Selecting Inks and Plates for Your Flexo Printing Machine

I’ve worked with corrugated carton and packaging converters for decades, specifying flexo inks, plates, and press configurations for high-speed production and specialty runs. Selecting the right combination for your flexo printing machine determines color quality, press uptime, waste, and regulatory compliance. In this guide I explain how to evaluate substrates, match ink chemistry to process, choose plates and anilox cell volumes, and integrate changes into your workflow so you hit quality targets without unnecessary cost.

Understanding Your Substrates and Production Goals

Know the substrate: corrugated board, liner, or film?

The first technical decision is the substrate. Corrugated carton stocks (single-face, single-wall, test liner, kraft liner) absorb ink and show surface texture differently from coated papers or films. I always start by testing the actual corrugated board you’ll run on the press—not a lab sample—because flute type, liner basis weight and surface sizing change ink laydown and dot gain significantly. For non-porous films (BOPP, PE, PVC), solvent or UV-curable inks are often required to achieve adhesion and fast solvent/IR/UV curing.

Define production priorities: speed, durability, or visual impact?

Your priorities—maximum throughput, long-term outdoor durability, or high-fidelity graphics—drive ink and plate choices. For example, high-speed case-making lines may favor fast-drying water-based or UV inks coupled with harder plates to resist wear. Retail-grade packaging focused on color precision may need softer photopolymer plates and tighter anilox control to reduce haloing and improve wet-trapping.

Set measurable targets (density, dot gain, adhesion)

Before changing inks or plates, set numeric targets: target solid density (e.g., 1.55 for PANTONE solids), max allowable dot gain (e.g., 25–30% for corrugated), and adhesion criteria (cross-hatch or rub tests). Standards like ISO 2846 (color and transparency requirements for printing inks) provide reference points for ink behavior: ISO 2846.

Choosing the Right Flexographic Inks

Ink chemistry overview: water-based, solvent-based, and UV

Flexo inks fall into three main chemistries with distinct behavior:

• Water-based (aqueous): Lower VOCs, good for porous substrates like corrugated; require heat-assisted drying or IR/air systems.
• Solvent-based: Fast dry and good adhesion to many substrates, but higher VOCs and stricter environmental controls.
• UV-curable: Instant cure via UV lamps, excellent adhesion to non-porous substrates, high gloss, and low VOCs—but require proper lamp and conveyor setup and can be costlier.

Authoritative industry guidance on flexography and process selection can be found at the Flexographic Technical Association (FTA): flexography.org, which discusses process choices and best practices.

Comparing ink types: key metrics and when to choose which

These benchmarks are indicative; real figures depend on press model, substrate, and formulation. For industry process references see the FTA and ISO documentation: FTA, Flexography overview (Wikipedia).

Case study (anonymized)

I advised a mid-size converter transitioning from solvent to UV inks for a high-gloss folding carton SKU. We performed a pilot: switched to UV-curable inks, upgraded to LED UV modules, tightened anilox cell selection and changed to medium-hard plates. Results: 12% reduction in make-ready time, 20% lower overall ink consumption per job, and elimination of solvent VOC controls—payback of the UV conversion in 18 months. This real-world outcome underlines the importance of integrated assessment (ink chemistry + dryer + plates).

Keshenglong & Shinko: Manufacturer Spotlight and Why This Matters

Company overview and capabilities

Keshenglong, founded in 1995 and merged with Japan Shinko in 2017, is a leading Chinese manufacturer specializing in corrugated carton printing and packaging machinery. Their product range includes flexo printers, computerized high-speed flexo slotting die-cutting machines (1–6 color), computerized high-speed flexo case makers, 6+1 high-precision precision printing slotting die-cutting machines, top & bottom printing slotting die-cutting machines, jumbo-size flexo printing slotting die-cutting machines, and integrated stacker solutions. Shinko continues as the R&D center and production base with another factory in Guangzhou. Main parts are imported from Japan and assembly is supervised by experienced Japanese technicians to ensure quality parity with Japanese standards.

