Flexography is a printing process that uses a flexible relief plate to print on a large variety of substrates including paper, plastic, metallic films, and even cellophane. Flexography, or flexo printing, is widely used for food packaging and printing solid color or pictures over wide areas. As with all mechanical presses, parts wear and advances in technology can leave the used flexo press behind. Because of the high cost ($250,000 to $1,000,000) of a new flexo press many printing businesses are in search of more cost effective means of upgrading their existing flexo presses. This article deals with an easy and cost efficient upgrade for a used flexographic press, the Servo 3000, made by Rotary Technologies.
In rotary printing such as with a flexo press the substrate (paper, etc.) is pulled through the press. The force used is referred to as web tension. The web is the roll of paper, cellophane, etc. on which the press prints. Precise control of web tension is important in flexo printing as poor control results in a blurry image and may cause cuts and folds to occur in the wrong places, destroying the work. When a four color print job is being printed the colors are applied at four different stations on the press. Poor web tension makes the substrate arrive at a station at the wrong part of the print cycle and will result in a blurred and useless image. The more precise the ability of the press to control web tension the better the final product. Because the Servo 3000 reads 10,000 pulses a second its first pass printing precision is extreme.
Web registration refers to the ability to precisely control the position of the web, the substrate, in relation to the flexible printing plates and other functions of the flexo press. In the case of a servo system, such as the Servo 3000, it re-registers the web on previously printed material. It then reads registration marks to allow it to precisely control the subsequent printing process. The same servo precision that produces excellent first pass results allows a Servo 3000 assisted press to produce precise results on subsequent passes.
The Servo 3000 Flexo Press Upgrade
The Servo 3000 Digital Infeed + Re-register system made by Rotary Technologies is an easily attached and portable flexo press upgrade. This system has a specially coated, servo driven pacing roller which feeds material into the flexo press. The roller, plus gripper wheels that act as a nip, provide positive traction and prevent any slippage. Because the servo mechanism receives and acts on an encoder signal from the press it precisely follows the press and not the other way around.
Web Tension Infeed Mode
The infeed mode of the Servo 3000 feeds material into the press. Because of the servo feedback function, the material is paced into the press proportionate to press speed. At slower speeds there is more web tension and at higher speeds less web tension. The scale that the Servo 3000 uses to adjust speed and web tension has 250 micro settings. Thus the Servo 3000 allows a flexo press to print in a complete tension range from tag stocks to thin films. For the press operator this is a setting in tenths between 0.0 and 25.0. Because settings are digital they are repeatable for various materials and are not affected by temperature, run time, unwind roll diameter, or any other factor that typically affects web tension on a standard flexo press.
The Servo 3000 allows a press operator to re-register pre-printed material done on the same or another press. A print sensor reads print registration marks on the web. The Servo paces the web so that print marks are locked in register to the press. This feature allows a flexo press to be used to repeat print runs to correct mistakes (instead of losing material) and increase color capacity by making extra print runs with additional colors. It also allows the press to print multilayer labels by first printing the top layer and then re-registering the web for printing and finishing subsequent layers.
Tangible Benefits of the Servo 3000
Because of precise tracking, flexo presses fitted with the Servo 3000 will typically experience better color registration on first pass printing. Wastage is reduced on setup, during print runs, with splices, and with unanticipated starts and stops. An older flexo printer fitted with the Servo 3000 can be used to finish labels printed on a digital press. It is not necessary to buy a stand alone finishing machine that stands idle when not doing finishing work. An upgraded flexo printer can do finishing work from digital presses and do standard printing the rest of the time.
Servo 3000 Sizes
The easily attached Servo 3000 comes in three standard sizes. All machines are 16 inches high and 10 inches deep. The width of the Servo 3000 will vary with the size of the press. The three standard sizes are used to print web widths of 4 to 10 inches, 4 to 16 inches, and 4 to 20.5 inches. The Servo 3000 is easily attached to any flexo press. Because it can be used on any rotary press it can be moved to a different press when needed. The standard Servo 3000 sizes fit 90 % of press needs. If a company has a unique size requirement a non-standard size can be manufactured.
At a fraction of the cost of a new high end flexo printer the Servo 3000 will upgrade function of an existing press, save on material cost, and add flexibility as well as profit to press operations.