Industry News

After years of competition in the flexible packaging market, what is the difference between flexographic and gravure printing in terms of product quality? Gravure printing machines and flexo printing machines are the main printing machines for flexible packaging. In everyone's impression, gravure printing has good quality but is polluting.

Gravure Printing Machine

Flexographic printing is environmentally friendly, but some packaging cannot achieve the desired printing quality.

Flexo Printing Machines

Is this true? How do the relevant data compare?

Flexographic printing is a direct rotary printing method that uses a flexible raised image plate. The plate is attached to a plate cylinder of variable length. The plate is inked by a metal roller with engraved inking holes (anilox roller), which is inked by another roller or doctor blade.

Anilox Roller

Flexographic printing can transfer liquid or grease inks to a variety of substrates. It is not only suitable for non-woven materials, printing shopping bags, storage bags, etc. ; it is also suitable for roll paper materials, printing coffee cups, takeaway paper bowls, takeaway paper bags, fruit cartons, hamburger boxes, etc. In addition, flexo printing machines are also suitable for plastic film materials, printing soft packaging of potato chips, diapers and tissues, plastic bags, etc. Although it is essentially still a letterpress printing, it is listed as a separate printing method because the plate ink and the printing process are different from traditional letterpress printing.

Application

So what are the differences in product quality between flexo and gravure printing machines? The main indicators of printing quality are as follows: screen ruling, ink loading amount, overprint accuracy, printing quality control factors, etc.

1. Screen Ruling

Screen printing can reach 70 lines per centimeter and 175 lines per inch; while flexographic printing can generally reach 48 lines per centimeter and 120 lines per inch; high-quality layered flexographic printing can reach 52-60 lines per centimeter and 133-150 lines per inch.

Screen Ruling

2. Ink Loading Amount

During normal printing, the ink application of gravure flexo offset printing is 4-8 grams/㎡ for gravure, 3-5 grams/㎡ and 0.8-2 grams/㎡ for flexographic printing, and 1-2 grams/㎡ for UV offset printing. The average ink application ratios of silk screen printing, flexographic printing and offset printing are 400%, 267% and 100%. From this, it can be seen that gravure printing can achieve the greatest brightness.

Ink Loading Amount

3. Registration accuracy

Central impression flexo printing machine can achieve similar registration accuracy as unit gravure presses, but unit flexo presses generally cannot achieve the above accuracy.

Central Impression Flexo Printing Machine

4. Quality control factors

Compared with gravure printing, flexo printing has more factors affecting its quality, such as color separation, duplication, plate exposure, printing installation, installing the plate on the drum, tape thickness and quality, etc.

Plate Cylinder

When laser imaging is used for plate making, a clearer image can be obtained, 1% of the dots and 60 lines per centimeter and 150 lines per inch can be achieved; while laser engraving can be made using rotary plate making equipment, and sleeve-type flexographic plates are also conducive to quality control.