Cutting quality defines the true performance of a fiber laser cutter. It’s not just about speed-it’s about precision, consistency, and clean results. In this guide, we’ll break down the five most important criteria to evaluate cutting quality and share practical tips to achieve premium results with your CNC fiber laser cutting machine.
I. Smoothness of the Cut Surface
Smoothness of the cut surface is one of the most critical indicators of fiber laser cutting quality. A high-quality cut should leave a smooth, uniform edge that requires little to no post-processing. In fact, surface smoothness is often the first thing customers notice when evaluating product quality.
Why rough surfaces happen:
- Excessive Power: Excessive power can melt too much material, leaving an uneven texture.
- Incorrect Focus Position: If the laser beam isn’t sharply focused, the cut line widens, creating jagged textures.
- Slow Speed: When cutting too slowly, excess heat accumulates, damaging the surface finish.
- Material Differences: Stainless steel and carbon steel cut cleanly, but reflective metals like copper and brass often leave rougher finishes.
- Assist Gas Effect: Oxygen tends to create smoother cuts on mild steel compared to compressed air.
Improvement strategies:
- Use optimized laser power according to material thickness.
- Check auto-focus or manually fine-tune focus for different sheet metals.
- Slightly increase speed to reduce overheating.
- Choose the right gas–oxygen for carbon steel, nitrogen for stainless steel, and high-pressure air for aluminum.
A smoother cut means fewer polishing steps afterward, saving both time and labor.
II. Burrs on the Cut Edges
Burrs are small raised edges or molten particles sticking to the bottom of the workpiece. While sometimes unavoidable, excessive burrs reduce part quality and add cost due to extra grinding or deburring.
Why burrs appear:
- Wrong parameters: Slow speed or high power causes incomplete separation.
- Low gas pressure: If the assist gas cannot blow away molten slag, it solidifies on the edge.
- Material thickness: Thicker plates tend to accumulate more burrs.
- Heat overload: Too much heat causes uneven solidification.
How to minimize burrs:
- Fine-tune speed and power so the laser cuts cleanly without excessive melt.
- Increase gas pressure or use high-purity nitrogen for stainless steel to avoid oxidation.
- For mild steel, oxygen at the right pressure ensures cleaner edges.
- If burrs still occur, apply mechanical deburring tools or sanding belts.
Less burrs means better appearance, reduced secondary work, and higher efficiency in mass production.
III. Cutting Gap (Kerf Width)
Cutting Gap, also known as kerf width, refers to the width of material removed by the laser beam. Maintaining a consistent kerf is crucial in industries like aerospace, automotive, and sheet-metal fabrication where parts must fit precisely.
Problems caused by poor kerf control:
- Loose fittings: If the kerf is too wide, assembled parts won’t fit tightly.
- Material waste: Wide kerfs reduce yield per sheet.
- Poor aesthetics: Irregular kerf width look unprofessional.
Reasons for inconsistent kerf:
- Misaligned or unfocused laser beam.
- Excessive power causing over-burning.
- Wrong gas pressure blowing molten metal too far.
Optimization tips:
- Regularly calibrate focus to maintain beam sharpness.
- Adjust power levels for different thickness.
- Balance gas flow-too high increases kerf width, too low leaves slag.
A controlled, narrow kerf not only improves assembly accuracy but also increases material utilization, lowering overall costs.
IV. Verticality of the Cut (Perpendicularity)
Verticality of the cut, also known as perpendicularity, describes how straight the cut edge is relative to the material surface. While s slightly tilted cut may be acceptable for decorative applications, in mechanical assemblies vertical cuts are essential for accuracy and reliability.
Why perpendicularity issues happen:
- Cutting head misalignment: The beam enters at an angle, creating slanted edges.
- Imbalanced speed-power settings: Too much heat causes edges to taper.
- Material thickness: The thicker the plate, the more difficult it is to maintain perfect verticality.
How to ensure vertical cuts:
- Regularly check and align the cutting head.
