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Accessories for Automating Multicolor Pad Printing

(July 2008) posted on Wed Jul 16, 2008

Automation can improve the quality, consistency, and productivity with high-volume, multicolor pad-printing jobs. This article explores parts-handling devices and other accessories that can improve accuracy and efficiency in your shop.

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By Christopher Connell

Efficiencies in fixtures and feeding

Vibratory feeder bowls are popular options for feeding parts into automated systems and are especially useful for basic orientation and sorting of bulk parts prior to dropping or inserting them into an in-feed track. The constant vibration keeps the bulk parts in motion while gravity tends to orient them into a heads-or-tails position. A sensor eye detects any improperly positioned parts and signals an eject device to return them to the bowl. The remaining parts are pushed or inserted into the final feed track, upon which they are advanced individually by an indexing device to the pad-printing machine.

Using a dial indexer, also called a rotary table, can boost production of either a manual or semi-automatic pad press. With multiple positions, holding from four to 12 identical fixtures, output can be dramatically increased. Once a part is loaded into the fixture, it is indexed to the next position where various operations can be performed prior to printing, such as pretreatment and securing parts. Subsequent indexing steps take the part through printing, as well as post-print inspection, curing, and off-loading (Figure 1).

Dial indexers are the dependable workhorses of automated pad-printing systems. They offer efficient circular arrangement of components and highly repeatable accuracy. The end result is increased production within a compact area, while maintaining good registration on multicolor applications. The use of an indexer in a semiautomatic system can give your operator a time edge by allowing him or her to load up every fixture and run the machine continuously at top speed to achieve maximum output.

The linear shuttle is another parts-conveyance device that’s popular for multicolor pad printing. The shuttle advances a single fixture along a straight-line path at exactly programmed intervals, receiving a separate image or color at each position. You can typically apply up to seven colors successfully in sealed-inkcup systems using this device, depending on the size of the part and the image requirements. The benefit of using a shuttle in this way is its ability to hold tight tolerances on multicup systems with a single fixture. The disadvantage is its relatively slow speed and requirement for manual loading and unloading.


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