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Question
#1422
Subject: How can I calculate the fluid transfer from an engraved cylinder?
How can I calculate the amount of coating, adhesive, or ink applied from an engraved cylinder?
Answers (links jump to full text of answer below)
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#1423
Author: Larry Gogolin, Gogolin & Associates
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Subject: Fluid transfer from cylinder
The simplest way to find the coverage for your cylinder is to ask the manufacturer for its conversion tables giving the coating weight for your cylinder's cell configuration and your fluid's solids concentration. They may also give you the cell volume numbers.
However, even with the theoretical values, we know that most cells do not transfer all the fluid to the web. The actual transfer is only 50% to 80% cleanout. This is true for both ceramic anilox and chrome-plated gravure rolls and is due to the differences in the fluid surface tension and the configuration and surface of the cell walls.
This means that for the best values you must run the cylinder with your fluids, on your base, and at the same blade and nip pressure, using the same backing roll, fluid temperature (viscosity), etc. You then will take that sample and run a coverage weight or thickness value in your lab. The coating weight can be obtained by taking a known area of sample and weighing both the uncoated and coated portion of the web then calculating the grams/square meter or similar value. If there is a solvent in the ink, you will need to dry the coated sample in an oven before getting a dry weight.
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#1424
Author: Eldridge M. Mount III, EMMOUNT Technologies
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Subject: Fluid transfer from cylinder
The best way is to have measured the actual consumption of the coating with a particular gravure pattern. Short of that you need to know the dry coating weight you want in the end, the % solids in your coating, and the volume of the gravure pattern you are to consider. What is missing, and you will have to assume, is the % of the gravure volume that is transferred to the film surface. You also will need the line speed and the number of cells each area of film sees in the coating region (line speed ratio of gravure speed to line speed)
By knowing the volume of the cell (from its dimensions) you can assume a percentage transfer from the film (50% to 100% as a start) and estimate the dry coating weight applied from the volume of coating deposited and the % solids of the coating solution.
This will allow you to estimate a required volume range for the gravure pattern and permit you to pick a starting point for the pattern selection or a coat weight range for a given pattern.
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