Pad printing

Pad printing is an indirect gravure printing process, wherein the printing ink is transferred by an elastic pad made ​​of silicone rubber of the printing plate to the substrate. The pad printing process is the most important method for printing on plastic bodies, making it among others in the advertising industry is of great importance. It emerged from the Decalcierverfahren as 1968, the engraver Wilfried Philipp replaced the little stable gelatin tampons this process by those of silicone rubber.

Printing process

The image that is to be transferred is exposed to a positive film (offset film ) on a cliché. This cliché is then washed; the exposed printed image remains absorbed back on the surface of the printing plate. A distinction steel plates and plastic plates. For steel plates, the print image is etched into the steel surface. Steel plates found in recurring print images with high volumes using.

The promotional items printer uses mainly plastic plates, as it can expose these and wash yourself. Plastic plates have on the surface of a photosensitive layer on which the printed image is exposed. Expires, the mechanical process of printing, the ink with the aid of a doctor blade made ​​of metal or plastic is swept ( in previous years roller or brush) on the plate. In a backward movement a knife the color pulls off again and leaves her in the well. Then the tampon puts pressure on them to form, lifts, taking with ink again and goes to the substrate. There lowers the tampon, molds to the shape of leaves and the color ( printing quality) on the print.

The advantage of this pressure transmission is to deformability of the pad, through which the printing of curved surfaces (convex, concave, or irregular) is possible. The tampon takes account of its elasticity to the shape of the body to be printed and can transmit so ideally the image on the printing material. The printed image is transferred onto the pressure body. The ink transfer onto the printing material is due to the silicone oil in the pad at approximately 100%.

Application

Pad printing can be used due to its flexibility when printing on relatively complex shaped surfaces. Areas of application are, for example, the printing of syringes, toys, CDs, dishes, screw caps, lighters and coins. In the automotive sector, many parts are decorated in pad printing, such as the turn signals or windshield wiper lever.

In the advertising industry and in model railway this printing technique is very often used because many promotional items and rail vehicle models have no flat surface.

Machine technology

The mechanical design of the inking system distinguishes three basic types:

In some pad printing machines, the movements are pneumatically, with others, especially fast machines, electro-mechanical and CAMs. The latest generation of pad printing machines is driven by linear motors, what a programmable workflow guaranteed. About an automated part recognition variety of printed images will be issued without the need for the stereotype must be changed.

High quality machines usually have an automatic device for cleaning the tampon ( pad cleaning, residue pick-up ) and an automatic color dilution. Machines for integration into automated systems are functionally equipped with PLC controls and matching interfaces.