessary to exclude the situation of the shift of the glue supply trajectory to the glue valve, and therefore to exclude the entry into circulation of a package glued inside or between itself.

Valeriia Grankina, CEO Slavena LLC (Ukraine, Kharkov)