Laser Settings for Optimal Code Readability
The goal when laser marking a 2D code is simple: maximum contrast between the marked cells and the background, with clean cell edges and no distortion. Here’s how to achieve it.
Key Parameters
| Parameter | Impact on Code Quality | Recommendation |
|---|---|---|
| Power | Too low = insufficient contrast; too high = cell spreading, thermal distortion | Start at 50–70% and adjust for contrast |
| Speed | Too slow = excessive heat, cell distortion; too fast = incomplete marks | 300–600 mm/s typical for 2D codes |
| Frequency | Affects mark darkness and heat input; higher freq = darker but more heat | 20–50 kHz for metals |
| Hatch spacing | Must be smaller than cell size for complete fill; too tight = heat buildup | 0.01–0.03mm (adjust based on cell size) |
| Focus | Slightly defocused marks can improve contrast on some materials | Test both in-focus and slightly defocused |
| Passes | Single pass preferred; multiple passes increase heat and distortion risk | 1 pass; 2 only if contrast is insufficient |
Cell Size (Module Size) Guidelines
The size of each cell in your DataMatrix or QR code must be large enough for the laser to create clean, distinct marks. The minimum cell size depends on your laser’s spot size:
Rule of thumb: Cell size ≥ 3× laser spot size
| Laser Spot Size | Minimum Cell Size | Minimum Code Size (10×10 DataMatrix) |
|---|---|---|
| 20 µm | 60 µm (0.06mm) | 0.6mm × 0.6mm |
| 50 µm | 150 µm (0.15mm) | 1.5mm × 1.5mm |
| 100 µm | 300 µm (0.30mm) | 3.0mm × 3.0mm |
For most industrial applications, a cell size of 0.15–0.30mm (150–300 µm) provides the best balance of readability and space efficiency.
Contrast Optimization by Material
| Material | Marking Method | Expected Contrast | Tips |
|---|---|---|---|
| Stainless steel | Annealing | High (dark on bright) | Best method for code readability on SS |
| Aluminum | Etching | Moderate (light gray on silver) | Increase power for deeper contrast |
| Anodized aluminum | Color removal | Very high (silver on black/color) | Excellent code readability |
| Carbon steel | Annealing/etching | Moderate-High | Clean surface first for best results |
| Black plastic (ABS/PC) | Foaming | High (light on dark) | UV laser preferred for detail |
| Light plastic | Carbonization | High (dark on light) | Control heat to prevent melting |
The #1 readability tip: On stainless steel, use annealing rather than engraving. Annealed marks produce sharper cell boundaries because there’s no material removal — the cells are defined by color change rather than depth, which scanners read more reliably.
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