Impresión de códigos de barras en cartón corrugado: Desafíos y soluciones
Technical challenges of printing barcodes on corrugated cardboard — flute washboarding, ink spread, flexographic techniques, and verification tips.
Printing Barcodes on Corrugated Board: Challenges & Solutions
Printing barcodes directly on corrugated cardboard is one of the most challenging barcode production environments. The fluted structure, porous surface, and flexographic printing process create issues that must be addressed to produce scannable barcodes.
The Corrugated Challenge
Corrugated board consists of a fluted medium sandwiched between two flat liners. This structure creates:
- Flute washboarding: The corrugations create alternating high and low points that receive different amounts of ink
- Ink absorption: The porous liner absorbs ink, causing bars to spread wider than printed (ink gain)
- Surface irregularity: The fluted structure creates an uneven printing surface
Flexographic Printing
Most corrugated barcodes are printed using flexography (flexo), a process using flexible polymer printing plates:
- Ink is transferred from an anilox roller to the printing plate
- The plate presses against the corrugated board
- Ink transfers to the liner surface
- The result varies depending on flute alignment and pressure
Bar Width Reduction (BWR)
To compensate for ink spread (gain), barcode artwork must be adjusted:
- Bars are reduced in width by a predetermined amount
- The reduction compensates for expected ink gain during printing
- Typical BWR: 0.05-0.15mm depending on board grade and ink
Without BWR, bars print wider than intended, reducing the space widths below decode thresholds.
ITF-14: Designed for Corrugated
ITF-14 was specifically designed for corrugated printing:
- Wide bars (minimum X = 0.635mm) tolerate more ink spread
- Bearer bars prevent edge-to-edge ink migration
- Only 14 numeric digits reduces symbol complexity
- Interleaved encoding provides natural error resilience
Pre-Print vs Post-Print
| Method | Description | Quality | Cost |
|---|---|---|---|
| Pre-print | Barcode printed on liner before corrugating | Higher | Higher |
| Post-print (flexo) | Barcode printed on finished box | Lower | Lower |
| Post-print (label) | Barcode label applied to box | Highest | Moderate |
Pre-printing on flat liner stock avoids the washboarding effect, producing higher-quality barcodes. Many retailers now accept labels applied to corrugated as a cost-effective quality improvement.
Quality Guidelines
| Parameter | Corrugated Guideline |
|---|---|
| X dimension | Minimum 0.635mm (ITF-14), 0.495mm (gs1-128-term/" class="glossary-term-link" data-term="GS1-128" data-definition="Code 128 subset with GS1 Application Identifiers for supply chains." data-category="1D Linear Symbologies">GS1-128) |
| Bar height | Minimum 32mm |
| Bearer bar width | 4.8mm for frame bearer (ITF-14) |
| Ink | High-density, fast-drying flexo ink |
| Quiet zones | 10X minimum, measure from bearer bar edge |
| Verification | Grade C minimum, test on production boards |
Troubleshooting
| Issue | Cause | Solution |
|---|---|---|
| Bars too wide | Ink gain exceeds BWR | Increase BWR value |
| Bars uneven | Flute washboarding | Align barcode parallel to flutes, or use labels |
| Low contrast | Kraft board absorbs ink | Use pre-printed white patch under barcode |
| Inconsistent grade | Pressure variation | Check print impression settings |