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Options and Accessories for Productive Pad Printing

(March 2007) posted on Wed Mar 07, 2007

Examine some of the solutions on the market today.

click an image below to view slideshow

By John Kaverman

In many single- and multicolor applications, it is necessary to increase the amount of air flow over the surface of the part and/or the pad in between prints to speed drying and increase adhesion of subsequent colors. Usually, a separate, compressed-air line and regulator are necessary, as are separate inline regulators for each individual branch.

Flame-treating equipment

Certain substrates require pre-treatment to increase their wettability—or ability to accept the ink and allow it to flow. Material such as LDPE, HDPE, PET, PP, PVC, EPDM, and EVA are examples. Flame-treating equipment requires propane or natural gas, so one of those two needs to be available near the machine.

Corona/plasma treating equipment

Instead of using flame, corona and plasma treating equipment use electrical current to produce an ion-rich discharge that increases the wettability of the surface exposed. This equipment is more expensive than flame-treating equipment, but it is faster, cleaner, and doesn't require any fuel—only electricity.

Static-control equipment

Sometimes static is a problem. Packaging materials, plastics, the friction of the machine, or even low humidity can generate static. When necessary, static-control equipment like de-ionizing air nozzles and air knives can be added to the pad printer or feed systems.

Automatic pad-cleaning systems

Also known as tape-off, automatic ink-residue systems can remove debris from the pad very quickly. These systems can be add-ons to existing machines or built-in on some newer machines. In most cases, the frequency of tape-off (cleaning) is programmable. Usually the tape-off occurs after image transfer. After the pad prints and returns to the up position, a slide mechanism positions a tray of tape adhesive side-up under the pad. The pad compresses on the tray quickly, the slide moves the tray back out of the way, and the next printing cycle starts.

Ink pumps

Ink pumps are sometimes used on automated open systems. Particularly useful on vertical rotary pad printers, ink pumps automatically control ink viscosity. Usually, the ink drains from the lowest point in the ink well into a container where thinner is automatically added and mixed into the ink. The ink is then pumped back up into the inkwell.

Thinner-metering systems


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