Contents
Most fiber laser marking guides give a table of numbers without explaining what the numbers actually control. Operators end up adjusting speed when they should be adjusting frequency, or fighting to produce a white mark when the real issue is fill direction. This guide explains the logic before the tables — so when a result doesn't match expectations, you know which parameter to change and why.
All values are reference starting points from GWEIKE production tests on W-series fiber laser systems. Surface finish, coating type, and alloy grade all shift the optimal window — test on your specific material before production.
Four Parameters That Control Every Mark
Speed (mm/s)
Controls how long the laser dwells on each point. Slower speed = more heat = darker or deeper marks. Speed is the coarse control for mark depth and darkness. Do not reduce speed to brighten a mark on plastics — increase frequency instead.
Power (%)
Expressed as a percentage of the machine's rated wattage. A 30W machine at 35% deposits more energy per pulse on the material surface than a 20W machine at the same setting — the absolute wattage is higher, so the same percentage translates to a larger heat input. For most surface marking effects, higher-wattage machines typically need lower percentages to achieve the same result, though deep engraving applications may not follow this pattern.
Frequency (kHz)
Controls pulses per second. At 20 kHz the laser fires fewer, more energetic pulses that penetrate deeper. At 250 kHz energy is spread across many shallow pulses. Frequency is the primary control for mark depth — not just speed.
Fill spacing & direction (mm)
Fill spacing sets the distance between scan lines. More importantly, fill direction is one of the most important controls for determining whether a mark appears black or white on metal — cross-hatch tends to produce white, single-direction tends to produce black. See Section 4.
Choose Your Effect First
Parameters are determined by the desired effect, not the material alone. Two operators marking the same stainless steel part use completely different parameters if one wants a black mark and the other wants white. Decide the effect, then look up the material row for that effect.
Black mark
Annealing that builds a thick, light-absorbing oxide layer. No material removed. Typical on stainless steel and coated metals. The dark color comes from oxide film thickness, not charring.
White mark
Fine cross-hatch creates a micro-rough oxide surface that scatters light. Appears bright white on dark metals. Best contrast on polished or satin-finish stainless.
Deep engraving
Material ablation rather than surface coloring. Produces a recessed mark with measurable depth. Used where marks must survive post-machining or grinding.
Brushed finish
Deliberate parallel scan lines that replicate mechanical brushing. Decorative use on panels and brand elements. Fill spacing controls the visible line density.
Color marking (SS)
Thin-film interference in the oxide layer produces color without paint. Different colors require specific parameter combinations plus a small defocus. See Section 7.
Surface mark (plastics / coatings)
Light surface treatment that changes appearance without penetrating to the substrate. Used on anodized aluminium, painted surfaces, and PCB solder mask.
10W vs 20W vs 30W — Which to Use When
The three power levels are not simply "more is better." They suit different production patterns with different strengths.
- Best for: Material development, small batches, color marking on SS
- Parameter style: Wide ranges — the operator finds the specific point that suits each material
- Color marking: The power level with the most consistent color marking data in our tests (Section 7) — higher-wattage machines can also produce color marks with tighter calibration
- Exclusive materials: Wood and leather production data only in 10W tests
- Limitation: Slower throughput on high-volume repeat production
- Best for: General production — industrial parts, nameplates, components
- Parameter style: Specific fixed values — production-ready, not exploratory
- Window: Comfortable adjustment margin for batch-to-batch material variation
- Operator experience: Forgiving — small deviations still produce acceptable results
- Transferability: 20W parameters are well-documented and widely referenced
- Best for: High throughput on repeat-production parts with stable material specs
- Power %: Significantly lower than 20W for the same effect — must re-calibrate when switching from 20W
- Window: Narrower than 20W — less tolerance for operator error on coatings and plastics
- Throughput: Same marking quality at higher speed vs 20W
- Not recommended: Color marking or highly varied material exploration
Fill Direction: The Control That Determines Black or White
Fill direction is one of the most important controls for determining whether a mark appears black or white on metal — often more influential than power or speed alone. This is the most commonly misunderstood aspect of fiber laser marking, and why operators sometimes struggle to consistently reproduce a specific result.
Single-direction fill
Parallel lines in one direction build a thick, uniform oxide layer. The layer absorbs light and appears dark. Fine spacing (0.01mm) and low frequency (80 kHz) concentrate the heat for maximum oxide build-up.
