Flexo Printing Press FAQ: Color Stations, Registration, Plates

How many color stations do I need on a flexo press?

Count the colors in your typical artwork, then add one or two stations for flexibility. Most box and bag jobs need four to six colors, so a six-color press covers standard process printing plus a spot color or coating. Choose the number of stations based on your real order mix — buying extra unused stations adds cost and lengthens every setup, while too few forces you to run jobs twice or compromise on design.

How do I keep print registration accurate on a flexo press?

Registration starts before printing: keep the board or paper flat and consistent in thickness, and use a press with servo-driven, independently adjustable print stations. Set the plate mounting accurately with a plate mounter and check the tension of the web or the feed of sheets, because any stretch or slip shifts colors. Modern presses with automatic register control and camera inspection catch drift during the run, but operators still need to verify registration at startup and after every plate change.

What printing plates should I use?

Choose photopolymer plates for most jobs because they give clean, consistent dots and long life, and match the plate durometer to the substrate — softer plates for rough corrugated board to avoid halo and washboard effect, harder plates for smooth paper and film. Rubber plates are cheaper for very simple, long-running solids. Keep plate thickness tolerances tight across a set, because uneven plates are a common cause of uneven print pressure and color.

Why is my flexo print showing banding, ghosting, or uneven color?

These defects usually trace back to three causes: worn or incorrectly metered anilox rolls, wrong doctor blade pressure, or uneven plate-to-substrate pressure. Check the anilox roll for wear and clogged cells, verify the ink viscosity and pH are within range, and confirm the impression settings are even across the print width. Ghosting is often a plate or anilox cell-volume pattern repeating, so clean the anilox regularly and store plates flat away from heat and light.

How fast can a flexo press print and how does speed affect quality?

Modern flexo presses run at high linear speeds on paper and film, and sheet-fed presses for corrugated run at high sheet counts per hour, but every material has a speed where print quality starts to drop. Watch for ink misting, dot gain, and register drift as you push speed, especially on absorbent corrugated board. Set your operating speed from the quality your customers require and your drying capacity, not from the machine's maximum rating.