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FLEXOGRAPHIC PRINTING

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PDF FILE - FLEXOGRAPHIC PRINTING - BOX LEARNING EXERCISE
 

Flexographic printing (also known as Flexo), results in a clearly printed image,with sharp colour quality. This makes the flexo printing process popular with the packaging industry and many others. Improvements to this process are relatively recent and is due to print plates being made to greater precision, through the introduction of computer control and 3D systems. The flexographic process is the modern, technological version, of the letter press.

The manufacture of the ‘flexible’ print plates is costly, making this printing process economiwith large continuous print runs only. Flexographic printing is usually combined with web-fed systems (the material to be printed on, is supplied in large rolls). The inks are in the form of gels (not liquids) and therefore, fast drying.

The process is ideal for the printing of packaging, wallpaper, calendars, books, laminated tetra paks and food packaging. The material that receives the print, known as the substrate, can be paper, card, polymers, textiles and even metallised films (polymers coated with a thin layer of metal).

 
 
 
 
HOW IT WORKS
 
The print plates are carefully and accurately arranged on the print cylinder. The gap between the impression roll and the print cylinder is set precisely, according to the thickness of the web-fed printing material (substrate). The ink reservoir is filled to a level, that allows the anilox roll to rotate through it. The flexographic printing machine is then set to run. The web-fed printing substrate, continually feeds around the impression roll, coming in contact with the print plates, leaving the pattern on the substrate. The print plates are re-inked by the anilox roll, which in turn rotates through the ink reservoir. The anilox roller is designed to hold a particular thickness of ink. This type of roller is only found in flexographic printers.
 
SAMPLE PRODUCTS - FLEXOGRAPHIC PRINTING
 
 
 
 
ADVANTAGES AND DISADVANTAGES OF FLEXOGRAPHIC PRINTING
 

Advantages:

Only economic on long print runs.
Fast and simple, with minimal breakdowns, ensuring continuous print runs. Low maintenance costs.
Can be combined with web-fed systems (rolls of substrate), which is much cheaper and faster, than using a sheet fed system.
Often combined with die cutting and laminating, as one machine.
Fast drying inks (even bio-inks) can be used. Some inks can even infuse wax coatings as found with tetra paks, OR dry as a separate coat, on the surface of tetra paks.

Disadvantages:

Modern print plates suitable for flexographic printing, are extremely expensive and are not economic for short print runs.
Changing from one print run, to a completely different print run, is time consuming and therefore costly.
The printing machinery can only be operated by trained, semi skilled staff.
Interruptions to a print run can be costly.

 
 
 
RUBBER FLEXOGRAPHIC PRINT PLATE
 
Flexible polymer / rubber print plate is hardwearing. The image areas (areas to be printed) are raised above the other areas, as shown below.
 
 
The anilox roller is only found in flexographic printers. It collects a precise thickness / coating of ink, from the ink reservoir and passes this on to the print plate.
 
 
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