Cross-hatch fill
Two perpendicular scan passes create a micro-rough textured surface. This texture scatters incoming light in all directions, making the surface appear bright white. Higher speed (1000+ mm/s) keeps the oxide thin and reflective.
Why this works physically
Both effects use the same mechanism: laser-induced oxidation of the metal surface. The difference is oxide layer character. A thick, flat layer (single-direction, slow, fine spacing) absorbs rather than scatters light — it looks dark. A thin, textured layer with microscopic peaks and valleys (cross-hatch, faster speed) scatters light from its irregular surface — it looks bright white. The apparent color comes from the texture, not from the lines themselves.
Parameter Tables
All values are reference starting points from GWEIKE production tests. Speed in mm/s, frequency in kHz, fill spacing in mm. Test on your specific material before production — surface finish, alloy grade and coating thickness all affect the result.
| Effect | Fill spacing | Fill mode | Speed | Power | Frequency |
|---|---|---|---|---|---|
| Black mark | 0.01 mm | Single | 100–200 | 40% | 80 kHz |
| White mark | 0.05 mm | Cross | 1000 | 65% | 35 kHz |
| Deep black (standard) | 0.01 mm | Single | 200 | 40% | 80 kHz |
| Deep black (heavy) | 0.05 mm | Single | 500 | 80% | 20 kHz |
| Brushed finish — fine | 0.09 mm | Single | 1000 | 70% | 35 kHz |
| Brushed finish — medium | 0.12 mm | Single | 1000 | 70% | 35 kHz |
| Brushed finish — coarse | 0.25 mm | Single | 1000 | 70% | 35 kHz |
For 30W stainless steel: keep the same fill, mode, speed and frequency — reduce power by 25–30%. Full comparison in Section 6.
| Material | Effect | Fill | Mode | Speed | Power | Frequency |
|---|---|---|---|---|---|---|
| Anodized aluminum | Black mark | 0.01 | Single | 300 | 50% | 250 kHz |
| Tooling aluminum | White mark | 0.05 | Cross | 100 | 95% | 45 kHz |
| Aluminum alloy | Deep black | 0.01 | Cross | 200 | 100% | 30 kHz |
| Brass | White mark | 0.05 | Cross | 1000 | 80% | 40 kHz |
| Brass | Deep black | 0.01 | Cross | 100 | 95% | 20 kHz |
| Copper | Deep white | 0.02 | Single | 100 | 100% | 20 kHz |
| German silver | White mark | 0.03 | Cross | 1000 | 100% | 50 kHz |
| Silver | White mark | 0.05 | Cross | 1200 | 100% | 35 kHz |
| Iron sheet | White mark | 0.05 | Cross | 1000 | 55% | 35 kHz |
| Metal device housing | Black mark | 0.01 | Single | 100 | 100% | 20 kHz |
Anodized aluminum uses 250 kHz (maximum frequency) because the laser only needs to alter the anodized oxide coating, not penetrate the metal. Bare aluminum alloy needs much higher power for the same reason that stainless deep black uses low frequency — the mechanism is ablation rather than surface coloring.
| Material | Effect | Fill | Mode | Speed | Power | Frequency |
|---|---|---|---|---|---|---|
| Black hard plastic | White mark | 0.05 | Single | 1500–2000 | 60–75% | 25–45 kHz |
| White lamp cover | Black mark | 0.03 | Single | 1200 | 90% | 25 kHz |
| White plastic pipe | Matte black | 0.03 | Single | 1200 | 65% | 25 kHz |
| Red button / key | White mark | 0.01 | Cross | 1300 | 65% | 35 kHz |
| Black-painted white key | White mark (remove paint) | 0.04 | Cross | 1000 | 65% | 35 kHz |
| Blue-coated white surface | White mark | 0.03 | Single | 800 | 85% | 40 kHz |
| PCB / circuit board | White mark | 0.01 | Single | 1000 | 95% | 32 kHz |
Plastics require high speed to prevent thermal distortion — energy must pass through the mark zone faster than the material can accumulate damaging heat. Do not reduce speed to darken a plastic mark; reduce frequency instead. PCB marking uses near-full power because the laser must cut cleanly through the solder mask without penetrating to the fibreglass substrate.
