One of the most common quality issues in fiber laser cutting is dross buildup on the bottom edge of the cut. This unwanted residue both mars the visual quality of the part and creates a need for additional cleaning in subsequent processes. In this article, we look at the causes of dross formation and how to prevent it.
What Is Dross?
Dross is metal residue that solidifies and accumulates on the bottom edge of a part when molten material isn't fully removed from the cut line during laser cutting. This residue is typically hard and adheres to the cut edge, requiring additional labor to remove mechanically.
Factors That Cause Dross Formation
Insufficient Gas Pressure
Applying assist gas (oxygen or nitrogen) at a pressure too low to fully remove molten material from the cut line is one of the most common causes of dross formation. Pressure should be set appropriately for material thickness.
Incorrect Cutting Speed
When cutting speed is too high, there isn't enough time to fully remove molten material, and dross accumulates on the bottom edge. When speed is too low, a different type of dross can form due to excessive heat buildup.
Focal Point Setting
Incorrect positioning of the laser beam's focal point relative to material thickness causes uneven energy distribution along the cut line, increasing dross risk.
Nozzle Condition and Distance
A worn or dirty nozzle can cause irregular gas flow, triggering dross formation. Additionally, failing to keep the distance between the nozzle and material constant leads to inconsistent results along the cut.
Dross Risk by Material Type
Materials like stainless steel and aluminum are more prone to dross formation than carbon steel; nitrogen gas is typically used for these materials, reducing both oxidation and dross risk together. In carbon steel, when oxygen cutting is used, dross formation can be largely controlled with the right parameters.
Practical Approaches to Preventing Dross
- Determining the optimal gas pressure and speed combination through test cuts specific to material thickness
- Regularly checking nozzle condition and replacing it when necessary
- Periodically readjusting the focal point according to material thickness
- Keeping the cutting table clean to prevent reflected heat from affecting cut quality
The Impact of Dross on the Production Process
Parts with dross require an additional cleaning step after cutting, which both extends labor time and can create additional risk of surface damage. Especially for parts intended for visible surfaces, preventing dross from the start eliminates additional cost and time loss.
DMK Makina's Approach to Preventing Dross
Using parameter experience accumulated across different material types and thicknesses, DMK Makina optimizes gas pressure, cutting speed, and focal point settings to keep dross formation to a minimum. With regular nozzle maintenance and quality control processes, the company delivers clean cut edges that require no additional processing.
Serving manufacturers across the Thrace and Marmara regions, DMK Makina delivers high-quality, clean laser cutting, evaluating each project's material and thickness requirements together with its technical team.