About Flexo Printing Process
Flexo printing machine has been used for decorating and packaging printing for long time because of its least expensive and simplest processes. It is widely used in many printing applications like printing newspapers, directories, comics, catalogs, cartons, packing materials, labels etc. The technique offers combination of features of rotogravure and letterpress printing. Flexographic printing is eco-friendly as it can be easily adopted to use water based inks reducing large amount of emission due to gravure or web printing processes. If you want to know about this simple printing technique, Let’s reveal flexo printing process in detail.
How It Works
The major plus point of the flexo printing machine is that it can be used to print on a variety of substrates including paper to other packaging materials. The sequence of flexo printing includes feeding the roll of substrate into the press, printing images as the substrate passes through print units. The four main operations of flexo printing process include –
Image preparation – The artwork or image is essential to prepare printing setup. The image can be captured from camera, scanner or computer. The image produced by camera is positioned in the printing area manually but if it is produced electronically, special software is used to assemble the image. The next step is to produce brown print for checking the accuracy and positioning of the image. In case of color images, color proof is produced to approve the color schemes.
Flexo plate preparation – The technique uses plates with raised images known as relief plates for printing. While printing, the raised image comes in contact with the substrate and gets printed on it. The plate is usually made of rubber, plastic or photopolymer and it is attached to roller for printing. There are three main processes used for plate preparation, they are –
· Photochemical – The photo polymer sheet is exposed to light placing a negative of the image. The next process is washing the unexposed areas with solvents or water to get the exact replica of the image. This method is fast and widely used for making plates.
· Photo mechanical – The metal plate is exposed through a negative and placed the exposed plate in acid bath. This engraved metal plate is used to produce mold of bake lite board. This mold is then pressed on rubber or plastic plates under controlled pressure and temperature to produce flexible printing plate with raised image.
· Laser engraving – It is also called direct digital plate making. The image is generated by computer or scanned. The computer supervised laser process etches image on printing plate.
Flexo printing – Though there are five types of flexo printing machine or presses such as newspaper unit, stack type, in-line, dedicated 4-6 color or central impression cylinder; all these presses employ plate cylinder also known as anilox roll to apply ink on plate and ink pan. The plate in turn applies ink on the substrate passing though plate and impression cylinder.
Finishing – It is the last process which may include coating, folding, cutting or binding etc. before the final product is ready for dispatch.