Laser Marking Application Case: Black Marking on Aluminum
Laser Marking Application Case: Black Marking on Aluminum
Equipment Configuration: Chuangxin MFP-50W Fiber Laser
Black marking on aluminum is a “conditional” application—bare aluminum cannot naturally produce pure black marks, because aluminum has high reflectivity and its oxide layer formation mechanism differs from stainless steel. The aluminum material that truly can achieve black marking is anodized aluminum. This case explains the differences between the two and the respective methods.
I. Black Marking Principle
Black Marking on Anodized Aluminum
Anodized aluminum has a dense artificial oxide film (Al₂O₃) on its surface. The laser removes this oxide layer to reveal the natural aluminum color (silver-white), achieving a high-contrast “black-and-white reversal” effect. Strictly speaking, this is not “black marking”—it is revealing the silver-white substrate, forming white marks on the dark anodized layer.
Black Marking on Bare Aluminum
Bare aluminum cannot naturally form a black oxide layer. If black marks on bare aluminum are needed, there are two solutions:
- Marking spray (Cermark, etc.): After spraying, the laser fuses the spray material onto the aluminum surface, forming a black mark
- MOPA laser dark treatment: Using a MOPA with certain parameters can produce dark gray marks, but not true black
- Effect: Bright white marks; the darker the anodized layer color, the higher the contrast
- Feel: Smooth, almost no tactile sensation
- Wear Resistance: Good, the exposed aluminum substrate in the marked area will also naturally oxidize to form a protective layer
- Effect: Deep black marks, matte texture
- Feel: Slight protrusion (fused spray layer)
- Wear Resistance: Fairly good, but not as durable as the anodized aluminum solution
- “Misconception” about anodized aluminum black marking: Many customers think that black marking on anodized aluminum produces black marks, but it actually produces white marks. This needs to be clearly communicated to the customer in advance
- Anodized layer thickness effect: The thicker the anodized layer, the brighter the white marks; excessively thin anodized layers (<5μm) may be completely penetrated by the laser, exposing the gray aluminum substrate
- Limitations of bare aluminum black marking: Without marking spray, only dark gray can be achieved on bare aluminum, not true black
- Spray cost: Marking spray increases per-piece cost and requires spraying, drying, marking, and cleaning steps, making it less efficient than direct marking
- MOPA advantage: If a MOPA laser is used, richer color effects (not just white) can be achieved on anodized aluminum
- 3C electronics product enclosures (anodized aluminum)
- Mobile phone / tablet back cover identification
- Automotive interior aluminum parts
- High-end aluminum gifts
- Aluminum alloy door and window fittings
- Industrial aluminum profile labels
II. Equipment Configuration
| Item | Parameter |
| Laser Source | Chuangxin MFP-50W Acousto-Optic Q-Switched Pulsed Fiber Laser |
| Wavelength | 1064nm |
| Cooling Method | Air-cooled |
III. Parameter Reference
Anodized Aluminum “Black Marking” (Actually White Marks)
| Parameter | Recommended Value | Notes |
| Power | 25-40% | Anodized aluminum does not require high power |
| Speed | 1000-2000 mm/s | High speed ensures only the oxide layer is removed |
| Frequency | 50-80 kHz | High frequency makes marks more uniform |
| Hatch Spacing | 0.03-0.05mm | Moderate is sufficient |
| Number of Passes | 1 | One pass to completion; do not repeat |
| Focal Position | +0.1~+0.2mm | Slight defocus for more uniform marks |
Bare Aluminum + Marking Spray Solution
| Parameter | Recommended Value |
| Power | 50-70% |
| Speed | 300-600 mm/s |
| Frequency | 25-40 kHz |
| Hatch Spacing | 0.03-0.05mm |
| Number of Passes | 1 |
IV. Effect Characteristics
Anodized Aluminum
Bare Aluminum + Marking Spray
V. Precautions
VI. Application Scenarios
Summary: “Black marking” on aluminum needs to be clearly distinguished—anodized aluminum produces white marks (reversed on the dark anodized layer), while bare aluminum requires spray to produce black marks. The 50W power is sufficient, and the anodized aluminum solution has a wide parameter window that is easy to get started with. If the customer wants true black aluminum marks, the anodized aluminum + laser layer removal method, or marking spray, is recommended.
*The color and thickness of anodized aluminum directly affect the marking result. It is recommended to create samples for confirmation before batch production.*
