The global market for sanitary napkins is undergoing a major shift toward “cotton-soft,” “textile-feel,” and “lingerie-like” solutions. To meet these consumer expectations, manufacturers are replacing traditional spunbond topsheets with high-loft air-through bonded (ATB) nonwovens.
These substrates offer significantly improved comfort but introduce a critical process issue: a massive, progressive fiber build-up on the plates of inline flexo printing units.
Traditional cleaning methods such as manual washing and web cleaners cannot address the root cause, while the NIC™ (non-stop in-line cleaner), with its contactless hydraulic cleaning technology, provides the definitive technical solution to maintain OEE and print quality on modern converting lines for hygiene products.
1. The physics of printing on high-loft substrates
To fully understand the complexity of the issue, it is essential to examine the physical interaction between high-loft substrates and the printing plate.
1.1 The substrate shift
Traditional nonwovens (spunbond) are calendered, compressed and stabilized into a compact two-dimensional surface.
High-loft materials, however, use through-air bonding to preserve fiber verticality (loft) and provide softness. The result is a surface made of millions of upright fibers, weakly bonded and mechanically unstable.
1.2 The “velcro effect”
Flexo printing relies on controlled pressure and ink transfer. When the inked plate meets a high-loft substrate, three key phenomena occur:
- Contact: the plate wets the substrate surface.
- Extraction: as the cylinder rotates, the adhesive force of the ink exceeds the weak fiber bond, pulling fibers out of the material.
- Build-up: the extracted fibers accumulate on the plate surface.
1.3 Formation of the “cement”
Unlike loose surface dust, the extracted fibers combine with the water-based ink resin and dry under hot-air dryers. This creates a compound that hardens like cement within the plate’s screen structure. Such build-up produces defects—hickeys, bridging, and loss of fine detail—compromising delicate designs typical of “lingerie-look” products.
2. Why traditional solutions fail?
Converters in the hygiene sector typically rely on two established solutions, neither of which can effectively address the true nature of the problem.
A. Web cleaners (contact or vacuum)
• Function: remove surface dust and loose particles before printing.
• Limitation: high-loft fibers are not loose dust; they remain anchored to the web until the viscous ink on the plate extracts them during the printing nip. No web cleaner can prevent this mechanism.
B. Manual cleaning / stop-and-wash
• Function: stop the line to manually clean the plates.
• Limitations:
• Operational losses: hygiene lines often run above 800 units per minute; stopping every two hours dramatically reduces productivity.
• Safety risk: manual interaction with doctor blades and nips carries significant hazards.
• Poor repeatability: manual cleaning applies friction directly to the plate and can damage the photopolymer relief, critical for delicate pastel patterns.
3. The solution: NIC™ (non-stop in-line cleaner)
NIC™ introduces a radical shift in plate-cleaning methodology: from friction-based removal to pure hydraulic action. It is the only system capable of removing fibers embedded in the plate relief during production, with zero physical contact.
3.1 The technology: 100% contactless cleaning
NIC™ uses a mobile cleaning head mounted on a linear rail that travels along the full length of the plate cylinder.
• Step 1: Water jet: a series of micro-nozzles delivers a high-speed mixture of air and water (or solvent). The kinetic energy breaks down the hardened fiber/ink compound.
• Step 2: Vacuum extraction: a cyclone vacuum system immediately removes liquid, ink residues, and fibers.
• Step 3: Aerodynamic drying: an integrated air knife fully dries the plate before it meets the anilox.
Crucial advantage: cleaning takes place between the printing nip and the inking station, preventing residual fibers from being re-inked and re-bonded onto the plate.
3.2 Asset protection (zero plate wear)
NIC™ operates with no contact on the plate, eliminating abrasion risk.
• Benefit: printing on high-loft materials requires soft plates with extremely fine screens, essential for lace and pastel patterns. Contact-based cleaners quickly wear these details.
• NIC™ result: fluid- and air-based cleaning preserves the photopolymer relief, significantly extending plate life.
3.3 Sustainability and consumables
In facilities with multiple production lines, consumable management is a significant operational factor.
• Liquid consumption: in cleaning mode, the NIC™ requires only one liter of liquid every twenty-four hours.
• Waste reduction: it eliminates the need for cleaning wipes, generating only a small amount of liquid waste managed by the cyclone system.
4. Operational impact
Based on data from converters in the tissue and hygiene sectors, the adoption of NIC™ delivers transformative economic results.
Typical case study: hygiene line (24/7 operation)
• Without NIC™: manual cleaning stops of fifteen minutes every 2–4 hours due to fiber build-up.
• Result: ~1,320 hours of downtime per year.
• With NIC™: fully automatic cleaning cycles during production.
• Result: 80% reduction in cleaning-related downtime.
5. Integration and retrofit capability
• Compact footprint: NIC™ cleaning head is compact.
• Modular design: the control cabinet (PLC, vacuum, filter) can be installed remotely, with only the linear rail remaining inside the print deck.
• Universal compatibility: designed to integrate with any flexo machine, it is the ideal solution for standardizing facilities with mixed equipment fleets.
The growing use of “super soft” high-loft nonwovens is not a temporary trend but the new standard for premium hygiene products. Fiber extraction and resulting plate contamination are no longer anomalies, they are intrinsic effects of the printing process.
Traditional solutions such as web cleaners and manual cleaning address the symptoms, not the root cause.
NIC™ directly tackles the physics of the phenomenon: fiber extraction is inevitable. With continuous, contactless cleaning, it enables high-speed printing on even the softest, most fiber-rich materials while maintaining consistent quality and process stability.
Written by Lorenzo A. | Team Giugni®
