Handheld Laser Cutting Safety Parameters: How to Set Gas Pressure, Peak Power and PWM

Practical commissioning and troubleshooting guide for 800 W and 1200 W handheld fiber lasers. Learn how to avoid incomplete cuts, over-burning, heavy burr and nozzle damage by controlling three core parameters.

In handheld fiber laser cutting, most quality problems do not come from the operator’s hand, but from three basic parameters: shielding gas pressure, peak power and PWM duty cycle / frequency. If these three are under control, 800 W and 1200 W handheld systems can cut thin stainless steel, carbon steel, aluminum and brass cleanly and safely.

This guide is based on GWEIKE’s in-factory tests with 800 W and 1200 W handheld fiber lasers. You can use it as a practical template when commissioning new machines, training operators or troubleshooting existing jobs.

Typical Problems When Parameters Are Wrong

On the shop floor, handheld cutting issues usually fall into four categories:

Not Cutting Through

  • Kerf is visible but the part does not separate.
  • Back side shows partial penetration or strong discoloration.
  • Often caused by insufficient peak power, too low gas pressure or cutting speed that is too high.

Over-burning and Deformation

  • Edge turns dark blue or black.
  • Thin sheet warps or shrinks around the cut.
  • Typical reasons: peak power too high and cutting speed too low, heat accumulates faster than it can escape.

Heavy Burr and Slag

  • Thick burr on the bottom side, difficult to remove mechanically.
  • Kerf looks narrow on the top, but “closed” at the bottom by re-solidified metal.
  • In most cases gas flow cannot blow the molten pool out of the kerf, or the focus position is wrong.

Burning or Damaging the Nozzle

  • Nozzle turns dark, gets splatter inside or goes visibly off-center.
  • Cut quality degrades suddenly and remains unstable.
  • Root causes: gas pressure too low, wrong stand-off distance, or instable beam due to damaged nozzle / optics.

The good news: all four problems can usually be corrected by systematic adjustment of gas pressure, peak power and speed, while keeping PWM settings stable.

Parameter #1 – Gas Pressure (6–8 bar N2)

For handheld cutting we recommend nitrogen as the main process gas for stainless steel, carbon steel, aluminum and brass. In our tests, the effective window for all four materials and thicknesses from 1.0–4.0 mm is:

  • Pressure: 6–8 bar N2
  • Too low (<6 bar): incomplete penetration, strong burr.
  • Too high (>8 bar): unstable melt pool, wider kerf, noisy jet.

Recommended Pressure by Thickness

Material Thickness Start Pressure Max Pressure Notes
Stainless / Carbon steel 1.0 mm 6 bar 7 bar Fine cutting, minimal discoloration.
Stainless / Carbon steel 2.0 mm 7 bar 8 bar Use higher pressure if burr appears.
Stainless / Carbon steel 3.0–4.0 mm 7–8 bar 8 bar Full 8 bar recommended for continuous cutting.
Aluminum / Brass 1.0–2.0 mm 6–7 bar 8 bar Soft materials, start lower and increase as needed.

As a rule of thumb: if the cut is not clean, first try +1 bar before changing power or speed.

Parameter #2 – Peak Power (% of Rated Power)

Peak power controls how much energy is concentrated into the cutting front. In our tests with 1200 W handheld fiber, the following settings produced clean cuts on stainless steel:

Laser Power Material Thickness Cutting Speed Peak Power Gas Pressure
1200 W Stainless steel 1.0 mm 18 mm/s 65 % N2 6–8 bar
1200 W Stainless steel 2.0 mm 12 mm/s 75 % N2 6–8 bar
1200 W Stainless steel 3.0 mm 8 mm/s 85 % N2 6–8 bar
1200 W Stainless steel 4.0 mm 6 mm/s 95 % N2 6–8 bar

For 800 W handheld cutting the trend is similar, but shifted ~10 % higher:

  • 1.0 mm steel – about 75 % peak power.
  • 2.0 mm steel – about 85 % peak power.
  • 3.0 mm steel – about 95 % peak power.

Rule of thumb: every additional millimetre of thickness requires roughly +10–15 % peak power (up to 95 %). Working permanently at 100 % is not recommended, as it increases thermal load on the fiber source.

When you face incomplete penetration and gas pressure is already at 7–8 bar, the first corrective move should be: +10 % peak power and -20 % cutting speed.