| Material | Effect | Fill | Speed | Power | Frequency | Focal |
|---|---|---|---|---|---|---|
| Leather | Best contrast mark | 0.01–0.06 | 300 | 60% | 25 kHz | 272 mm |
| Wood | Surface char mark | 0.03 | 800 | 50% | 20 kHz | 272 mm |
Leather and wood marks are produced by carbonisation, not oxidation — a fundamentally different mechanism from metal marking. Leather is sensitive to cracking from heat build-up; 300 mm/s with 60% power is the stable window in our 10W tests. Wood char depth increases at lower speed and higher power; the 800 mm/s / 50% starting point gives a visible surface mark without excessive depth.
| Target shade | Fill | Speed | Power | Frequency | Note |
|---|---|---|---|---|---|
| Light mark | 0.01–0.03 | 1000+ | 20–40% | 20 kHz | Fast + low power |
| Mid-tone mark | 0.01–0.03 | 500–800 | 40–60% | 20 kHz | Mid range |
| Dark mark | 0.01–0.03 | 300–500 | 60–80% | 20 kHz | Slow + higher power |
On anodized aluminum the full tonal range from light to very dark is accessible by varying speed and power within these bands. The result varies significantly with anodising bath chemistry and layer thickness — always run a speed/power test grid on scrap from each material batch before production.
| Material | Effect | Fill | Speed | Power | Frequency | Focal |
|---|---|---|---|---|---|---|
| Anodized aluminum | Light to dark (speed controls) | 0.01–0.03 | 500 | 20–80% | 20 kHz | 272 mm |
| Aluminum nameplate | White to black | 0.01–0.03 | 1000 | 20–80% | 20 kHz | 272 mm |
| Plastic | Clean surface mark | 0.03 | 1000 | 20% | 20 kHz | 272 mm |
| Wood | Char mark | 0.03 | 800 | 50% | 20 kHz | 272 mm |
| Iron / mild steel | Light to black | 0.01–0.03 | 0–1000 | 20–80% | 20 kHz | 272 mm |
| Stainless steel | Full range — black to near-original | 0.01–0.06 | 0–1500 | 20–80% | 20 kHz | 272 mm |
| Leather | Best contrast mark | 0.01–0.06 | 300 | 60% | 25 kHz | 272 mm |
| Stainless steel | Color mark — Red | 0.01 | 40 | 40% | 20 kHz | 271.4 mm |
| Stainless steel | Color mark — Blue | 0.01 | 125 | 50% | 20 kHz | 271.4 mm |
| Stainless steel | Color mark — Green | 0.01 | 35 | 50% | 20 kHz | 271.4 mm |
10W parameters are exploration ranges — they show the operating window within which results change gradually. Run a test grid to find the exact point for your material batch, then pin down specific values for production. Focal length 272mm is standard; 271.4mm is used for color marking (–0.6mm offset).
20W vs 30W: Side-by-Side Comparison
The most consistent finding across all materials is that the 30W system requires significantly lower power percentages for the same visual result. Operators moving from 20W to 30W who carry over their percentage settings will overshoot every application.
| Material | Effect | Fill | 20W speed | 20W power | 30W speed | 30W power | Freq (both) |
|---|---|---|---|---|---|---|---|
| Stainless steel | White mark | Cross 0.05 | 1000 | 65% | 1000 | 35% | 35 kHz |
| Stainless steel | Black mark | Single 0.01 | 220 | 40% | 320 | 40% | 80 kHz |
| Stainless steel | Deep black | Single 0.05 | 500 | 80% | 500 | 50% | 20 kHz |
| Stainless steel | Brushed (fine) | 0.09 | 1000 | 70% | 1000 | 30% | 35 kHz |
| Stainless steel | Brushed (coarse) | 0.25 | 1000 | 70% | 1000 | 50% | 35 kHz |
| German silver | White mark | Cross 0.03 | 1000 | 100% | 1000 | 70% | 50 kHz |
| Iron sheet | White mark | Cross 0.05 | 1000 | 55% | 1000 | 35% | 35 kHz |
| Silver | White mark | Cross 0.05 | 1200 | 100% | 1200 | 80% | 35 kHz |
| Red button / key | White mark | Cross 0.01 | 1300 | 65% | 1300 | 45% | 35 kHz |
| White lamp cover | Black mark | Single 0.03 | 1200 | 90% | 1200 | 50% | 25 kHz |
| Tooling aluminum | White mark | Cross 0.05 | 100 | 95% | 120 | 80% | 45 kHz |
| Brass | White mark | Cross 0.05 | 1000 | 80% | 1000 | 80% | 40 kHz |
| PCB / circuit board | White mark | Single 0.01 | 1000 | 95% | 1000 | 95% | 30–32 kHz |
Color Marking on Stainless Steel (10W)
Fiber laser color marking on stainless steel produces permanent color without any paint, ink, or coating. The color comes from a thin-film interference effect in the oxide layer — the same physics that creates rainbow colors in soap bubbles and oil films. Different oxide layer thicknesses refract light at different wavelengths, producing different visible colors.
