Four aspects: the quality of laser cutting is judged

Mastering the principles behind different process factors in laser cutting machines is crucial for enhancing the quality of the machined surface. By understanding these factors, we can adopt effective strategies to improve surface quality and achieve better results. For most applications involving laser cutting processes, the quality of the outcome typically involves several key aspects:

1. A smooth cutting surface with minimal roughness and no brittle fractures.

When a laser cuts through a sheet at high temperatures, the molten material traces often do not appear directly beneath the laser beam but are expelled at the rear of the beam. This can create wavy lines along the cutting edge, following the movement of the laser. To address this issue, reducing the feed rate towards the end of the cutting process significantly minimizes the formation of such lines.

2. Narrow kerf width (primarily dependent on the laser beam's spot size and the quality of the laser tube).

While the kerf width generally doesn’t impact overall cutting quality, it becomes critical when creating highly precise internal contours. The kerf width determines the smallest possible internal diameter of the profile. As the sheet thickness increases, so does the kerf width. To maintain consistent high precision, regardless of kerf width variations, the workpiece should remain within the optimal processing area of the laser cutting machine.

3. High kerf perpendicularity with minimal heat-affected zones.

When processing materials thicker than 18 mm, the perpendicularity of the cutting edge becomes extremely significant. If the laser beam moves away from the focal point, it diverges, leading to wider cuts either at the top or bottom of the material depending on the focus position. A cutting edge just a few hundredths of a millimeter off the vertical line indicates higher cutting quality.

4. Minimal thermal impact on the cutting material.

As a thermal cutting tool, laser cutting inevitably generates a thermal impact on the material. This impact manifests in three primary ways: a) heat-affected zones; b) depressions and corrosion; c) material deformation. The heat-affected zone refers to the area surrounding the kerf where the material undergoes structural changes, such as hardening. The heat-affected zone reflects internal structural alterations due to high temperatures. Depressions and corrosion negatively affect the cutting edge’s surface, impacting the laser cutting machine’s appearance and causing cutting errors that should be avoided. Lastly, excessive heating during cutting can lead to part deformation, particularly problematic in fine machining where contours and tabs are often just a few tenths of a millimeter wide. Controlling laser power and employing short laser pulses can reduce component heating and prevent distortion.