4. Parameter #3 – PWM Duty Cycle and Frequency

In the handheld cutting parameter table, all tested conditions use:

  • PWM duty cycle: 100 %
  • PWM frequency: 1000 Hz
  • Scanning frequency: 5 Hz
  • Scan width: 0 mm (no wobble)

This is not an accident. For manual cutting, the process window is much easier to control with a continuous, stable energy delivery. Low duty cycles and complex pulsing patterns are more sensitive to hand movement and stand-off fluctuation.

Therefore, our recommendation for production work is simple:

  • Keep 100 % duty cycle and 1000 Hz frequency for most handheld cutting tasks.
  • Only advanced users should experiment with lower duty cycles, and always on test pieces first.

5. Standard Troubleshooting Workflow

When something goes wrong, avoid changing many settings at once. Follow this step-by-step workflow instead.

5.1 Problem: The Sheet Does Not Cut Through

  1. Check gas pressure: increase by 1 bar (e.g. from 6 → 7 bar).
  2. Increase peak power by 10 % (e.g. 65 % → 75 %).
  3. Reduce speed by 20 % (e.g. 12 mm/s → 9–10 mm/s).
  4. Verify focus position: for thin sheet, keep the focal point slightly below surface (-0.5 mm).

5.2 Problem: Heavy Burr or Slag

  1. Raise gas pressure (7 → 8 bar).
  2. Increase speed by 10–20 % if the kerf is very wide.
  3. Check the nozzle for contamination or deformation; replace if burned or bent.
  4. Ensure stand-off distance is stable while moving the hand torch.

5.3 Problem: Burn Marks and Strong Discoloration

  1. Reduce peak power by 10 %.
  2. Increase cutting speed moderately (e.g. 8 → 10 mm/s).
  3. Confirm gas pressure is at least 6–7 bar to cool the edge properly.

5.4 Problem: Nozzle Burning

  1. Stop cutting and clean or replace the nozzle immediately.
  2. Verify gas pressure (should not be below 6 bar during cutting).
  3. Check if the nozzle tip is concentric with the beam (simple burn-paper test).
  4. If problems persist, inspect protective lens and front optics.

6. Reference Tables for 800 W and 1200 W Handheld Cutting

The following tables summarise our recommended starting points for handheld cutting.

6.1 1200 W Handheld Fiber Laser

Material Thickness Speed Gas Pressure Peak Power
Material Thickness Speed Gas Pressure Peak Power
Stainless steel 1.0 mm 18 mm/s N2 6–8 bar 65 %
Stainless steel 2.0 mm 12 mm/s N2 6–8 bar 75 %
Stainless steel 3.0 mm 8 mm/s N2 6–8 bar 85 %
Stainless steel 4.0 mm 6 mm/s N2 6–8 bar 95 %
Carbon steel 1.0–4.0 mm 18 / 12 / 8 / 6 mm/s N2 6–8 bar 65–95 %
Aluminum 1.0–4.0 mm 18 / 12 / 8 / 6 mm/s N2 6–8 bar 65–95 %
Brass 1.0–2.0 mm 12 / 8 mm/s N2 6–8 bar 75–95 %

6.2 800 W Handheld Fiber Laser

Material Thickness Speed Gas Pressure Peak Power
Material Thickness Speed Gas Pressure Peak Power
Stainless steel 1.0 mm 12 mm/s N2 6–8 bar 75 %
Stainless steel 2.0 mm 8 mm/s N2 6–8 bar 85 %
Stainless steel 3.0 mm 6 mm/s N2 6–8 bar 95 %
Carbon steel 1.0–3.0 mm 12 / 8 / 6 mm/s N2 6–8 bar 75–95 %
Aluminum 1.0–3.0 mm 12 / 8 / 6 mm/s N2 6–8 bar 75–95 %
Brass 1.0 mm 8 mm/s N2 6–8 bar 95 %

Note: The tables above are starting points. Always fine-tune speed and peak power by ±10 % on your own material and fixture.

7. Next Steps

If you want to standardise handheld cutting in your workshop, we recommend creating your own “process cards” based on the tables above and placing them next to the machine. For larger projects, our process engineers can help you optimise parameters for special materials, mixed-gas cutting and combined welding–cutting jobs.

Contact GWEIKE to get the full 6-in-1 process chart (cutting, welding, cleaning and marking) tailored to your application.