- Adjust speed and power-too slow or too hot causes edge tapering.
- Select the right assist gas to keep molten metal from pulling the cut sideways.
For precision industries like automotive or machinery manufacturing, perpendicular cuts are critical for assembly accuracy.
V. Heat-Affected Zone (HAZ)
The heat-affected zone is the portion of material around the cut that is thermally altered but not melted. A large HAZ can cause discoloration, structural weakness, or warping.
Why HAZ occurs:
- Too much laser power concentrates excessive heat.
- Cutting too slowly allows heat to spread.
- Thick plates require high energy, enlarging the HAZ.
How to reduce HAZ:
- Increase cutting speed while lowering power.
- Use nitrogen for stainless steel to reduce oxidation and discoloration.
- Implement cooling strategies or allow natural cooling after cutting.
Smaller HAZ means the base material retains its original mechanical properties, which is especially important in industries requiring strength and durability.
VI. How to Achieve the Best Fiber Laser Cutting Quality
While the overall machine quality of a fiber laser cutting machine is crucial, it is the parameters settings and maintenance practices that ultimately decide the cutting results. Even the most advanced CNC fiber laser cutting machine requires proper setup and calibration to consistently deliver premium results. Here are five detailed strategies:
- Set Laser Power Properly
The laser power must always match the material type and thickness. Too much power can over-burn and create a wide kerf, while too little power may result in incomplete cuts.
- For thin stainless steel or aluminum, lower power with high speed works best.
- For thicker carbon steel plates, high power combined with oxygen assist gas ensures deep, clean cuts.
- Always test on scrap pieces before mass production to confirm the ideal power setting.
- Control Cutting Speed
Cutting speed directly affects smoothness, burr formation, and heat-affected zone (HAZ).
- Cutting too slowly allows heat to build up, causing discoloration and rough edges.
- Cutting too fast may leave incomplete separations or dross.
- A good practice is to gradually increase speed until the cut edge remains smooth with minimal slag.
- Adjust Gas Pressure and Type
Assist gas not only blows away molten metal but also influences edge quality and oxidation.
- Oxygen: Ideal for cutting carbon steel, providing fast cutting with a slight oxidized edge.
- Nitrogen: Best for stainless steel and aluminum, leaving bright, oxide-free edges.
- Compressed Air: A cost-effective option for thin sheets, especially aluminum.
- Ensure gas pressure is neither too low (causing burrs) nor too high (widening kerf width).
- Maintain Focus and Alignment
Laser focus determines how concentrated the energy is on the workpiece. A slight misalignment can reduce accuracy.
- Use an auto-focus cutting head for materials of varying thickness.
- Regularly calibrate optics to maintain consistent cutting performance.
- Check the cutting head alignment to avoid tilted cuts or uneven kerf width.
- Perform Routine Maintenance
Stable machine performance relies heavily on daily and weekly maintenance.
- Keep the lens, nozzle, and protective glass clean to avoid power loss.
- Inspect mirrors and optical paths for dust or residue.
- Replace worn nozzles promptly to ensure gas flow stability.
- Maintain the cooling system and check assist gas filters to prevent contamination.
VII. Why Choose SENFNEG Laser?
However, even the best cutting parameters won’t help if the machine itself lacks stability or precision. That’s where SENFENG laser comes in.
- Advanced fiber laser cutting machine designed for high precision and long-term durability.
- Flexible configurations for cutting, welding, cladding, and bending-meeting multiple production needs.
- Global service network ensuring timely support and training.
- Innovative technology like auto-focus cutting heads, intelligent monitoring, and energy-efficient designs.
Whether you are in sheet-metal processing, automotive, furniture, or heavy machinery manufacturing, SENFENG USA provides reliable solutions to guarantee cutting quality and production efficiency.
Ready to upgrade your fabrication process? Contact SENFENG USA today to discover how our fiber laser cutting machines deliver stable performance and premium results.
