Laser Cutting Essentials: Optimal Parameters Guide

Last updated:
January 24, 2024

Table Of Contents

The main parameters for laser cutting include laser cutting power and speed, lens focal length and focal point position, nozzle shape and distance from the nozzle to the workpiece surface, as well as the type and pressure of the assist gas.

Laser Cutting Power and Cutting Speed

Cutting speed is a crucial parameter for cutting. During cutting, the cutting speed needs to be determined based on the laser power, gas pressure, and workpiece thickness. It increases with the increase in laser power and gas pressure, and decreases with the increase in workpiece thickness. For instance, when cutting a 6mm carbon steel plate, the cutting speed is 2.5m/min, while for a 12mm carbon steel plate, the cutting speed is 0.8m/min.

Lens Focal Length and Focal Point Position (Defocus Amount)

A smaller lens focal length results in higher power density but shallower focus, making it suitable for high-speed cutting of thin materials. Conversely, a larger lens focal length leads to lower power density but deeper focus, making it suitable for slow cutting of thick materials.

The defocus amount’s impact on the width of the cut is shown in Figure 5-3. Generally, the focal point is chosen to be located approximately 1/3 of the plate thickness below the workpiece surface, at which point the cut width is minimized.

Figure 5-3: The impact of defocus amount on the width of the cut.

Nozzle Shape and Nozzle-to-Workpiece Distance

(1) Selection of Nozzle Shape

The shape and size of the nozzle are crucial parameters affecting the quality and efficiency of laser cutting. Different cutting methods require different nozzle shapes. Common shapes for laser oxygen cutting nozzles are illustrated in Figure 5-4.

Figure 5-4: Common shapes of nozzles used in laser oxygen cutting

(2) Nozzle-to-Workpiece Distance

When the nozzle is too close to the workpiece surface, it affects the ability to blow away splattered molten slag. However, if the nozzle is too far from the workpiece surface, it can result in unnecessary energy loss. To ensure cutting stability, the distance from the nozzle end to the workpiece surface is generally controlled within 0.5 to 2mm.

Types and Pressure of Assist Gas

When using oxygen as the assist gas for cutting low carbon steel, intense oxidation reactions generate a large amount of heat, increasing cutting speed and thickness, and producing slag-free cuts. For cutting stainless steel, a mixture of oxygen and nitrogen is often used, resulting in better cut quality compared to using oxygen alone.

Increasing gas pressure enhances slag removal capability and can lead to higher cutting speeds. However, excessive pressure can result in rough cutting surfaces. See Table 5-1 for the main parameters and characteristics of laser cutting.

Table 5-1: Main parameters and characteristics of laser cutting

Workpiece MaterialsWorkpiece Thickness (mm)Laser Power (W)Cutting speed (cm/min)Cutting gasCharacteristics and Applications
99% alumina ceramic0.7830Controlled fracture
Crystalline quartz0.81360
Ferrite sheet0.22.5114
Sapphire1.2127
Quartz tube500400 pieces per hourMaterial saving and high-quality cutting when cutting quartz tubes, suitable for manufacturing halogen lamp tubes
Fabric20~250500~300AirMaterial saving, high-quality cutting, high efficiency, self-locking edges when cutting fabrics, suitable for manufacturing typewriter ribbons, umbrella surfaces, clothing, etc.
Glass tube12.720000460AirHigh-quality cutting of glass tubes without tool wear
Oak1630028AirHigh-quality cutting of wood, neat cutting edges, material saving, suitable for furniture manufacturing
Pine5020012.5Air
Boron epoxy resin board8.115000165AirHigh efficiency when cutting boron epoxy resin boards, no tool wear, suitable for aircraft component manufacturing
Low carbon steel1.5
3
1.0
6.0
16.25
35
300
300
1000
1000
4000
4000
300
200
900
100
114
50
OxygenHigh-quality cutting, labor and material saving, can replace milling, punching, and shearing, used in the manufacturing of instrument panels, heat exchangers, and automotive parts
30CrMnSi1.5
3.0
6.0
500
500
500
200
120
50
OxygenCan replace milling, punching, and shearing, high cutting efficiency, high-quality cutting, used in aircraft component manufacturing, no cutting deformation, material and labor saving, used in the manufacturing of aircraft components, helicopter rotors, etc.
Stainless steel0.5
2.0
3.175
1.0
1.57
6.0
4.8
6.3
12
250
250
500
1000
1000
1000
2000
2000
2000
450
25
180
800
456
80
400
150
40
OxygenNo cutting deformation, material and labor saving, used in the manufacturing of aircraft components, helicopter rotors, etc.
Titanium alloy3.0
8.0
10.0
40.0
250
250
250
250
1300
300
280
50
OxygenFast cutting speed, high-quality cutting, can replace milling, grinding, and chemical etching, labor saving, high cutting efficiency, used in aircraft component manufacturing
Titanium-clad aluminum honeycomb panel30350500OxygenNo cutting deformation, no damage to the workpiece surface, fast cutting speed, used in aerospace component manufacturing
Double-sided coated steel plate0.5~2.0350300OxygenLabor and material saving, does not damage surface coatings during cutting, used in air conditioning manufacturing
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