When setting up a fiber laser engraver, three of the most important parameters are power, speed, and frequency. These settings directly affect engraving depth, marking darkness, surface finish, and processing efficiency.
For MOPA fiber lasers, there is one more important parameter to understand: pulse width. By adjusting pulse width, you can further control how the laser interacts with different materials.
In this guide, we explain how laser engraving power, speed, frequency, and MOPA pulse width work, how they interact, and how to adjust them for common engraving applications.
What Do Power, Speed, and Frequency Mean in Laser Engraving?
- Power: The laser output level, usually expressed as a percentage.
- Speed: The scanning speed of the galvanometer, usually measured in mm/s.
- Frequency: The number of laser pulses emitted per second, usually measured in kHz.
These three parameters work together to control how much energy reaches the material, how long it stays there, and how densely the pulses overlap.
Laser Power
Laser power controls the amount of laser energy delivered during processing. It strongly affects engraving depth, marking darkness, and the amount of material removed. When you increase power, more energy is delivered to the material, so the engraving tends to become deeper and darker. Material removal and ablation become stronger, and metal surfaces can darken more easily. However, too much power may cause overburning, bubbling, scorching, or workpiece deformation.
When you reduce power, less energy is applied to the material. The engraving becomes shallower and lighter, lines may become thinner, and the result is more suitable for light marking. If power is too low, the mark may become faint or may not appear clearly.
Important: Higher power is not always better. Excessive power can damage the material surface and may cause burrs, burnt edges, or unwanted thermal effects.
Laser Speed
Laser engraving speed determines how quickly the laser beam moves across the workpiece. The faster the laser moves, the less time it stays on each area. The slower it moves, the longer the exposure time and the higher the accumulated energy.
When speed is increased, the laser spends less time on the material, total energy input per area decreases, and the engraving becomes lighter and shallower. Higher speeds are useful for fast marking and light engraving. If the speed is too high, lines may become faint, incomplete, or discontinuous.
When speed is reduced, the laser remains on the material for longer, accumulated energy increases, and the mark becomes darker and deeper. If the speed is too low, the material may overheat, blacken, carbonize, or develop blurred edges.
Key relationship: Power and speed work together. If power is increased, speed can usually be increased accordingly. If power is reduced, speed may also need to be reduced to maintain a similar marking effect.
Laser Frequency
Laser frequency refers to the number of laser pulses emitted per second. It affects pulse overlap, line smoothness, engraving texture, and marking appearance.
At higher frequency, more pulses are emitted within the same period, pulse spacing becomes denser, spot overlap increases, and lines generally appear smoother and finer. This is suitable for fine marking and grayscale images. At lower frequency, pulses are more widely spaced, spot overlap decreases, and the marking texture becomes more noticeable, which can be suitable for applications where deeper engraving is required.
For metals such as stainless steel and aluminum, higher frequency produces finer lines and more uniform surface processing, suitable for dark marking and detailed logos. Lower frequency concentrates pulse action and can be useful for deeper engraving, although the surface may appear more textured.
For plastic, wood, and acrylic, very high frequency may increase heat accumulation and cause burning or carbonization, so reducing frequency appropriately can help reduce excessive heat buildup.
Important: Frequency controls pulse density rather than simply acting as another power setting. Under the same average power conditions, increasing the frequency means the energy is distributed across more pulses.
How Power, Speed, and Frequency Work Together
The best fiber laser settings are usually found by adjusting power, speed, and frequency together rather than changing only one parameter. The goal is to balance energy input, exposure time, and pulse density so the material receives the right amount of heat for the desired result.
For Deeper and Darker Engraving
To achieve deeper and darker engraving, increase power and reduce speed. This delivers more energy and keeps it on the material for longer. Adjust frequency as needed to maintain a finer marking surface. If the result becomes too rough or burned, frequency and speed can be fine-tuned to improve surface quality.
For Light, Detailed, or Grayscale Marking
For light, detailed, or grayscale marking, reduce power and use a lower or moderate speed. Increase frequency to improve spot overlap and detail. This combination helps create finer lines, smoother shading, and less thermal damage.
For Fast Batch Marking
For fast batch marking, increase speed and increase power accordingly. Use a moderate frequency. The higher speed reduces processing time, while the added power helps maintain a visible mark. A moderate frequency keeps the mark consistent without overcomplicating the setup.
