1. Incorrect Focus Position
The laser focus must be precisely aligned with the material surface or the optimal depth within the material.
If the focus is too high, the lower part of the material may not receive enough energy.
If the focus is too low, the upper surface may over-melt while the beam fails to cut through the bottom.
2. Insufficient Laser Power
The laser must provide enough energy density to fully melt or vaporize the material.
Power set too low, laser aging, or output decay can result in incomplete penetration.
For thicker or highly reflective materials like aluminum or copper, higher power is often required.
3. Contaminated or Damaged Optics
Laser energy passes through lenses and protective mirrors.
Dust, smoke, or oil contamination can reduce transmission efficiency.
A dirty or damaged protective lens weakens the beam, making it difficult to cut through.
4. Inadequate or Unstable Assist Gas Pressure
Assist gas (oxygen, nitrogen, or air) plays a crucial role in removing molten material.
If pressure is too low, molten residue may accumulate at the bottom of the cut.
Unstable gas flow can also affect cut consistency and lead to incomplete penetration.
5. Cutting Speed Too Fast
If the material feed rate is too fast, the laser does not have enough time to act on the material.
This results in partial cutting, especially on thick plates.
Adjusting to a slower speed allows the beam to fully penetrate.
6. Material-Related Issues
Some materials pose inherent challenges:
High reflectivity (aluminum, copper) can reduce effective absorption of the laser.
Excessive thickness may exceed the laser's cutting capacity.
Coatings, rust, or impurities can scatter or absorb energy unevenly.
Conclusion
Incomplete penetration in laser cutting usually relates to focus position, power stability, optical condition, assist gas, cutting speed, or material characteristics. By systematically checking these factors-starting with focus calibration and power output, followed by optics, gas supply, and speed-operators can quickly identify the cause and restore stable cutting performance.
-- Rayther Laser Lyra Zhang
https://www.raytherlasercutter.com/laser-cutting-machine/fiber-laser-cutting-machine.html