When processing thick plates with laser cutting machines, many operators encounter a common problem: slag residue after piercing severely affects subsequent cutting quality, leading to rough surfaces, slag buildup, and even nozzle damage. This article will systematically analyze the causes of this problem and provide an efficient solution.

Root Cause: Why Does Piercing Thick Plates Produce Slag?

The core reason for stubborn slag residue after piercing thick plates lies in the fact that, at the moment of piercing, the high-energy molten metal is not completely blown away from the bottom of the plate by the assist gas. The main reasons include:

Parameter Mismatch: Improper settings for piercing power, time, or gas pressure result in insufficient energy for complete piercing or excessive melting and accumulation.

Process Sequence Issues: Directly switching to cutting after piercing without allowing sufficient time for slag removal.

Material and Gas Factors: Rust or coating on the plate surface, or insufficient oxygen purity (when using oxygen cutting), reduces reaction efficiency.

Inaccurate Focal Point Position: The focal point is not adjusted to the optimal position for piercing thick plates, resulting in insufficient energy density.

Systematic Solution: Say Goodbye to Piercing Residue

To solve this problem, targeted optimization of the laser cutting machine's process parameters and operating procedures is necessary:

Optimize Piercing Parameters and Process

Adopt Progressive Piercing: Avoid using excessively high power for a single penetration. Set a stepped power from low to high, combined with a pulse mode, to allow the material to melt layer by layer, facilitating gas purging.

Increase Piercing Delay: After piercing, set a short delay (0.5-1.5 seconds) to allow auxiliary gas to continuously purge and thoroughly remove slag from the hole before cutting.

Try the "Double Piercing" Process: For extremely thick plates, perform two progressive piercings at the same location to ensure complete penetration.

Adjust Gas and Focus Settings

Ensure Gas Pressure and Purity: During the piercing stage, the gas pressure can be appropriately increased (especially when using nitrogen cutting), and the gas source must be pure and dry. When using oxygen cutting, high-purity oxygen is crucial.

Correcting the focus position: For piercing thick plates, the focus can be slightly lowered to about 1/3 of the plate thickness to expand the bottom molten pool and facilitate slag removal.

Pay attention to daily maintenance and material handling

Cleaning the plate surface: Clean rust, oil, and coatings from the plate surface before cutting.

Regularly maintain the cutting head: Ensure the nozzle is clean, undamaged, and maintains the correct distance from the plate to ensure stable airflow.

In summary, solving the problem of slag residue during thick plate piercing in laser cutting machines hinges on understanding piercing dynamics and finely adjusting process parameters (power, time, gas, focus), coupled with a reasonable piercing process and good equipment maintenance. Implementing the above solutions can significantly improve piercing quality, ensure a smooth and flat cut surface, and ultimately improve production efficiency and processing quality. If the above does not solve your problem, please contact a RITMAN Laser after-sales engineer for assistance.