Why 10W and not higher power?
Color marking requires very precise control over oxide layer thickness — the difference between yellow and blue is a matter of nanometers. Higher-wattage machines deliver more energy per pulse, making the oxide layer grow faster and making it harder to hit the narrow window for each color. A 10W system with a slow scan speed provides the finest control. Our color marking data comes from 10W tests; higher-wattage color marking is possible in principle but has a much narrower operating window and requires re-calibration from scratch.
Focus offset for color marking
Color marking uses a slightly defocused beam: approximately –0.6mm from the standard focal length (271.4mm vs the standard 272mm for a 163mm field lens). The slight defocus increases the spot size, reducing peak power density and allowing finer control over heat input and oxide layer thickness.
| Target color | Fill spacing | Speed (mm/s) | Power | Frequency | Focus offset |
|---|---|---|---|---|---|
| Yellow | 0.01 mm | 800 | 100% | 40 kHz | –0.6 mm |
| Purple-red | 0.03 mm | 99 | 100% | 80 kHz | –0.6 mm |
| Blue | 0.025 mm | 500 | 100% | 80 kHz | –0.6 mm |
| Black | 0.01 mm | 80–100 | 100% | 35 kHz | –0.6 mm |
| Green | 0.003 mm | 800 | 100% | 80 kHz | –0.6 mm |
- Clean the surface thoroughly before color marking — fingerprints and oils create irregular oxide growth that ruins color uniformity
- Green requires very fine fill spacing (0.003mm) — confirm your software is not rounding this to a coarser value
- Color shifts slightly with viewing angle — this is inherent to thin-film interference and not a defect; evaluate under consistent lighting conditions
- Do not touch the marked area after marking — the oxide layer is stable but mechanically fragile before any protective coating is applied
Troubleshooting
Mark is grey, not true black (stainless steel)
Cause: Oxide layer too thin — not enough energy per scan line. Most commonly caused by speed too high, power too low, or frequency too high (energy spread too thin across many pulses).
Fix: Reduce speed by 20% first and re-test. If still grey, reduce frequency from 80 kHz to 50 kHz. If still grey, increase power by 10%. Change only one variable at a time. Target: 100–200 mm/s, 80 kHz or below, 40–50% power (20W). A bronze or copper tone means you are close — slightly lower frequency will push it into black.
Mark is grey or patchy, not true white (stainless steel)
Cause: Cross-hatch pattern not producing uniform light scattering. Most common causes: fill spacing too fine (0.01mm instead of 0.05mm), speed too slow, or fill direction is set to single rather than cross-hatch.
Fix: Confirm fill mode is cross-hatch (two perpendicular passes), not single direction. Increase fill spacing to 0.05mm. Increase speed to 1000+ mm/s. For white marks, counterintuitively, less energy is often better — the goal is a very thin, highly reflective oxide layer, not a thick dark one.
Plastic is deforming or melting around the mark
Cause: Thermal energy accumulating in the plastic because scan speed is too slow. Plastics have low thermal conductivity — heat builds up near the mark zone before it can dissipate.
Fix: Increase speed to 1500–2000 mm/s. This is the correct first step on plastics, not power reduction. If the mark is too light at high speed, increase power by 10% increments — do not reduce speed. Also check fill spacing is not too fine; 0.03–0.05mm is typically better for plastics than 0.01mm.
Color marks are inconsistent across the part (10W)
Cause: Surface contamination, inconsistent focal distance, or material batch variation. Color marking is significantly more sensitive to all three than standard black/white marking.
