Rotary screen printing – cutting costs by reusing the screen
For years, label printers have been facing growing pressure on costs and finding it harder to hold their own and stand out from the competition. Screen printing is one good way of creating higher added value through differentiation. Even with this printing method, though, it is becoming essential to continuously boost productivity. Taking an overall process view is the best way of achieving this. One part of this process that is becoming increasingly important is what happens to the screen after printing.
Costs per screen – and thus per label – can be cut significantly by cleaning screens carefully and thoroughly after printing, storing them appropriately and then using them again for repeat jobs. Substantial savings can be made if the initial costs and time involved in producing a screen can be eliminated for a repeat order. The more frequently screen printing is used and the greater the press operators' command of this process, the bigger the savings.
Reusing Gallus Screeny
The Gallus Screeny standard line, the Gallus Screeny S-Line and the Gallus Screeny Digital generation can all be reused without any problem. The number of times a screen can be reused depends to a great extent on motif, run length and handling.
Thanks to their advanced technology and enhanced stability and robustness, the Gallus Screeny S-Line and the Gallus Screeny Digital generation based on the same material are particularly suitable for reuse. The screen fabric has been further developed to facilitate cleaning by significantly reducing the risk of buckling in the event of careless handling. This ensures optimum print quality for repeat print jobs.
What is the best approach for using Gallus Screeny several times?
Step 1: After printing, allow any remaining ink to drip out of the screen cylinder.
N.B.: This should not take too long, as otherwise the ink reacts with the UV light and blocks the mesh permanently.
Step 2: To pre-clean the screen, briefly immerse it in an ethyl acetate or alcohol bath.
N.B.: Before use, it is essential to be aware of the local regulations relating to the use of chemicals and their impact on health.
Step 3: Thorough cleaning in the screen-washing unit (Gallus recommends screen-washing unit RG2.2, Gallus ID No. GL.0177400/00).
After the first washing process, rotate the screen cylinder so that the section that was on the bottom is on top and wash again (except Gallus Screeny for the Gallus R160 and Gallus R200).
If a great deal of washing is required, it is advisable to use two screen-washing units to obtain the best possible result and save on cleaning medium. The first pass (pre-washing) can then take place in one machine and the second pass in the second screen-washing unit. The clearer the cleaning medium during the final wash, the cleaner the screens will be. The cleaning medium should therefore be changed regularly and residual ink should regularly be removed from the washing units.
Our recommended cleaning medium is Dowanol DPnB from Dow Chemical (Gallus ID No. GL. 0178724/00, 25 litres) or Flexo Wash FW 86500. 40 litres of cleaning medium is needed to fill the Gallus screen-washing unit.
Step 4: Clean the screen again with ethyl acetate or alcohol.
Step 5: Store the screen cylinder in a dry location protected against light and UV radiation.
Step 6: In the event of a repeat job, take the screen out of storage ready for printing.
Gallus is happy to support its customers by recommending materials and providing training, service activities and printing assistance.