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Many printing machines have ink throwing phenomenon. However, the operators only care about the ink throwing and do not throw it on the product. Where is the ink thrown out?
Anilox roller scraping
The ink accumulated for a long time will form strips and hard blocks. When it reaches a certain thickness, the ink residue will fall directly onto the anilox roller! When the hard block is relatively large, it will be stuck between the anilox roller and the rubber roller or scraper. Constant friction will scratch the anilox roller for a long time, resulting in small linear color difference when printing products. Be sure to open all the machine covers for cleaning during maintenance.
Anilox roller blocked
When the printing press is finished, the ink on the baffle will flow along the baffle to the anilox roller if it is not dry. At this time, the equipment has stopped, and the ink will dry up on the anilox roller after a period of time. Due to the relatively high viscosity of the ink flowing down the baffle, the blocking of the anilox roller will be more serious. When large color blocks are accumulated for printing for a long time, it will be found that there is always color difference or white exposure.
In addition, poor printing will also occur due to ink problems
1、 Poor hue (unable to lead out standard hue)
Causes: low ink viscosity, ink separation, sedimentation, low ink loading, poor ink transfer
Solution: add the original ink, constantly stir the ink bucket, increase the amount of ink, and check the roller and printing plate
2、 Poor viscosity (unable to reach the specified viscosity)
Reason: the rolling of ink and wash, foaming, solvent evaporation and excessive dilution of water.
Solution: measure after ink circulation, add defoamer, special solvent, raw ink and thickener
3、 Poor drying of printed matter (too slow drying)
Reasons: Ink viscosity is too high, ink piling, poor ink drying, poor ink absorption, paper splashing
Solution: dilute the ink, adjust the plate pressure and height difference, add quick drying agent, and replace with paper with good ink absorption
4、 Pile ink
Causes: uneven plate thickness, excessive plate pressure, high ink viscosity and excessive ink amount
Solution: correct the height difference of the layout, reduce the plate pressure, add diluent and reduce the amount of ink
5、 Produce burrs
Reasons: the viscosity of ink is too high, the drying speed of ink is too fast, the plate pressure is too large, and paper powder is mixed
Solution: reduce ink viscosity, add slow drying agent, adjust drying speed, reduce plate pressure, and filter ink with filter screen
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