Fiber Laser Settings Reference Table
The following settings are starting-point references for fiber laser marking. Actual parameters should be adjusted according to the material, focus, lens size, and desired result.
| Application | Power | Speed | Frequency |
|---|---|---|---|
| Black marking on stainless steel | 60–80% | 100–300 mm/s | 40–80 kHz |
| Light logo marking on metal | 30–50% | 300–800 mm/s | 30–60 kHz |
| Deep engraving | 70–90% | 50–150 mm/s | 20–40 kHz |
| Plastic marking | 20–40% | 200–500 mm/s | 20–40 kHz |
| Grayscale photo marking | 40–60% | 200–400 mm/s | 60–100 kHz |
Note: These settings are for reference only. Actual results depend on material composition, focus, lens size, machine configuration, and other processing conditions.
MOPA Fiber Laser Notes
Standard Q-switched fiber lasers normally use a fixed pulse width. MOPA fiber lasers, however, allow the pulse width to be adjusted. Pulse width describes how long each laser pulse lasts and is usually measured in nanoseconds, or ns.
Pulse width changes how the laser energy interacts with the material. A short pulse width gives a shorter laser-material interaction time, a smaller heat-affected zone, less melting, and cleaner edges. A long pulse width gives a longer heating time, a stronger thermal effect, more melting, oxidation, and material heating.
1. Short pulse width (about 2–6 ns): Very short laser-material interaction time. Less heat spreads into the surrounding material, producing clean edges and fewer burrs. Suitable for fine marking on stainless steel, anodized aluminum, grayscale images, thin parts, and heat-sensitive workpieces, although deep engraving efficiency may be lower.
2. Medium pulse width (about 8–20 ns): Balances impact and thermal effects. Provides some engraving depth without excessive edge burning. Suitable for general logos, characters, and common metal marking applications.
3. Long pulse width (about 30–200 ns): Produces a stronger thermal effect. More heat is transferred into the material and can create deeper material removal. Edges may develop burrs, discoloration, melting, or thermal deformation. Suitable for deeper metal engraving, coating removal, and heavier material processing.
For a simple comparison test, keep power, speed, frequency, and focus unchanged and adjust only the pulse width. For example, with a 30W MOPA fiber laser, you can set power at 50%, speed at 200 mm/s, frequency at 50 kHz, and test pulse widths of 4 ns, 10 ns, 30 ns, and 80 ns.
- At 4 ns, you can expect fine marking, clean edges, a uniform black appearance, and minimal burrs.
- At 10 ns, the result is balanced with moderate depth.
- At 30 ns, slight edge melting may begin to appear.
- At 80 ns, more obvious melting, burrs, and uneven darkening may appear.
By material, black marking on anodized aluminum usually uses a short pulse width of approximately 3–6 ns. Black marking and grayscale images on stainless steel usually use a short pulse width of approximately 4–8 ns. Bare 6061 aluminum often uses a medium pulse width. Deep engraving on metal may use a longer pulse width of approximately 50–120 ns. Plastic and PCB marking usually uses a shorter pulse width to reduce excessive burning.
Common Fiber Laser Setting Mistakes
1. Increasing power without adjusting speed: Using excessive power while keeping speed too low may burn the workpiece and create burnt edges.
2. Adjusting only speed: If the speed is too high, the laser may not leave a clear mark. If the speed is too low, the material may overheat.
3. Changing frequency without considering the material: An unsuitable frequency may lead to excessive burning on some plastics or a coarse marking texture on metals.
Simple rule
Power controls engraving intensity.
Speed controls exposure time.
Frequency controls pulse density.
Conclusion
There is no single set of laser parameters that works perfectly for every material. When adjusting your fiber laser settings, remember that power mainly affects engraving intensity and depth, speed controls how long the laser interacts with the material, frequency controls pulse density and overlap, and MOPA pulse width controls the duration of each laser pulse and changes the thermal characteristics of the process.
- Power mainly affects engraving intensity and depth.
- Speed controls how long the laser interacts with the material.
- Frequency controls pulse density and overlap.
- MOPA pulse width controls the duration of each laser pulse and changes the thermal characteristics of the process.
Start with conservative settings, make small adjustments, and test on the actual material before beginning production.
