What Is The Difference Between Flexo And Rotogravure?

There are essential differences between CI flexographic printing (central impression flexographic printing machine) and rotary gravure printing in terms of technical principles, process characteristics and application scenarios. The following is an in-depth comparison from six core dimensions, and combined with the latest industry trends to provide decision-making references:
I. Printing principle and structural design
1. Central impression technology of CI flexographic printing
High-precision positioning system: All printing units are arranged radially around the central impression cylinder with a diameter of 300-800mm, and the registration accuracy of ±0.05mm is achieved through a unified benchmark. For example, at a speed of 300 meters/minute, the radial runout of the central cylinder of the BOBST VISION CI model is ≤0.005mm, ensuring that the film is printed without stretching deformation.
Short ink path ink delivery system: Laser engraved ceramic anilox roller (line count 160-1200lpi) with closed double scraper, the ink transfer error is controlled within ±2%. In food packaging, a uniform ink layer of 1.5-3μm can be achieved, meeting FDA contact standards.
2. Rotogravure transfer technology
Pit ink storage and scraper control: The image part is a pit structure, and the excess ink is scraped off by the scraper after the ink is filled. For example, in the metal foil printing of the German HP gravure press, the pit depth of 30-50μm can achieve a high gloss solid effect.
Independent drive technology: The electronic shaft (ES) system is adopted to eliminate the mechanical transmission shaft, the material belt length is shortened by 30%, and the registration response time in the acceleration/deceleration stage is ≤0.2 seconds.
2. Ink system and environmental performance
1. Advantages of water-based ink for flexographic printing
Low VOC emissions: The VOC content of water-based ink is ≤10% (non-absorbent material ≤30%), which complies with the new national standard GB38507-2020. For example, DIC's Marine Flex LM-R water-based ink reduces VOC emissions by 90% compared with solvent-based gravure in Suntory label printing.
Innovation in curing technology: UV/EB dual curing technology (such as Comexi F2 model) achieves 100% curing of ink without solvent, which is suitable for anti-migration needs of food packaging.
2. Challenges of ink transformation in gravure printing
Restrictions on solvent-based inks: Traditional solvent-based inks have a VOC content of up to 80% and face regulatory pressure to eliminate them. For example, Changxing Jiangmei Packaging has reduced VOC emissions by 3.4 tons per year through the "oil-to-water" transformation.
Breakthrough in water-based ink technology: Jinpeng Printing has achieved a water-based white plate printability of 1.5 million prints in cigarette packaging printing, and a water-based metallic ink printing speed of 220 m/min, but the drying speed still needs to be optimized.
III. Printing quality and material adaptability
1. High precision and versatility of flexographic printing
Layered reproduction capability: High-quality flexographic printing can reach 60 lines/cm (150 lines/inch), and 1% dots can be clearly reproduced. For example, when the satellite CI flexo press drills an 8mm sound hole on a 12mm plywood, the volume error is ≤±0.5%.
Multi-substrate compatibility: By adjusting the central roller pressure (1-5bar), a variety of materials from 12μm film to 10mm corrugated board can be printed. In aluminum foil printing, the hybrid screening technology can achieve 0-100% gradation gradient.
2. High saturation and metallic effect of gravure
Solid printing advantage: The thickness of the gravure ink layer is 4-8g/㎡, which is 1.5 times that of flexo printing, suitable for high-gloss packaging. For example, when printing metallic ink on plastic film, the metallic gloss of gravure is 30% higher than that of flexo printing.
Hard material adaptability: In metal processing above HRC30, the carbide sawtooth life of gravure is 2 times higher than that of Forstner drill bits.
IV. Comparison of cost and efficiency
1. Short-run economy of flexo
Initial investment and maintenance: The price of satellite CI flexo press is 16-20 million yuan, 50% higher than that of gravure press, but the plate-making cost is only 10%-20% of that of gravure. For example, it takes only 0.5 hours to replace an 8-color plate in flexo printing, consuming 400 meters of film, while gravure printing takes 2 hours and consumes 800 meters.
Long-term operating cost: The power consumption of flexo printing is 40% of that of gravure printing, and the solvent consumption is reduced by 61.375kg/10,000 square meters, with an annual cost saving of more than 1 million yuan.
2. Long-run cost advantage of gravure printing
Plate-making life and reuse: The thickness of the hard chrome layer of the gravure cylinder is 0.3-0.5mm, and the life span can reach 1.5 million prints, and it can be reused after deplating. For example, when printing 5 million prints, the cost of gravure is 30% lower than that of flexo printing.
High-speed demolition capability: On 25mm thick steel plates, the hole saw cutting speed is 3 times that of flexographic printing, suitable for large-diameter hole processing such as pipeline installation.
5. Decision tree for typical application scenarios
Application scenarios CI flexo printing has significant advantages Rotogravure printing is a better scenario
Food packaging Water-based ink printing (such as fresh milk bags, takeaway boxes), in line with FDA standards High barrier packaging (such as aluminum foil bags), requires high gloss of metallic ink
Label printing Variable data printing (such as logistics labels), with digital inkjet module Medical labels (such as tamper-proof labels), require solvent-based inks with high adhesion
Industrial materials Corrugated cardboard printing (such as cartons), precise pressure control Automotive interior printing (such as dashboard films), requires wear-resistant inks
Mass production When the annual processing volume is greater than 2000 holes, the unit cost is reduced by 30% Single processing volume <100 holes, and the hole diameter is greater than 50mm
6. Technology trends and upgrade paths
1. Intelligent upgrade of flexo printing
Digital twin technology: Virtual simulation system simulates the printing process, and the waste of trial printing materials is reduced by 70%. For example, the Mark Andy P5 model predicts equipment failures through AI algorithms, and the average time between failures exceeds 1500 hours.
Hybrid printing technology: Flexo printing combined with digital inkjet, flexo printing for the first 4 solid color blocks and inkjet for the last 2 fine dots, increasing efficiency by 25%.
2. Environmentally friendly transformation of gravure printing
Optimization of water-based ink: The water-based white ink developed by Jinpeng Printing has a print durability of 2 million prints, breaking through the bottleneck of the industry. With shallow platemaking (cell depth 30μm), ink consumption is reduced by 40%.
Energy curing technology: UVLED curing module is integrated into the gravure printing machine, with a curing time of ≤0.3 seconds and energy consumption reduced by 40% compared with traditional UV lamps.
VII. Summary and suggestions
Scenarios for giving priority to CI flexo printing:
High-precision registration (such as hinge mounting holes), strict environmental protection requirements (such as food packaging) or complex materials (such as multi-layer plywood) are required.
In mass production, the balance between quality and efficiency is pursued. For example, when the annual processing volume is greater than 5,000 holes, the comprehensive cost advantage of flexo printing is prominent.
Scenarios where rotary gravure is preferred:
Large diameter holes (>50mm), hard metals or rapid demolition requirements, such as pipe installation or plasterboard opening.
Requirement for high gloss, metal effects or ultra-long printing (such as million-level labels).
Technical upgrade suggestions:
Flexo printing companies can introduce Forstner drills with internal cooling systems (such as VMD centering U drills), and use laser measurement systems to control the hole position deviation within ±0.01mm.
Gravure printing companies can use variable pitch hole saws (such as the German HP 30 series) to improve cutting efficiency by 20% by optimizing chip removal design.
By accurately matching technical characteristics and processing requirements, CI flexo printing and rotary gravure printing have shown irreplaceable advantages in their respective fields. Under the trend of green manufacturing and digital transformation, the two are not in a competitive relationship, but complementary solutions, jointly promoting the printing industry to develop towards efficiency, environmental protection and intelligence.