The stack-type flexo printing machine is one of the three main types of flexo printing machines. A stack-type flexo printing machine features multiple printing units arranged vertically on a single machine frame, with each printing unit operating independently. The structure is compact, and setup and maintenance are relatively straightforward. Each printing unit includes an anilox roller, flexographic plate roller, pressure roller, and drying system. It can control the ink volume and registration independently. It can be optionally equipped with 2 to 8 color groups, which is very suitable for flexible packaging web printing.
Compared with a central drum flexo printing machine, where all printing units share a large central impression cylinder that holds the substrate in place during printing, double-sided printing typically requires an additional turn bar device or a separate printing pass to print the reverse side.
Features of the stack-type flexo printing machine:
1. Structural layout: Each printing color group is stacked independently on top and bottom. Each color group has its own independent impression and drying unit, and the material path is suspended. Compared to the central drum flexo printing machine, the equipment cost is lower and installation and maintenance are simpler.
2. Double-sided printing capability: A stack-type flexo printing machine can print on both sides of the substrate in a single pass when configured with printing units for both sides.
3. Wide substrate adaptability: Can print on various materials such as kraft paper, laminated paper, various packaging bags, plastic films, non-woven fabrics, etc., suitable for paper-plastic type soft packaging orders.
4. Production and order adaptation: Easy to change plates and adjust machines, flexible proofing, suitable for small and medium batch, multi-variety packaging printing orders. One-pass winding completes multi-color printing, effectively reducing material loss and improving production efficiency.
Unwinding Unit
Rewinding Unit
I. Advantages of double-sided printing
1. Double-sided printing in a single pass, significantly improving production efficiency. The substrate is only processed once, and the Double-Sided Printing graphics are printed simultaneously. The processes of rewinding, re-pressing, and re-setting the plate are omitted, shortening the production cycle, and it is very suitable for double-sided graphic orders for packaging bags, paper bags, woven bags, non-woven fabrics, etc.
2. Reduces Front-to-Back Registration Errors: Printing both sides in a single pass can reduce registration errors associated with rewinding and reloading the substrate between separate printing runs.
3. Lower labor and energy costs. No need for re-loading, re-adjusting the machine, reducing the repetitive operations of operators for resetting plates and rewinding; reducing one-time drying, equipment start-stop, saving electricity and ink consumption. The cost advantage is more obvious in small-batch, multi-variety orders.
4. Flexible color group configuration, Double-Sided Printing colors can be freely allocated. Modular independent color groups can be allocated with N colors on the front and M colors on the back (for example, 4 colors on the front + 3 colors on the back). There is no need for the same color number for the entire machine, suitable for various orders: some have multi-color printing on the front and only single-color text / warning signs on the back, suitable for soft packaging, paper bags, fertilizer woven bags, etc. with differentiated requirements.
5. Lower equipment investment and space requirements. Compared to purchasing two printing machines for double-sided printing or adding a post-stage flipping and rewinding solution to a CI machine, the entire machine occupies less space, the equipment investment threshold is lower, and it is suitable for small printing factories.
6. Easy changeover, suitable for multi-category, small-batch orders. The stack flexo printing machine itself has simple changeover and debugging, the double-sided mode and single-sided mode can be quickly switched. The same machine can handle single-sided orders and switch to one-pass double-sided printing, with higher equipment utilization and suitable for multi-variety, short-order markets.
II. How the stack machine achieves double-sided printing
A stack-type flexo printing machine can achieve double-sided printing in a single pass by arranging the printing units to print on both sides of the substrate.
In a double-sided printing configuration, some printing units print the front side while others print the back side, allowing both sides to be printed in a single pass.
III. Key Supporting Systems of the Stack-type Flexo Printing Machine
1. Inter-unit drying: Hot-air drying or UV curing, depending on the ink system and machine configuration, helps prevent smudging and ink transfer.
2. EPC Web Guiding: full correction to prevent deviation after flipping;
3.Servo drive + forward and reverse registration detection: real-time compensation for the registration errors of the Double-Sided Printing graphics; older gear machines have larger deviation in double-sided registration, while servo models have significantly improved accuracy;
4. Tension segmented control: separate tension control for the unwinding section, front printing section, flipping section, and back printing section to avoid film stretching and deformation.
