Introduction
Post-printing and pre-printing of corrugated cardboard are two different printing processes:
Post-printing is printing directly on the surface paper of corrugated paper (usually three or five layers).
Flexographic printing, offset printing or computer inkjet printing can be used.
Flexographic printing is one of the common post-printing methods. It has the advantages of high speed, high quality and high efficiency, and can use water-based ink, which meets environmental protection requirements.
The advantage of post-printing is that it can be produced on-line, which improves production efficiency. At the same time, it has low requirements for printing base materials and relatively low equipment prices.
Pre-printing refers to a new process technology that first uses a wide-width pre-printing machine to print and rewind the surface paper of the corrugated cardboard in multiple colors, and then bonds it with single-sided corrugated paper on the corrugated cardboard production line to form a patterned cardboard.
Pre-printing can use a flexographic pre-printing machine or a gravure pre-printing machine. The flexographic pre-printing machine has the characteristics of high production efficiency and can achieve large-format multi-color color printing.
The advantages of pre-printing include high overprinting accuracy, full printing ink color, bright and firm colors, high production efficiency, and suitable for mass production.
How Pre-Printing Works
The first step is to turn on the machine. The system has a one-button power on and off setting. You only need to connect the power, turn on the power button, turn on the nozzle, clean and check the nozzle.
After the pre-printing machine is turned on, the marking and coding needs can be completed under the originally set parameters. For some special requirements, such as synchronization, meter counting, piece counting, etc., the pre-printing machine can also set relevant parameters to complete these tasks by itself.
When setting, you can see the changes in the settings on the screen. This is the "what you see is what you get" function of the screen. According to the parameters on the screen, you can easily adjust the content of the logo.
After the printing work is completed, for the pre-printing machine that is resting for a short time, it is necessary to add a cleaning agent to clear some ink residues before performing the relevant actions of shutting down. For machines that are resting for a long time, a more thorough cleaning is required to facilitate smooth use next time.
Advantages of Pre-Printing
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It can achieve higher printing quality and wider adaptability. Pre-printing uses gravure or flexographic printing machines to print on smooth paper surfaces. Compared with post-printing using printing slotting machines to print on uneven cardboard surfaces, it can perform exquisite color printing with richer layers and brighter colors, and the printing quality is more stable and reliable.
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It can make corrugated cardboard have higher strength. Since the pre-printing method does not require the cardboard to be pressed after it is formed, it can avoid corrugation deformation and weakening of cardboard strength. When using a corrugated cardboard printing slotting machine for post-printing, each color printing will cause more or less deformation of the corrugated cardboard, and the more colors there are, the greater the deformation effect on the corrugated cardboard.
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High production efficiency, easy production management, and low scrap rate
Limitations of Pre-Printing
Higher cost: Advanced equipment and materials are required, which leads to an increase in production costs.
High technical requirements: Preprinting technology has high technical requirements for operators and requires specialized operation and maintenance personnel, which also increases the operating costs of enterprises.
What is Post-Printing?
Post-printing refers to printing directly onto the already corrugated cardboard sheet or box after the fluting and lamination process is complete.
How Post-Printing Works
Die cutting: Use a die to cut the printed corrugated cardboard into a predetermined shape.
Creasing: Press fold lines on the cardboard for subsequent folding.
Slotting: Make V-shaped or U-shaped notches on the cardboard to facilitate the folding of the carton.
Nail or glue: Fix the cut, creasing, and slotted cardboard into a carton with nails or glue.
Bundling: Bundle the cartons for easy transportation and storage.
Finished product stacking: Stack the bundled cartons neatly together to complete the final packaging.
Advantages of Post-Printing
Save labor costs.
Reduce printing costs of consumables.
Meet the requirements of environmentally friendly printing.
The corrugated carton printer prints computer files directly on paper, starting from one sheet, without plate making, plate imposition, color calibration, immediate access, instant error correction, variable data, and on-demand printing.
The full digitalization of the corrugated carton printer can provide a more flexible printing method, that is, printing and modifying, modifying and printing, realizing zero inventory in the true sense. This flexible and fast printing method enhances the customer’s advantage in a competitive environment where every second counts.
Limitations of Post-Printing
Traditional corrugated box printing processes are usually suitable for printing cartons with low printing quality requirements and simple graphics. For high-end cartons that require high-precision, multi-level printing, this process may not meet the requirements.
During the printing process, the carton may be deformed, especially when there are more printing colors, this effect will be more significant. This may cause the compressive strength of the carton to decrease, affecting its stability during transportation and storage.
The adaptability of corrugated box printing machines is relatively narrow. For different types of cartons and different printing requirements, it may be necessary to adjust or replace the equipment, which increases the complexity and cost of production.
Comparison: Pre-Printing vs. Post-Printing
Pre-printing: refers to printing the roll paper before the corrugated board is produced, collecting the paper into rolls after printing, and then sending the printed paper to the corrugated paper production machine for laminating and forming. The advantage of this method is that the corrugated paper is not affected by the printing pressure, so the appearance of the corrugated paper box after forming is more ideal.
Post-printing: usually refers to the printing or other processing steps after the corrugated paper box is formed. For example, conventional offset printing of corrugated paper boxes uses indirect printing, that is, printing the paper box first and then laminating it on the corrugated paper.
Choosing the Right Printing Method
When it comes to determining the best printing method for a job, the number of copies, carton size and print quality requirements are the main determining factors. Flexo post-printing can meet most requirements and achieve the greatest improvement in print quality.
Future Trends in Corrugated Cardboard Printing
It will have a more intelligent operating system that can automatically adjust parameters according to different printing needs to achieve efficient production.
Summary
Choosing pre-print or post-print depends on budget, order size, design complexity and turnaround time.
Pre-print is ideal for high-quality graphics and mass production.
Post-print offers businesses a cost-effective, flexible and customizable solution.