When using a 12kW Fiber Laser Cutter it is best to adjust focus positioning, focus & focal adjustment, oxygen pressure and cutting speed for optimal results. Below is a case study on cutting 20 mm Stainless Steel.

laser cutting parameters 12kW at 20 mm Stainless

Power: 12000w
Nozzle selection: 5.0
Cutting focus: -12.5
Cutting speed: 1.1m/min
Duty cycle: 90%
Frequency: 600Hz
Cutting height: 0.5mm
Cutting air pressure: 3000kpa


Here, six cuts were made using heights of 0.3mm, 0.5mm, 0.7mm, 0.9mm, 1.1mm, and 1.3mm.

0.3mm height allows the cutting head to jump resulting in unstable cutting.

Height past 0.5mm results in bottom slag.

Thus, 0.5mm is the optimal cutting height.

laser cutting stainless adjusting frequency


Frequencies of 400Hz, 600Hz, 800Hz, 1000Hz, and 5000Hz were compared.

At 800-5000Hz, there was noticeable slag accumulation across the bottom of the cuts.

At 400 Hz, the cut grooves are very deep.

As a result, 600Hz was determined to be the best option.

Duty Cycle

The duty cycle was tested at 70%, 80%, 90%, and 100%.

Duty cycles of 70% and 80% both resulted in stratification of the cutting surface.

100% duty cycle resulted in excessive bottom slag.

90% duty cycle was proved to provide the cleanest cut.

laser cutting duty cycle comparison
laser cutting stainless focus position comparison
laser cutting stainless focus comparison
laser cutting stainless large focus results

Laser Focus

Cutting focus of 10, 11, 12, and -12.5 were tested.

For cutting stainless steel, using negative focus cutting is recommended. This approach results in a uniformly good edge quality. To achieve the best results, a negative focus is applied at the perforation position. This helps in minimizing the spot size and maximizing the energy density at that specific spot. Furthermore, as the perforation position gets deeper, it is advisable to increase the negative focus for optimal perforation results.

If the focus is too small, hard slag will form in one direction and there will be black along the cut.

If the focus is too large, the bottom slag will be dripping and discontinuous and the cutting surface will be layered with rough drag lines.