Heating and Drying Unit
Unwinding Unit
IV. Precautions for Double-Sided Printing / Process Limitations
1. Material restrictions for the stack flexo printing machine: high stretchable film materials pose risks, and thick materials / hard rolls have limited applicability.
2. Hard drying requirements: The printing process must ensure that the ink on the front side is completely dry before proceeding; otherwise, it may result in ink smudging on the back side or ink transfer.
3. Registration characteristics: there are differences in registration between servo and gear models for double-sided printing.
4. Production speed impact: compared to single-sided printing, the operating speed of the double-sided mode usually needs to be appropriately reduced.
5.setup waste during color or substrate changes:Double-sided printing incurs higher wear and tear when changing colors and substrates.
IV. Precautions for Double-Sided Printing / Process Limitations
1. Material restrictions for the stack flexo printing machine: high stretchable film materials pose risks, and thick materials / hard rolls have limited applicability.
2. Hard drying requirements: The printing process must ensure that the ink on the front side is completely dry before proceeding; otherwise, it may result in ink smudging on the back side or ink transfer.
3. Registration characteristics: there are differences in registration between servo and gear models for double-sided printing.
4. Production speed impact: compared to single-sided printing, the operating speed of the double-sided mode usually needs to be appropriately reduced.
5.setup waste during color or substrate changes:Double-sided printing incurs higher wear and tear when changing colors and substrates.
V. Sample Printing Capabilities of the Stack-Type Flexo Printing Machine
Our stack flexo printing machine handles a wide range of common packaging materials for diverse print jobs.
● Film types: PE, LDPE,HDPE,BOPP, PET etc.
● Paper types: paper, paper bags, paper cups, paper boxes, etc.
● Others: non-woven fabric, aluminum foil composite film.
VI. Sample Types of Printing Processes
1.Single-Sided Printing Samples: 2, 4, 6, or 8-color printing, including solid backgrounds, lines, halftone patterns, text, and logos.
2.Double-Sided Printing Samples: Front-and-back printing with different color combinations, such as 4+2 or 4+4 colors, suitable for paper bags, packaging films, and nonwoven materials.
3.Ink Types: Water-based inks for paper and flexible packaging, as well as solvent-based or UV inks, depending on the machine configuration.
4.Substrate Samples: Printing on kraft paper, coated paper, PE, BOPP, PET films, and nonwoven fabrics, depending on machine specifications.
5.Print Quality Samples: Solid color coverage, fine text, line patterns, and halftone graphics to evaluate print clarity, color consistency, and registration accuracy.
VII. Summary
A stack type flexo printing machine offers a flexible solution for printing on a wide range of roll materials, including paper, plastic films, and nonwoven fabrics. Its independently arranged printing units support different color configurations and can be set up for single-sided or double-sided printing. With suitable machine configurations, it can print both sides of the substrate in a single pass, helping improve production efficiency and reduce material waste. It is particularly suitable for flexible packaging manufacturers handling diverse products and small- to medium-batch orders.
1.How do I pick a suitable stack-type flexo printing machine to match my production needs?
You need to look at your substrate material, maximum web width, number of print colors, target running speed and typical order size. These points will guide you to lock in a proper machine setup.
2.Is customisation available for stack flexo printing machine to fit different packaging jobs?
Absolutely. We can adjust print width, colour groups, drying units and add supporting accessories to fit your unique production demands.
3.What separates servo-driven stack-type flexo printing machine from gear-driven versions?
Servo-driven presses deliver more flexible print control and finer tuning. Gear-driven units work well for standard printing runs. Your target print quality, running speed and budget will decide which fits better.
4.What points should I check when buying a stack flexo press for a brand-new production line?
Check its compatibility with your current machines, workshop layout, substrate specs, drying needs and room to expand output later. Don’t overlook installation, operator training and after-sale technical support either.
5.What factors affect the price of a flexo printing machine?
Cost varies based on print width, colour count, drive type, running speed and extra add-ons. Send us details including your substrate, required width, colour quantity, target speed and configuration needs for an exact quote.
Post time: Oct-19-2026