Fix: Clean the surface with isopropyl alcohol and a lint-free cloth immediately before marking — do not touch after cleaning. Check that the workpiece is flat on the fixture; even 0.5mm height variation across a large part shifts the color. If color is consistent within a batch but shifts between batches, the alloy or surface treatment has changed at source — include a reference coupon from each material batch in your quality process.
30W marks are much darker or deeper than expected
Cause: 20W parameter settings applied directly to a 30W machine without adjusting power percentage — very common when operators change machines.
Fix: Start with the 30W column values in Section 6 — power percentage is typically 25–35% lower than 20W values. Speed and frequency transfer more directly. Run a test sequence on scrap material before resuming production. Do not apply 20W power settings to a 30W machine, even temporarily.
Not getting the result you need on your material?
Material surface finish, alloy grade and coating thickness all shift the parameter window from the starting values in this guide. If you are working with a non-standard alloy, a specific surface treatment, or a marking specification that requires verification, our applications team can run test marks on your sample and confirm parameters for your production setup.
FAQ
How do I get a white mark vs a black mark on stainless steel?
The fill pattern is the primary control. A cross-hatch fill (two perpendicular scan passes) at 0.05mm spacing produces white by creating a micro-rough oxide surface that scatters light. A single-direction fill at slow speed and low frequency builds a thick, light-absorbing oxide layer that appears black. White starting point: cross fill 0.05mm, speed 1000 mm/s, power 65% (20W) or 35% (30W), frequency 35 kHz. Black starting point: single fill 0.01mm, speed 100–200 mm/s, power 40%, frequency 80 kHz.
Why does a 30W marker use lower power percentage than a 20W for the same result?
Power percentage is relative to rated output. A 30W machine at 35% deposits more energy per pulse on the material surface than a 20W at the same percentage — the absolute wattage is higher, so the same percentage translates to a larger heat input. Using 20W percentage settings on a 30W machine tends to overdrive the oxidation reaction, producing scorching or blown-out marks rather than clean ones. As a starting rule, reduce power by 25–35% when moving from 20W to 30W settings and fine-tune from there. This pattern applies to most surface marking effects; deep engraving may differ. Speed and frequency transfer more reliably.
What parameters do I need for color marking on stainless steel?
Color marking is most consistently achieved on a 10W system, though higher-wattage machines can also produce color marks with careful calibration. Reference starting values for 10W with a 163mm field lens: Yellow — fill 0.01mm, speed 800 mm/s, 100% power, 40 kHz, focus offset –0.6mm. Blue — fill 0.025mm, speed 500 mm/s, 100% power, 80 kHz. Green — fill 0.003mm, speed 800 mm/s, 100% power, 80 kHz. Focus offset values apply to a 163mm field lens setup — adjust for other lens configurations. Color results are highly sensitive to surface condition and alloy grade — always test on the production part.
What is the difference between 10W, 20W and 30W fiber laser markers?
Beyond raw power, the differences are in operating pattern and capability. A 10W system provides wide exploratory parameter ranges and is the most practical for color marking on stainless. A 20W system gives reliable, repeatable production parameters with comfortable adjustment margin. A 30W system offers the fastest throughput for high-volume production but requires proportionally lower power percentages — operators cannot carry 20W settings directly to a 30W machine. All three mark the same metals, plastics and coatings; the differences are throughput, parameter sensitivity, and color marking capability.
Does frequency affect mark depth or just speed?
Frequency and speed both affect energy per area but through different mechanisms. Speed controls dwell time — how long the laser stays on each point. Frequency controls pulse energy — at 20 kHz each pulse is more energetic and penetrates deeper; at 250 kHz the same average power is spread across many shallow pulses. For deep marks and annealing, use low frequency (20–80 kHz). For surface-only marks on anodized materials and coatings, use high frequency (80–250 kHz). Adjusting only speed without considering frequency produces suboptimal results at both extremes.
Why does my black mark look brown or bronze instead of black?
Brown or bronze means the oxide layer is forming at a lower temperature than needed for true black — the laser is heating the surface but not quite reaching the thick black oxide window. Try reducing speed from 500 to 200 mm/s and reducing frequency from 80 kHz to 50 kHz, keeping power the same. If still bronze, reduce frequency further to 35 kHz. Bronze is an intermediate oxide state — each step builds a thicker layer and pushes the result toward black.
