December 17, 2010
Why does my anilox not transfer the exact volume of ink that the manufacturer states on the roll or inspection report?
Although it is not often clearly stated, all anilox volumes are given as a theoretical volume as there are so many variables that can and will affect the final volume of ink or coating that is released from each cell. The volume that you will be given by all manufacturers is a mathematical calculation based on the cell opening, depth and base of the cell and is usually an average of a group of cells, the exact number of which depends on the method of measurement and equipment used.
Now this number will be quite accurate, but as mentioned, it is the other variables on press that really affect the final volume of ink or coating that will be transferred. For most modern ceramic anilox this can be as much as 85% or more but due to the surface energy between the anilox, metering roll, printing plate and finally the substrate the final amount will and does vary. This variance can be quite dramatic particularly when an ink metering roll is used, which can actually lead to a greater amount of ink being transferred than has been quoted due to the hydraulic forces between the anilox and metering roll and the limited ability to sheer the excess ink or coating from the surface of the anilox.
In some instances where extra coat weight or density is desirable, this can be beneficial but if you are wanting to maintain consistent densities and coat weights then a doctor blade is always going to give you more consistent results and better volume control. The actual chemistry, viscosity, temperature, substrate, plate material, press speed, and drying system also all have a bearing on how much volume can and will be transferred.
Finally, how well you keep your anilox clean will also have a dramatic affect on any anilox cell’s volume carrying capacity, which is why good house keeping and cleaning of the anilox is so vital from day one that you put it on the press. The use of the right cleaning solutions, stainless brushes (for ceramic) and cleaning systems such as ultrasonics are all essential if you want to sustain any anilox’s volume carrying capabilities. Of course if you change any of the other factors previously mentioned the volume transfer will change as well so maintaining good records and being aware of these variables is vital if you want to get the maximum ink or coating to be released from each engraved cell.No Comments