Laser marking machines can produce various color effects through interaction with different materials. These effects depend primarily on physical or chemical changes in the material itself, rather than traditional colored inks. The following classifies the color manifestations on different materials.
1. Color Effects on Metal Materials
Stainless Steel
White effect: By adjusting laser parameters such as power, frequency, and pulse width, a fine oxide layer or melting trace is formed on the stainless steel surface. This layer reflects light and appears white.
Black effect: High-temperature laser oxidation creates a black oxide layer, such as Fe₃O₄, producing a permanent black mark.
Yellowing effect: During deep marking, laser energy causes local carbonization or the formation of yellow oxides, presenting dark or yellowish textures.
Whitening effect: By controlling the scanning path and energy density, a shallow melting or oxide layer is created on the metal surface, which reflects light and appears light white.
Color Steel (for MOPA Laser Marking Machines)
Multi-color marking: MOPA lasers, which are fiber lasers with adjustable pulse width, precisely control pulse width and frequency to form oxide layers of different thicknesses or color gradients on color steel. This can produce red, blue, green, and other color effects.
Texture colors: On non-metal coatings or plated surfaces, the laser can engrave a three-dimensional texture that combines with the base material color to create contrast.
2. Color Effects on Non-Metal Materials
Glass (UV Laser Marking Machine)
White or frosted effect: The 355 nm wavelength of a UV laser is absorbed by glass. The marking appears white due to microcracks or changes in refractive index. A frosted texture can also be produced to enhance decorative appeal.
Plastics (UV Laser Marking Machine)
Black effect: Plastics containing carbon additives, such as ABS and PC, carbonize under laser irradiation and form black marks.
Gray-white or light white effect: Carbon-free plastics like PP and PE produce light traces through thermal decomposition or surface melting.
3. Principles and Limitations of Color Formation
The color effects produced by laser marking come from physical or chemical changes such as oxidation, carbonization, melting, or refractive index changes. No pigment is added. The result is highly material-dependent, since different materials absorb laser wavelengths differently. For example, stainless steel oxidizes easily and shows color, while plastics generally require carbon content to produce black marks. Laser marking cannot directly output traditional printing colors such as red or yellow, and the color range is limited by the properties of the material.
4. Typical Machine Types and Color Applications
Fiber laser marking machines are mainly used for metal marking, producing black, white, yellowing, and whitening effects on stainless steel, aluminum alloys, and similar metals.
MOPA laser marking machines are designed for multi-color marking on color steel and texture engraving on non-metals, offering high flexibility.
UV laser marking machines focus on glass and plastics, featuring white, frosted, and light color effects. They are widely used in precision electronics, daily necessities, and other fields.
In summary, the color effects of laser marking machines can be divided into three categories: metal oxidation colors such as white, black, and yellow; non-metal carbonization or melting colors such as black and gray-white; and special texture colors such as frosted and gradient effects. The core advantages are non-contact processing, high precision, and permanent marking. However, the available color range depends on the material and the machine type, and laser marking cannot fully replace the color functions of traditional printing.
For non-standard components used in these laser systems, such as optical mounting brackets, rotary axis adapters, and precision guide rails, Hansheng Automation provides custom machining based on customer drawings or samples, including single-piece and small-batch orders.
