Thermal Transfer (or TTO) works by melting solid ink from a roll of film onto the surface of the to-be-printed packaging material (substrate). First, the film containing the ink is rolled out inside of the printer and across the substrate so that they make contact. Next, a thermal printhead is transported across the back of the film. This melts and releases the ink pixel by pixel (300 DPI) from the film and onto the substrate. The sequence of heating of the pixels can be digitally controlled making variable prints possible.
Because the printhead and film are in contact with the substrate during printing, we refer to this as contact coding. The printer is in fact installed directly onto the packaging or production line by a support bracket. If the substrate is in movement while printing we refer to this as continuous operations. In this case, the printhead in the printer remains static while the substrate moves to create the print. In intermittent printing, this is the opposite and the printer transports the printhead across the substrate while this component remains static.
Thermal transfer printers are mostly used in the primary segment of the packing process (at the individual product level). TTO is ideally suited for printing on non-porous packing film. A second common use of TTO is to print the variable information op pre-printed (coloured) labels. The high resolution makes it possible to create high quality graphic prints like logos, texts, symbols and bar codes.