Best MOPA fiber laser settings for color marking stainless steel
Color marking on stainless relies on a thin oxide layer whose thickness sets the perceived color, so it is extremely sensitive to pulse duration, frequency, and speed. These are starting points for a 20–60 W MOPA galvo — your exact color will shift with your machine, lens, and the specific alloy. Run a parameter array (a grid sweeping speed × frequency × pulse width) and pick the squares you like.
Recommended starting-point parameters
| Pulse duration | 4–8 ns (MOPA, short pulse for color) The single most important knob for color. |
|---|---|
| Frequency | 60–200 kHz Higher frequency tends toward cooler blues/purples. |
| Speed | 200–800 mm/s |
| Power | 20–45% (avg power, not peak) |
| Line interval / hatch | 0.005–0.02 mm |
| Passes | 1 (color marking is single-pass) |
| Lens | f-163 (110×110 mm field) typical |
Dialing it in
- ›Color marking is the least repeatable process in laser work — build and save a parameter array for each alloy.
- ›Keep the part clean and the surface in focus; defocus changes the color dramatically.
- ›Ambient temperature and the specific 304 vs 316 alloy will shift colors; re-test per batch.
The material-test workflow
The fastest way to a reliable cut is not a perfect chart — it's a tight test loop that you only run once per machine/material combination, then never repeat:
- 1Start from this baseline. Load the starting-point numbers above as the center of your test.
- 2Run a small array. Cut a grid that sweeps speed (and power, if cutting) ±20% around the baseline — typically 9–16 small squares.
- 3Judge the edge. Look for dross, burn-back, kerf width, and squareness. Pick the square that meets your part's requirement, not the prettiest one.
- 4Log it once. Save the winning parameters against this exact machine + material so the next job starts from your proven number — not a generic chart.
Stop re-running the same test square
CutLog gives you a starting point calibrated to your wattage and lens, then remembers every cut you log — so your machine builds its own proven library. Free to start.
Frequently asked questions
What MOPA settings make blue on stainless steel?▾
Blue typically appears toward shorter pulse widths (around 4–8 ns) with frequency in the 60–200 kHz range and moderate speed. There is no universal blue — run a frequency × speed array on your exact machine and alloy and pick the square you want.
Why is my color different from someone else's settings?▾
Color marking depends on the precise oxide thickness, which is set by your laser's pulse shape, lens, alloy, surface finish, and even room temperature. Treat shared settings as a starting array, not a recipe.
Related settings
Last reviewed 2026-06-28. Values are conservative starting points generalized across brands and published cutting charts; always verify on your own machine.