I have etched thin steel plates that are etched to about 30 microns and am using a sealed cup pad printer.
I run and print 5-10 parts that look great and then the image starts becoming washed out looking with voids. If I leave the machine for a few minutes the print looks good again and then goes back to missing pieces syndrome. I am new to pad printing and would appreciate some advice.
This is indicative of an ink viscosity problem. If your ink is drying too fast, the pad won’t be able to pick the entire image up from the etched area of the cliché. In that case, you’d add a little thinner to the ink – or retarder if the ink is already quite thin. Another option would be to remove any pauses that may be set in the printer controls to slow the drying process a little. If, however, your ink is too thin it will not completely release from the pad. Then, when the pad goes to pick up the image for the next print cycle it will deposit some of the previous image back into the cliché. To remedy this, either slow the print cycle down – putting a pause on the print side of the cycle (and maybe even one on the pickup side) or try directing some hot air at the pad after it has picked up the image to help the ink dry a little more before printing. If this doesn’t help you may want to start with a fresh batch of ink that you know has been set to the correct viscosity.
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