Roll-to-Roll Rotary Die-Cutting & FPC CAM Prepress Guide

1. The Cylinder Wrap Distortion Effect

When a flat chemical-etched or CNC-milled flexible magnetic die is wrapped around a cylindrical magnetic toolholder, the outer cutting blades are positioned at a larger radial circumference than the neutral axis of the steel backing plate. As a result, the distance between cutting teeth elongates in the circumferential (web feed) direction.

2. Blade Bevel Profiles for Converting

• 60° Single Bevel (Inside or Outside): Used when tight nested spacing (< 1.5 mm) is required between adjacent parts. Reduces web jamming and slug trapping.
• 75° Center Bevel: The industry standard for kiss-cutting pressure-sensitive adhesive labels against siliconized PET or glassine release liners without cutting through the carrier.
• 90° Center Bevel: Maximum blade edge strength for cutting tough abrasive substrates, including copper-clad polyimide FPC stacks and thick foam gaskets.

3. Cavity Ejection Pin & Foam Placement

Internal waste drop slugs must be actively ejected from rotary cavities to prevent slug packing and blade tooth chipping. CAM files must include dedicated ejection foam keep-out contours with a minimum clearance of 1.2 mm from cutting edges.