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Question
#175
Subject: What is the cause and how do I get rid of lines in my gravure printing process?
Since last four weeks we have a problem in our gravure printing. There are lines which appear and disappear by themselves. These lines are hollow lines like in that particular area of appearance when we see through an eyeglass we find that there is no ink applied in that area. Some times these lines do not go by themselves but the moment we apply some soft ink ,which accumulates at the edges of the tray , the line disappear. Also sometimes my operaters use grease or jelly to remove these lines.
This phenomenon is only appearing with a vinyl based ink system when we use this system for PET printing.
The solvent combination used for this system is ;
TOLUENE:ETHYL ACETATE: MIBK in the ratio 1:1:1
We have not found any foreign particles in the ink.Filtering doesnot help much .
The climatic conditions are
Temp: 20-25deg.C RH : 75%
Answers (links jump to full text of answer below)
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#197
Author: Ed Gutoff,
Email: ebgutof@coe.neu.edu
Subject: You may want to consider changing your cell frequency.
You might find an improvement if you change the cell frequency
while keeping the volume factor the same. Pulkrabek and Munter, in "Knurl
Roll Design for Stable Rotogravure Coating", Chem. Eng. Science vol 38,
No. 8, pp 1309-1314 (1983), found that highest quality gravure coating is
obtained when the natural ribbing frequency is the same as the cell
frequency. Thus, changing the cell frequency, while keeping the volume
factor the same to obtain the same coverage, may possibly eliminate your
problem.
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