Competitive advantages and technical strengths

What sets Keshenglong & Shinko apart in my experience is their combined technical lineage and export footprint. Key points I emphasize to clients:

• Japanese-guided R&D and assembly practices yield consistent machine tolerances and long-term reliability.
• Wide product portfolio—machines tailored for corrugated flexo printing slotting die-cutting and end-of-line automation—support integrated workflow upgrades.
• Export experience to over 70 countries indicates mature after-sales and parts supply networks—critical when validating new ink/plate combinations across multiple sites.

How their machines support ink & plate optimization

Keshenglong flexo printers and slotting die-cutting machines are engineered to allow precise anilox control, modular drying/UV options, and robust registration systems—features I consider essential for implementing new ink chemistries or plate types. If you plan to test water-based versus UV on the same line, machines that accept modular dryers and have strong web-control systems save validation time and reduce risk.

Implementation Checklist and Troubleshooting

Pre-press checklist

• Confirm substrate batch and request manufacturer specification sheet.
• Define target print metrics: density, dot gain, adhesion test method.
• Confirm plate exposure and durometer per press run length.
• Specify anilox cell volume for each color and solid requirements.

Pressroom setup and trial steps

• Mount plates using calibrated equipment; validate registration points.
• Conduct a pilot run at 50% speed to validate drying/curing and ink transfer.
• Measure spectral densities and adjust ink viscosity/tack as needed.
• Document make-ready time, spoilage, and ink consumption for ROI modeling.

Common problems and fixes

• Ghosting/halo: reduce anilox volume or increase plate durometer; check impression pressure.
• Poor adhesion on films: switch to solvent or UV inks and run adhesion tests (cross-hatch, tape).
• Insufficient cure with UV: measure lamp intensity and ensure correct conveyor speed; consider LED vs mercury lamp differences.

FAQ

1. How do I choose between water-based and UV inks for corrugated boxes?

Choose water-based if you prioritize low VOC and your corrugated substrate is porous and your press has adequate hot-air drying. Choose UV if you need instant cure, higher gloss, or must print on non-porous films. Run small trials to confirm adhesion and cost impact.

2. What anilox cell volume should I use for fine halftones on corrugated?

Fine halftones generally require moderate anilox volumes; a common starting point is mid-range volumes appropriate to your plate relief—trial three anilox rolls around the expected volume and measure dot gain. Consult your anilox supplier and the FTA guidance for more precise calibration: FTA.

3. How often should I replace flexo plates on continuous runs?

Plate life varies by durometer, ink type, and abrasive load. For heavy-duty case-making expect tens of thousands of linear meters; for high-graphic retail runs expect shorter plate life. Monitor visual wear and run length data and rotate plates proactively to avoid quality drift.

4. Are there regulatory considerations when switching ink chemistries?

Yes. Solvent inks have VOC regulations and may require capture/abatement systems. Food-contact packaging inks must meet regional regulations (EU, FDA). Always consult ink supplier declarations and regulatory documentation and perform migration testing if necessary.

5. Can I use digital flexo plates with my existing press?

Often yes—digital photopolymer plates are designed to be compatible with standard flexo presses, but check plate thickness, mounting requirements, and exposure characteristics. Proper mounting and plate mounting equipment are critical to exploit the higher detail of digital plates.

6. How do I validate color consistency across multiple production sites?

Use standardized color measurement (spectrophotometers), set target Lab values, and implement ICC profiles where appropriate. Document ink batch numbers, plate production IDs, and anilox roll IDs to ensure repeatability. Consider sending master calibration proofs between sites.

Contact & Next Steps

If you’d like help evaluating inks, plates, or a retrofit for your flexo printing machine, I can assist with hands-on trials, ROI analysis, and vendor coordination. For machine procurement, Keshenglong & Shinko offer a range of corrugated carton flexo printing machines and integrated solutions. Visit https://www.shinkomachinery.com/ or email sales at kl@keshenglong.com.cn to discuss equipment tailored to your ink and plate strategy.

References: Flexography overview (Wikipedia): https://en.wikipedia.org/wiki/Flexography; Flexographic Technical Association: https://www.flexography.org/; ISO 2846 reference: https://www.iso.org/standard/52520.; EPA printing industry guidance: https://www.epa.gov/air-emissions-standards-printing-and-publishing/printing-industry; DuPont Cyrel: https://www.dupont.com/brands/cyrel..