Understanding Laser Cleaning

Each cleaning job presents its own unique conditions. It is essential that you take the time to fully understand how to operate your fiber laser cleaning machine properly in various scenarios. Learning how the machine responds to different settings and surfaces is critical.

There are no universal or “one-size-fits-all” settings—adjustments often need to be made on the fly. If you're unable or unwilling to make these adjustments confidently, we strongly advise against testing the machine for client work, as improper use can lead to damage.

Every job will require a customized setup. While these machines are technically plug-and-play, safe and effective operation still demands knowledge, attention, and hands-on experience—since different materials and coatings respond uniquely to the laser.

_______________


🔍 The “Low and Slow” Principle in Laser Cleaning

When using a fiber laser cleaning machine, following the “low and slow” approach is essential for safe, effective, and damage-free results. This principle helps protect the substrate while optimizing cleaning performance, especially when working with delicate or unfamiliar materials.

 

🔹 What “Low” Means: Start with Minimum Laser Settings

  • Low Power: Begin with the lowest laser power setting that might affect the contaminant. Avoid starting with full power, which can damage the surface.
  • Low Frequency (if adjustable): Higher frequencies can clean faster but may also generate more heat. Start with a lower or moderate frequency, especially on sensitive materials.
  • Short Pulse Duration: For pulsed lasers, use shorter pulse durations (e.g., nanoseconds) to minimize heat transfer and focus energy on surface contaminants only.

 

🔹 What “Slow” Means: Controlled Movement of the Laser

  • Slow Scan Speed: Move the laser beam—or the workpiece—slowly across the surface. This increases the pulse overlap and improves cleaning efficiency.
    Multiple Passes: Don’t aim to clean in a single pass. Make several slow, controlled passes to remove contaminants gradually and safely.

 

✅ Why “Low and Slow” is the Best Starting Point

  1. Protects the Substrate:
     Excess energy or fast passes can damage the material. Risks include:
    • Discoloration
    • Pitting or etching
    • Warping from heat
    • Loss of surface finish or structural integrity

 

2. Improves Cleaning Precision:

Starting low and adjusting gradually helps you identify the ideal settings that clean effectively without harming the surface.

  1. Controls Heat Buildup:
     Slower operation allows heat to dissipate, reducing the chance of thermal damage.
    Minimizes Fume Output:
  2. Excessive energy creates more fumes. Low and slow operation improves air quality and the performance of fume extraction systems.
  3. Reduces Rework and Cost:
     Damaging parts means wasted time and money. A careful approach prevents rework and scrapping of valuable items.
  4. Supports Learning and Documentation:
     Every material and contaminant behave differently. By starting low and slow, you can fine-tune your process and record effective settings (power, frequency, speed, spot size, etc.) for future jobs.

 

 

🧪 Best Practices When Applying “Low and Slow”

  • Start with a test patch on a non-critical area or scrap piece of the same material.
  • Adjust one parameter at a time—increase power, speed, or frequency incrementally and observe the effect.
  • Inspect visually for signs of damage, discoloration, or incomplete cleaning.
  • Listen to the sound: a clean “pop” often indicates effective ablation, while a harsh or aggressive sound may mean you’re burning into the base material.

 

💡 Think of it like peeling an onion—layer by layer.

Your goal is to gently remove only the unwanted layer of contamination without damaging the surface beneath. Laser cleaning is a precision process, not a race.

 

____________________

 

🔧 Understanding Key Parameters for Pulsed Laser Cleaning

When using a pulsed fiber laser for cleaning applications—such as varnish removal on wood—each setting plays a critical role in balancing cleaning efficiency with surface protection. Below is a breakdown of the main parameters and how they work together:

1. Laser Power: 300W

  • Definition: Represents the average output power of the laser over time.

Function: Higher power increases cleaning speed and efficiency. A 300W laser delivers sufficient energy to rapidly ablate varnish coatings by vaporizing or decomposing the material without prolonged exposure.

2. Frequency: 165 kHz

  • Definition: The number of laser pulses emitted per second (165,000 pulses/sec).
  • Function: Higher frequency means more laser hits per second, accelerating the cleaning process. However, it must be balanced to avoid heat buildup. Combined with a short pulse width, high frequency enables fast, precise ablation while minimizing substrate heating.

3. Pulse Width: 500 ns

  • Definition: Duration of each laser pulse (500 nanoseconds = 0.0000005 seconds).
  • Function: Short pulses concentrate energy in brief bursts, creating a clean "cold ablation" effect. For organic coatings like varnish, this prevents excessive heat transfer and protects wood from charring or etching.

4. Scan Speed: 15,000 mm/s

 

  • Definition: The rate at which the laser beam moves across the surface.
  • Function: High scan speed improves cleaning efficiency by covering large areas quickly. It must be carefully balanced with frequency and pulse width to ensure enough pulses overlap for complete cleaning without leaving streaks or overheating any one spot.

5. Scan Spacing: 200 µm

  • Definition: Distance between adjacent scan lines. 
  • Function: Controls beam overlap to ensure even coverage. 200µm spacing typically allows partial overlap of the laser spot, improving uniformity without over-processing. Too much spacing can cause uncleaned gaps; too little may lead to overexposure.

6. Scan Length: 25 mm

  • Definition: The linear distance the laser travels in one scanning segment.
  • Function: Defines the working area per pass. For large surfaces, the machine performs multiple overlapping 25mm strokes to clean the entire area evenly.

7. Scan Pattern: Flower

  • Definition: A complex, non-linear beam path that mimics petal-shaped movements.
  • Function: Promotes even energy distribution. Reduces hot spots and minimizes heat buildup, especially on sensitive materials like wood. Helps avoid charring by varying dwell time across the surface, leading to smoother, more uniform cleaning results.

✅ Summary

  • This specific configuration—300W power, 165kHz frequency, 500ns pulse width, 15,000 mm/s scan speed, 200 µm spacing, 25 mm scan length, and a flower pattern—is optimized for precise varnish removal with minimal thermal damage. It allows efficient material ablation while preserving the surface integrity of heat-sensitive substrates like wood.
  • Using the correct combination of settings ensures effective cleaning, extended equipment life, and consistent quality results. Always conduct tests and adjust parameters as needed based on surface condition and coating thickness.