The Role of Raster Step in Fiber Laser Marking
The raster step, or hatch spacing, is the physical distance between adjacent paths of the laser beam. When configuring a fiber laser for stainless steel, this parameter directly controls the overlap percentage. A smaller raster step increases the overlap, keeping the laser beam focused on areas that have already absorbed thermal energy. This continuous heating promotes the growth of a uniform chromium-rich oxide film, which is essential for creating high-contrast black marks without engraving deep into the metal.
Balancing Contrast and Corrosion Resistance
An optimized raster step ensures both visual clarity and structural integrity. If the line spacing is too wide, the individual laser passes will be visible, resulting in a low-contrast gray mark. Conversely, too small of a step leads to overheating, which vaporizes the protective chromium oxide layer and initiates rapid corrosion. To achieve a high-quality, corrosion-resistant mark, operators should adhere to the following best practices:
- Keep the hatch spacing between 0.02 mm and 0.04 mm to ensure high-contrast line overlap.
- Set the laser power to a moderate level to avoid deep engraving, which degrades the metal's passive state.
- Use a multi-pass cross-hatching configuration to smooth out the surface and secure a consistent visual output from different angles.