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Laser Marking Application Case: Black Marking on Stainless Steel

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2026-07-13

Laser Marking Application Case: Black Marking on Stainless Steel

Equipment Configuration: Chuangxin MFP-50W Fiber Laser

Black marking on stainless steel is one of the most commercially valuable applications in laser marking—it creates deep black, high-contrast marks on stainless steel surfaces with a visual effect far superior to standard gray-white marking. It is widely used for high-end product appearance identification, brand logos, precision instrument panels, and similar applications.

I. Black Marking Principle

The essence of black marking on stainless steel is laser-induced oxidation: the laser heats the stainless steel surface, forming a thick, dense oxide layer (primarily Fe₃O₄). This oxide layer effectively absorbs visible light, resulting in a deep black appearance.

Key control factors:

  • Low frequency (20-30 kHz): High single-pulse energy, strong penetration, conducive to forming a thick oxide layer
  • Slow speed (100-300 mm/s): Longer laser dwell time per unit area, sufficient heat accumulation
  • Moderate hatch density: Ensures a uniform and continuous oxide layer

II. Equipment Configuration

Item Parameter
Laser Source Chuangxin MFP-50W Acousto-Optic Q-Switched Pulsed Fiber Laser
Wavelength 1064nm
Repetition Rate Range 45-170 kHz (low frequency recommended for black marking)
Pulse Width ~100ns
Cooling Method Air-cooled

The 50W model is one of the best power levels for black marking—sufficient energy to form a thick oxide layer without burning or peeling the oxide layer due to excessive power.

III. Parameter Reference

Recommended Starting Parameters

Parameter Recommended Value Notes
Power 50-75% Black marking requires higher energy input
Speed 100-300 mm/s Slow speed is key; do not go too fast
Frequency 20-30 kHz Low frequency increases single-pulse energy
Hatch Spacing 0.03-0.06mm Too dense causes over-burning, too sparse shows striations
Fill Method Unidirectional fill Unidirectional fill produces a denser oxide layer
Number of Passes 1-2 2 passes can deepen blackness, but avoid over-burning
Focal Position 0 (on focus) On focus provides the most concentrated energy

Parameter Tuning Approach

  1. Blackness not deep enough → Reduce speed or increase power (adjust by 10% each time)
  2. Yellow/brown edges → Oxide layer temperature insufficient, reduce speed or increase power
  3. Surface ablation, peeling → Energy too high, reduce power or increase speed
  4. Uneven blackness → Check focal accuracy, or switch to denser hatch spacing

    5. IV. Effect Characteristics

    • Color: Pure black to deep black, matte texture
    • Contrast: Extremely high, forming a sharp contrast with the stainless steel substrate
    • Feel: Slight tactile sensation, oxide layer fused with the substrate
    • Wear Resistance: Excellent, oxide layer firmly bonded to the substrate, not easily detached
    • Corrosion Resistance: The oxide layer provides protection, passes salt spray testing

    V. Differences from Standard Marking

    Comparison Standard Marking Black Marking
    Color Light gray to dark gray Pure black to deep black
    Speed 600-1500 mm/s 100-300 mm/s
    Frequency 30-50 kHz 20-30 kHz
    Time per Piece Short Long (approximately 3-5 times longer)
    Visual Effect Standard High-end, refined

    VI. Precautions

    1. Material grade has a significant impact: 304 stainless steel produces the best black marking results. 316 stainless steel contains molybdenum, making oxide layer formation more difficult; it may require slower speeds or higher power
    2. Surface preparation: Thorough cleaning is essential before black marking; oil and fingerprints can cause uneven blackness or spots
    3. Batch consistency: Material batch variations in production may affect blackness; inspect the first piece of each batch
    4. Thin sheet caution: Black marking on thin sheets below 0.5mm accumulates significant heat and is prone to deformation; consider adding heat dissipation or reducing power

      5. VII. Application Scenarios

      • High-end kitchenware brand logos
      • Medical device handle identification
      • Precision instrument panel scales
      • Stainless steel medals / souvenirs
      • Automotive interior decorative marks
      • Food equipment nameplates

      Summary: Black marking on stainless steel is a premium effect achieved with a 50W fiber laser. The key lies in “slow speed + low frequency”—there is no rushing it. Although it is slower than standard marking, the visual texture and product grade are entirely different, making it an excellent way to add value to products.

      *Actual results are affected by material grade and surface condition. It is recommended to confirm through sample testing before batch production.*

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