The basic principle of laser marking is that a high energy continuous laser beam is generated by a laser generator. The focused laser acts on the substrate material, making the surface material melt instantaneously, or even vaporize. By controlling the path of the laser on the material surface, the required graphic marks are formed. Three methods of laser marking are described below.
1. Dot matrix laser marking
One or several small lasers are used to emit light pulses at the same time. After passing through the reflector and the focusing lens, one or more laser pulses will ablate small pits with uniform shape on the workpiece surface (the diameter of the pits is generally $15pm). The characters and patterns marked by the laser are composed of multiple small round pits. Generally, the maximum number of vertical strokes is seven points, and the maximum number of horizontal strokes is five points, forming a 7x5 array.
2. Mask laser marking
The mask marking structure is composed of TEACO laser and mask. The mask is made of sheet metal with high temperature resistance. Characters, barcodes or patterns are dug out of the mask by hollowing out, mechanical engraving or photographic etching. The laser beam is collimated and shines parallel light on the mask. The laser beam penetrates from the hollowed gap of the mask to form the shape of character barcodes or patterns. After passing through the convergence lens, the reduced figure according to the required scale is reflected on the surface of the workpiece and is ablated into marks.
3. Galvanometer laser marking
The structure of galvanometer laser marking is mainly composed of Q-switched YAG laser, high-speed galvanometer system, computer control system, etc. The computer system is used to control the galvanometer system to scan along the XY axis and mark figures, characters and graphics on a certain surface.
There are two forms of focusing: one is to focus first and then shine on the workpiece through the galvanometer system.
The other is that the beam passes through the galvanometer system first, then passes through the focusing mirror, and then hits the workpiece. This method can mark the area of 50mm x 50mm or 100mm x 100mm. The area of the mark can be adjusted at will, and various complex characters, patterns and images can be marked.
