Flexographic Plate Elongation & Repeat Gear Calculator
When flexible photopolymer printing plates are wrapped around a cylindrical print cylinder, the outer image face elongates in the printing direction while the polyester backing maintains fixed length. Prepress vector artwork must be reduced (distorted) in the cylinder travel direction by a precise percentage calculated from the cylinder repeat and plate K-factor.
In Adobe Illustrator or Esko ArtPro, apply non-uniform scaling exclusively along the vertical web direction: set Vertical Scale to the exact Distortion % shown above while keeping Horizontal Scale at exactly 100.0%. Ensure all color junctions have a 0.25pt–0.50pt vector spread/choke trap to prevent white register flash during high-speed press runs.
Standard Flexo Plate K-Factor Formulas
The mathematical elongation constant K is defined by K = 2π × (Tp - F), where Tp is total photopolymer plate thickness and F is floor thickness. The required prepress reproduction factor is: