Printing on corrugated to many customers has become as important an element in package design as protection. There are a variety of different ways to apply graphics to corrugated board. The main three are flexography, lithography, and digital printing.
Flexible printing plates are mounted to a cylinder and pick up a fast drying water based ink from an anilox cylinder that is metered by a rubber roll or doctor blade system. Sheets are fed through the cylinders and graphics are transferred to the corrugated board. This is also known as direct print. There are a number of machinery alternatives available to converters and every converter is equipped a little differently.
Flexography is also used in preprint applications where the printing is applied to the outside liner prior to being converted into a corrugated sheet. This process offers printing advantages but requires certain levels of volume before it can be considered an option.
Litho quality graphics can be incorporated into corrugated packaging in 2 ways, either through single-face laminating or labeling the combined board. Both result in high quality graphics with bright colors and sharp resolution.
Single face laminating
A printed “top sheet” can be laminated directly to the medium as the outside liner. The printed top sheet covers the entire sheet and is then ready to be converted.
Labeling combined board
Also known as litho labeling, a printed sheet or label is laminated to corrugated board. The label can be full sized or “spot”. Full sized labels are laminated prior to converting whereas spot labeling can be done after the box has been converted.
Digital printing is the most recently developed printing technology. Graphics from a digital computer file are transmitted directly to a printer that plots the graphics onto the corrugated board. This eliminates the need for printing plates. However because it is a time consuming process digital printing is used primarily for short runs of high graphics. As speeds pick up this method of printing is sure to gain popularity.