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The Secrets of Successful Pad Printing

(February 2003) posted on Wed Mar 12, 2003

This discussion expains how you can make the most of your machine by considering all aspects of production, from climate and press location to substrate readiness and ink preparation.

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By Carol Swift, Peter Kiddell

Dust is another real pain. Cardboard from packaging, for example, releases fine fibers that can settle on components and ruin the print. Other dust sources include clothing, human skin, and debris carried in from outdoors on garments and shoes. Floors and surfaces near the machine never should be brushed to remove dust; instead, these surfaces should be wiped with a wet rag or mop, or simply vacuumed.


Contamination can come in less obvious forms, too. For example, if parts are brought into the production area from a cold, dry storage location, the warmer, more humid air in production can cause moisture to form on the part surfaces until they warm up. If the parts are immediately printed, this invisible layer of water can compromise ink adhesion. So always let parts acclimate to the production environment.


Static elimination


Static electricity can be a serious problem in pad printing, not only because of the problems it causes with ink adhesion, but because it attracts dust that can lead to additional print problems. As mentioned previously, static can occur on blank plastic parts when they are packed in plastic bags for shipping. But this isn't the only cause.


Static electricity is an inherent byproduct of the pad-printing process. It is generally caused by the compression of the silicone-rubber pad onto the plastic parts being printed. The static charge can affect ink transfer to such an extent that printing is not viable. Very low humidity levels only make the problem worse.

If static problems can't be solved with simple solutions, such as slowing the print cycle or adding antistatic additives to the ink, it may be time to consider the use of static eliminators. These devices produce ionized airflows that are directed at the part during printing and draw off static charges so that the items are receptive to the ink. Static eliminators come in a variety of shapes and sizes that support virtually any pad-printing equipment and a range of production configurations.

A final alternative for reducing static is to use printing pads that are less likely to generate the static charge in the first place. One new type of silicone-rubber pad that is emerging inhibits the generation of static electricity and even removes the need to wipe down pads with solvent during production runs.

Solvent balance in inks



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