What is CNC Laser Cutting?

Generally speaking, a laser emits a powerful beam of light through a process referred to as optical amplification. A laser is different to other types of light sources because it is able to concentrate all of the light generated into a narrow beam, over both short and long distances. This enables the laser to focus this light, and the heat generated as a result, on very small and precise surface areas. The precision and accuracy is what makes it the perfect technique to cut sheetmetal efficiently, consistently, and precisely. 

One of the most transformative developments in laser cutting is the ability to pair an optical laser with computer numerical control (CNC). By programming the movements of the laser into a computer through software, CNC laser cutting allows a technician to precisely burn, melt, or vaporise certain parts of the sheetmetal. By removing human error, the process is made more cost efficient, metal cutting is more consistent over larger production runs, and the cuts are more precise.

But how exactly does a CNC laser cutting machine work? We go through each of the steps below in detail.

Generating and Amplifying the Beam

The first part of this process is to generate and amplify the laser beam. An important part of this process is the laser resonator, which is made up of extremely reflective dielectric mirrors. These mirrors contain the light of the laser and prevent it from escaping.

The other important part of this process is spontaneous emission, which emits a photo of light; and stimulated emission, which stimulates a high energy photon. Together, spontaneous and stimulated emissions help to generate and amplify the beam as it enters the cutting head of the CNC laser cutting machine. This allows the laser cutting machine to produce a laser beam which is spectrally and spatially concentrated. 

Controlling Intensity by Varying Beam Concentration

Concentrating the beam on a smaller and smaller area increases its intensity, and its ability to generate heat, allowing it to cut through sheetmetal quickly and with high precision. This is exactly what the focusing lens is used for.

The focusing lens enables the CNC laser cutting machine to concentrate the beam onto a specific area of the sheetmetal. This occurs through a process where the beam is guided through the cutting head via the centre of the nozzle, while staying concentrated. Increasing the concentration of the beam on the sheetmetal reduces its overall diameter, which increases its intensity and allows it to cut through the surface with greater precision and speed.

Heating and Cooling in the Laser Cutting Process

As the beam generates high levels of heat by concentrating its light on the sheetmetal, this can also create high levels of heat in both the focusing lens, and the sheetmetal. In order to continue operating for long periods of time, the focusing lens and the sheetmetal must be continuously cooled to prevent them from overheating.

This cooling function is performed by using a variety of different gases, which are released through the machine as the cutting process is occurring. The type of gas used depends on the laser cutting process, which can vary from oxidation cutting, to fusion cutting, and evaporative cutting.

Generally speaking though, the main function of these gasses is to cool and protect the focusing lens, helping to remove the melted residue from the cutting area (the ‘kerf’), and also cool other areas of the sheetmetal to prevent them from unintentional melting.

Moving the Laser Beam

The final part of the process involves moving the beam itself in order to achieve the desired cuts. the movement of the laser beam and the patterns produced are guided through computer numerical control, which is preset by the operator.

There are three main beam movement configurations:

  1. Moving material, which involves moving the sheetmetal while the laser beam remains stationary.
  2. Flying optics, which refers to a laser beam which moves to produce cuts on a stationary piece of sheetmetal.
  3. Hybrid laser cutting, which combines moving both the laser beam and the sheetmetal to achieve a greater level of versatility, efficiency, and precision.

If you would like to know more about CNC laser cutting, or how it could help you to build your ideal metal project, get in touch with us any time via phone or email.

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