Thermal printing is a technique in which a printed image is produced on paper or foil with a heat-sensitive coating by means of the application of heat by a controlled printer head. Ink ribbons and thermal transfer films are used for this purpose. In the case of direct thermal printing, the heat from the thermal heat is applied directly to the heat-sensitive paper. This causes a chemical reaction in the special heat-sensitive layer of the laminate material.
For product labelling, a thermal printer must have certain specific capabilities. A precise print with sharp outlines is essential to get machine-readable results. Best results can be achieved with direct-thermal and thermal-transfer printers.
Weber-marking.com offers direct-thermal as well as thermal-transfer printers. Some of the thermal printers, like the Legi-Air 4000, run with both systems.
Thermal printers that have to print directly on the product packaging often use inkjet systems. The main advantage is that these systems are able to print on various surfaces like paper, cardboard packaging, synthetic materials or metal. It is especially used for pharmaceutical, cosmetic and food packaging and in the postal service. Thermal inkjet printers use ink cartridges with lots of tiny chambers that can be heated by an electric impulse.
The heat provokes the building of a small vapour bubble which pushes the ink through the nozzle. The tension of the vapour bubble, as well as the surface tension of the ink drop, cause the ink to hurl back within a fraction of a second. Precise and high quality prints of text, barcodes and graphics can be achieved. Another system of thermal printers with inkjet technology is the piezoelectric inkjet printer, or piezo-printer.
With this principle, the walls of the ink chamber are heated by an electrical pulse, so that they extend through the heat. The ink is pressed out of the nozzle and onto the object. By stopping the electric impulse, the walls return to their original position. In the chamber a vacuum is created, pulling the rest of the ink that has not been used for the print back into the cartridge. Both systems of thermal printers are offered on weber-marking.com.