Rotary Printing

There are three different types of Rotary Printing

Off set Lithography
Rotogravure
Flexography


Rotary Printing: The rotary press works by passing the stock between two rotating drums. One of the drums is applied with ink and this drum will have the image over its surface ( either on a plate or the drum itseld). This surface is 'etched' with the image that is going to be printed. the second drum presses the paper against the inked drum and the image is transferred.

Offset Lithography (Litho) : Etched aluminum plates wrapped around a cylinder transfer ink to an 'offset' rubber blanket roller and the to print surface. Sheet fed or Wed fed.

This printing method the most commonly used for mass printing of printed items such as posters, packaging (paper) , fliers, etc. The printer can print any stock that will go through the machine but paper is the most common choice of stock.

The process consists of rolling etched aluminum plates ( with the design on ) There are usually four sheets with each designated clour ( C, M, Y ,K ) on them but sometimes spot/special colours are used and many print machines cane print up to 6 different colors. The design is inked onto a roller which rolls it onto a rubber roll connecting with it and then onto paper.

Sheet or web feed

Advantages are

- it produces consistent high quality images. They produce cleaner images and type as the rubber blanket conforms to the texture of the stock.
-It's quick and can do a high number of runs in a short amount of time
-its the cheapest method of printing

Disadvantages

-the image quality is sometimes not as good as the rotogravure method of printing.
-the cost of setting up the machine is quite high. So, smaller quantity of prints are printed using digital print instead.


Rotogravure (gravure) : Copper plates (with mirror image) tranfer ink directly to print surface, usually rolls.

This method is similar to offset lithography interms of it being a rotary printing method with cylinders used. The difference is that the image/design is actually etched on a copper plate and printed straight onto paper. So the image is etched as a mirror image on these plates. This method of printing is preferably used to print onto thicker stock. It uses process colour ( CMYK) in the printing process.

The plates are copper so they are more expensive but also more durable. It is commonly used for newspaper prints and other big runs.




Flexography (flexo) : A positive, mirror image rubber polymer plate. On a cylinder, transfer ink directly tp print surface. Usually roll feed.

This method is also very similar to the Litho and Gravure printing method. However it uses plastic or rubber plates on the rubber cylindars instead of a metal one. The rubber plates make the printing process more flexible in terms of the material that it is printing onto. It is commonly used to packaging material especially, plastic sheets that go around the actually packaging itself. eg, water bottles, sweet packets etc. It is also a CMYK process.