Structural variations on the surface of metallic products at laser marking

There are many various methods for marking application. For example, labels which are glued on package or directly on products, can be manufactured by printing. The labels which have the form of carrier are often molten to mark plastic products [1, 2]. However, such methods are not reliable, because applied marking is rubbing and damaging during product operation and can be replaced easily. Therefore, use of direct marking methods is required, when information is located just on the surface of finished product. Embossing and stamping can be mentioned as such direct methods, but they are just out-of-date. Electrochemical marking is also considered as direct method, but the most demanded and up-to-date technique is now various engraving, e. g. laser engraving [3, 4]. Efficiency of laser engraving use is determined by its workability, by high marking speed of products, by contactless operation, by stability and reliability of image, by suitability of apprehension and by possibility of control for legality of products using created electronic data bases [5, 6]. Action of laser emission on variation of the state of marking product is the main mechanism of laser marking. When laser emission effects on different materials (both metallic and non-metallic), local heating appears; partial melting and evaporation of material from the surface contact point [7]. If we move laser beam along the sample surface, we get any visible image presented by signs, pictures, letters and figures [8, 9]. This research used QR codes as the image applied during marking; they are widely used for marking the finished products. Structural variations on the surface of metallic products at laser marking