1.The impact of focus on laser cutting

The focus is the smallest spot of the laser beam behind the focusing lens, which determines the energy distribution and power density of the laser beam. In the laser cutting process, the position of the focus has an important impact on the cutting quality.
Relationship between focus position and cutting depth
The focus position is closely related to the cutting depth. When the focus is on the surface of the material, the energy distribution of the laser beam is the most concentrated, the power density is the highest, and the cutting depth is the largest. As the focus moves toward the inside of the material, the energy distribution of the laser beam gradually spreads, the power density decreases, and the cutting depth decreases.
Relationship between focus position and cutting speed
The focus position also has a certain impact on the cutting speed. When the focus is on the material surface, cutting speed is fastest due to the highest power density. As the focus moves into the material, the power density decreases and the cutting speed slows down.
The relationship between focus position and cutting quality
Focus position has a significant impact on cut quality. When the focus is on the material surface, the cutting edge is smooth and burr-free, but a larger heat-affected area may be produced. As the focus moves toward the interior of the material, the cut edge may become rougher, but the heat-affected zone decreases.

2. Focus adjustment for plates with different thicknesses

Thin plate cutting
For thin sheet cutting, the focus is usually at or just below the surface of the material. This ensures cutting speed and quality. Due to the good thermal conductivity of the thin plate, the focus position has less impact on the heat affected area.
Medium thickness plate cutting
For medium thickness plates, the focus position needs to be adjusted according to the thickness and material of the plate. Generally speaking, the focus is located on the surface of the material or slightly below it to ensure cutting speed and quality. For some high-reflectivity materials, such as copper, aluminum, etc., the focus may need to be appropriately lowered to reduce reflection damage to the laser.
Thick plate cutting
For thick plate cutting, the focus usually needs to be inside the material. This ensures cutting depth while reducing the heat-affected zone. The specific position of the focus needs to be adjusted according to the thickness and material of the plate and the power of the laser.

3. Focus adjustment method

Manual adjustment
Manual focus adjustment is to change the focus position by adjusting the position of the laser head. This method is simple and easy to implement, but the adjustment accuracy is low, and it is suitable for preliminary debugging and simple cutting tasks.
auto-adjust
Automatic focus adjustment is to automatically adjust the position of the laser head through the control system of the laser cutting system to achieve precise focus control. This method is suitable for high-precision cutting tasks and can greatly improve cutting quality and efficiency.
focus monitoring
Focus monitoring monitors the focus position in real time through a sensor installed on the laser head, and feeds the data back to the control system to achieve precise focus control. This method is suitable for high-precision, high-speed cutting tasks.