The IR-20 is a 20 W fiber laser module that can be retrofitted to almost all Sculpfun models (S6-A9 and S40/S70). With 20 W of power, it can even cut (thin) metals and, of course, engrave with excellent results.
Technical data:
| Power | 20 W |
| Wavelength | 1064 nm |
| Frequency | 30 – 60 kHz |
| Spot size | 0,05 mm |
Setup
Sculpfun offers a video tutorial for installation:
Explanation of settings
With this laser, you can adjust not only the speed and power, but also the frequency. For most users of diode lasers, this is a new parameter, which I will briefly explain here:
Frequency
Frequency refers to how many laser pulses per second the laser emits. 30–60 kHz means 30,000 to 60,000 pulses per second. The average power remains 20 W, but it is distributed over more or fewer pulses. This changes the energy per pulse: Energy per pulse = power ÷ frequency.
Specific figures (at 100% power; less power naturally means less energy)
- At 30 kHz: 20 W ÷ 30,000 ≈ 0.000667 J = 0.667 mJ per pulse.
- At 60 kHz: 20 W ÷ 60,000 ≈ 0.000333 J = 0.333 mJ per pulse
What does this mean in practice?
- Low frequency (≈30 kHz): Fewer pulses, but each pulse is stronger. This is good for deeper material removal per pulse or notches/engravings with more contrast. Edges may be rougher, and “splatter” is more likely.
- High frequency (≈60 kHz): More pulses, but each pulse is weaker. This is good for smoother, more even surfaces, fine markings, and fewer microcracks. The process is “gentler”, but often requires a higher scanning speed to prevent heat buildup.
Rule of thumb: Increase frequency → decrease pulse energy (finer, smoother). Decrease frequency → increase pulse energy (stronger, deeper). The optimal setting depends on the material, desired depth, and surface quality.
Higher energies at lower frequencies are advantageous for cutting processes, while higher frequencies are better for marking.
Connection with speed
- High speed: The laser spends less time at each point. Less energy per millimeter is delivered, the pulses are further apart, and they overlap less. Result: a flatter, cooler process, typically with a slightly rougher texture, but with a smaller heat-affected zone.
- Low speed: Longer dwell time, more energy per millimeter, pulses are denser and overlap more. Result: deeper ablation/weld seam, smoother surface possible, but more heat input and potential for burrs or discoloration.
Interaction with the frequency on the IR-20 (30–60 kHz):
- If the frequency is increased, each individual pulse becomes weaker, but more pulses occur in succession. At unchanged speed, the overlap increases.
- Lowering the frequency makes each pulse stronger, but there are fewer pulses; the overlap decreases at the same speed.
Practical tip: If the frequency is increased and the processing image is to remain the same, the scanning speed must also be increased accordingly. Example: For a spot of approximately 50 micrometers, around 1.25 m/s is typical for medium overlap at 50 kHz; at 60 kHz, around 1.5 m/s is required to maintain the same visual impression. However, these speeds can never be achieved with the available laser systems. It is therefore not possible to avoid overlap (pulse spacing for 50% overlap: 25 µm). Nevertheless, the ratio remains the same.
