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Many pad printing machine designs exist but there are three basic configurations: the conventional open inkwell design, the rotary gravure process, and the sealed ink cup system. As with the other key elements, variations exist within each of these categories:
Open Inkwell Pad Printing Machines
Open inkwell pad printing systems are older pad printing technology that use a trough or ink well for the ink supply, located behind the printing plate. A flood bar pushes a pool of ink over the plate, and a doctor blade removes the ink from the plate surface, leaving ink on the etched artwork area ready for the pad to pick up.
The Rotary Gravure Process
Rotary gravure technology is preferred in applications that require printing in a continuous motion or printing around the complete circumference of a part. This pad printing process shares many design features with open inkwell technology in that it uses an open inkwell and doctor blade assembly. The printing plate is a cylindrical steel drum that contains the etch on its surface. The silicone transfer pad is in a circular or roll form, typically with an aluminum hub and silicone rubber perimeter.
Both drum and padroll are mounted onto shafts with the drum rotating in one direction and the transfer pad rotating in the opposite direction. As the two items make contact, the transfer padroll pulls the image out of the etch and then deposits it onto the part.
Sealed Ink Cup Pad Printing Machines
Sealed ink cup systems are the latest in pad printing technology. Sealed ink cup systems use a sealed container or ink cup, which then acts as the ink supply, flood bar and doctor blade all in one. A ceramic ring with a highly polished working edge provides the seal against the printing plate.
Learn about the pad printing pads that are used in both types of pad printing machines.
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