Flexography
A high-speed rotary printing process utilizing flexible relief plates. The unquestioned standard for global packaging.
The Mechanics of Flexo
Flexography is essentially a modernized version of letterpress. It uses a flexible photopolymer plate wrapped around a cylinder. Unlike offset, the image area is physically raised above the non-image area (relief printing).
The Anilox Roll System
The defining feature of a flexo press is the anilox roll. This is a steel or aluminum cylinder engraved with millions of microscopic microscopic cells. The anilox roll picks up ink, a doctor blade scrapes off the excess, and the remaining ink in the cells is transferred to the raised areas of the flexo plate.
| Anilox Cell Count (LPI) | Cell Volume (BCM) | Best For |
|---|---|---|
| 200 - 300 | 8.0 - 12.0 | Heavy solids, corrugated board |
| 400 - 600 | 4.0 - 6.0 | Line work, large type |
| 800 - 1200+ | 1.0 - 3.0 | High-end process color, flexible packaging |
Design Constraint: Minimum Dot
Unlike offset, flexo plates cannot hold a 1% or 2% halftone dot. The physical pressure will cause these tiny dots to snap off or print too heavily. Minimum printable dots are typically 3-5%, meaning smooth gradients fading to absolute zero (0%) will have a visible "hard edge" or "break" where the dots end.
Process Strengths
- ✓ Prints on non-porous films (plastics, metallic foil)
- ✓ Very high speeds (up to 2000 fpm)
- ✓ In-line die-cutting and finishing
- ✗ Lower resolution than offset
- ✗ Gradients fading to 0% are difficult
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