Laser Cutting Technology

Laser cutting technology is widely utilized for processing both metal and non-metal materials. It effectively shortens processing time, lowers processing costs, and enhances the quality of the finished product.

Laser cutting is accomplished through the application of high power density energy that is generated by focusing the laser. In comparison to traditional sheet metal processing techniques, laser cutting boasts advantages such as high cutting quality, fast cutting speed, exceptional flexibility, and versatility with a wide range of materials.

Laser melt cutting

In laser melt cutting, the workpiece is partially melted and the molten material is expelled by a stream of gas. The process is named as such because material transfer only occurs in its liquid state.

The laser beam is paired with a high-purity inert gas to facilitate the removal of the molten material from the cut, while the gas itself does not contribute to the cutting process.

Compared to gasification cutting, laser melt cutting can result in higher cutting speeds. This is because the energy required for gasification is typically higher than the energy needed to melt the material.

The laser beam in laser melt cutting is only partially absorbed. The maximum cutting speed increases with the laser power, but decreases as the thickness of the sheet and the melting temperature of the material increase.

When the laser power is constant, the limiting factors are the air pressure at the kerf and the thermal conductivity of the material.

Laser melt cutting provides a clean, oxide-free cut for iron and titanium materials. The laser power density that induces melting but not gasification is between 104 W/cm² and 105 W/cm² for steel materials.

Laser flame cutting

Laser flame cutting is a cutting method that utilizes oxygen as the cutting gas, which distinguishes it from laser melting cutting. The interaction between the heated metal and oxygen creates a chemical reaction that further heats the material. For structural steels of the same thickness, this method results in a higher cutting rate compared to melt cutting.

However, laser flame cutting can produce lower cut quality than melt cutting. It is known to result in wider slits, roughness, a larger heat affected zone, and poor edge quality. This method is not suitable for machining precision models or cutting sharp corners as there is a risk of burning.

To mitigate the thermal effects, pulse mode lasers can be used. The cutting speed is determined by the laser power used. When the laser power is constant, the supply of oxygen and the material’s thermal conductivity become the limiting factors.

Laser gasification cutting

In the laser gasification cutting process, the material is vaporized at the kerf, requiring a very high laser power. To prevent the material vapor from condensing on the slit wall, the material thickness must not exceed the diameter of the laser beam.

This process is only suitable for applications where it is necessary to avoid the exclusion of molten material. It is limited to a small field of use for iron-based alloys. This process cannot be used for materials such as wood and certain ceramics that cannot be melted and are therefore less likely to condense the material vapor. Additionally, these materials typically require thicker cuts.

The optimal beam focus in laser gasification cutting is dependent on the material thickness and beam quality. Although laser power and heat of vaporization do have an impact, they are not the only factors that determine the optimal focus position.

The required laser power density for this process is greater than 108 W/cm2 and varies based on the material, depth of cut, and beam focus position. When the sheet thickness is constant and assuming sufficient laser power, the maximum cutting speed is limited by the velocity of the gas jet.