Marking systems for direct marking are used to produce markings by mechanical forming, machining or electrochemical erosion of workpiece surfaces. The marking is always done by contact and without the use of dyes. The processes include needle marking, scribe marking, embossing, engraving and electrolytic marking. Needle and scribe marking systems as well as engraving systems enable the production of individual markings through a freely programmable marking movement. In contrast, electrolytic marking systems and embossing systems are based on prefabricated templates or stamps or type wheels and allow only limited flexibility in the marking content.
The most common functional principle is forming. In needle embossing, dot-shaped markings are impressed into the workpiece surface of the component by pressing in a hardened needle, whereby the marking is composed of a large number of individual dots. With scribe marking, on the other hand, a linear marking is created by a permanently pressed needle that is drawn over the surface of the workpiece. In stamping and embossing systems, raised numbers and letters are typically pressed into the workpiece surface by pressing, hammering or rolling, displacing the material and creating a permanent stamp impression.
In the case of engraving, the markings can be created by machining, where a rotating cutter mills out the desired marking parallel to the surface of the workpiece. In contrast, with laser engraving or electro-engraving, the material is removed by vaporising the material.
In electrolytic marking, a template is imprinted on the workpiece under the interaction of current and electrolyte. The process is based on electrochemical erosion, in which the material surface is oxidised to a depth of a few micrometres.