Anneal
Applicable materials: ferrous metal (iron, steel) titanium
Laser annealing is a marking technique that uses laser irradiation heat to induce local oxidation without causing significant material ablation, a process that produces indelible permanent black marks without any cracks, dents, or burrs, suitable for surfaces that have already been done, such as surgical instruments and high-precision tool surfaces.
A typical annealing process typically penetrates to a depth of 20 to 30 microns on the surface of the metal to create a stable mark that is not removed by acids, solvents, or abrasive techniques, making it corrosion-resistant.
This dark, permanent marking is ideal for medical device applications where the marking can withstand passivation, salt spray testing, and autoclaving, and does not remove surface material to ensure part integrity and surface quality.
Carve
Applicable materials: metal, thermoplastic materials, paper, wood, organic matter
In laser engraving, the laser beam locally overheats the workpiece material to the vaporization point. In some cases, the thermal effect is very noticeable, with a large heat-affected zone (HAZ) that can produce coloured oxides at the bottom or engraving, further accentuating the marking. Through the melting displacement and/or vaporization of the material, a depression is formed in the workpiece. Typical engraving depths are between 0,001 mm and 0,1 mm, and almost any material can be engraved with a suitable laser source (fiber, YAG, CO2).
Deep engraving is a method of creating durable, straightforward, and anti-counterfeit product markings that are resistant to wear and corrosion, even after paint or coating processes used in automotive applications.
Deep engraving also includes three-dimensional marking, that is, several layers of material are gradually removed at different depths to form a three-dimensional engraving on the workpiece. 3D marking relies on external devices to reposition the focus area to affect different layers along the Z-axis. The typical depth of deep engraving varies between 0,1 mm and 5 mm.
Surface etching
Applicable Material: Metal
The laser etching process involves using laser irradiation to alter the surface finish of a metal and create contrast by enhancing the way it reflects ambient light. The depth of penetration usually does not exceed 0.01 mm. Laser etching is probably the most widely used high-speed laser marking process.
Coating ablation, paint stripping
Applicable Materials: Any material depends on the coating
The ablative marking process involves the partial or complete removal of one or more coatings that expose the contrasting colors of the substrate material. This process is popular for backlit markings and "day and night" buttons and keys in the automotive, computer, and mobile electronics industries. In these industries, a dark coating is sprayed onto a transparent substrate and then selectively ablated by laser irradiation.
The short pulses with high peaks reduce the thermal impact on the material, resulting in high-resolution markings. Laser ablation can also be used to prepare substrates for other steps in the production process. For example, when welding oily, dirty, or oxidized surfaces, or when electrical contact is required on a metal frame. In these applications, the use of cleaning agents and chemicals can be eliminated and replaced with laser ablation.
Foaming
Applicable material: thermoplastic material
Due to the material's laser absorption and low thermal conductivity, the local workpiece temperature rises to the melting point. Small bubbles appear in the melted material, causing it to increase in volume and form a plastic foam. The machining area appears much brighter than the surrounding material. This process is often enhanced with laser marking additives to improve contrast and the reliability of the marking process. The foam marking process is often tactile and has poor scratch resistance.
Discoloration
Applicable material: thermoplastic material
On some thermoplastic materials, "green lasers" (second harmonic laser 532 nm) and "ultraviolet lasers" (third harmonic laser 355 nm) can be used for bleaching and photoreduction labeling processes. This effect is also known as "cold marking" because it reduces the "heat footprint" on the substrate. The use of laser-sensitive additives in plastics can yield considerable advantages, which are great benefits for contrast, speed, and stability in the marking process.
Additives in plastics increase the clarity and contrast of contours, which in turn improves the readability of marked content, such as machine-readable codes. Used with transparent and translucent materials, additives can result in uniform contrast dispersion. Additives in plastics increase the variety of product colors and are critical to the markability of certain materials. Significant for the markability of certain materials.
Carbonization
Applicable Materials:Thermoplastic materials, paper, wood, organic matter
Carbonization of one or more specific pigments, flame retardants, or other additives produces consistent marks with sharp contrast in most light-colored thermoplastic materials. Depending on the evaporation of the material and the level of its absorption, there may be a phenomenon of engraving.
Subsurface Laser Engraving (SSLE)
Suitable materials: glass, transparent materials
Focusing intense laser radiation below the surface of a glass object creates a mark consisting of microcracks caused by locally absorbed laser light. As a result, microscopic cracks can cause multiple internal light reflections, making the spot appear white. 2D and 3D images can be created inside the glass without affecting the polished surface. The image is produced point by point, and the workpiece moves in two or three dimensions. This technology is popular for decoration as well as tamper-proof tracking.
Colored markings on ferrous metal and titanium
Suitable material: ferrous metal (iron, steel) titanium
Laser color marking of stainless steel and titanium is a well-known marking technology, but its popularity in the industry is still limited. Like laser annealing, laser color marking is also based on surface oxidation, and changing different laser parameters will result in different oxide coatings, allowing the user to see different colors.
The most important parameters in laser marking are focal spot diameter, sample power, marking speed, line spacing, marking direction, repetition rate, and pulse length. Thanks to the ability to control the laser pulse width and high stability, MOPA fiber lasers are able to produce uniform and reliable color marking on ferrous metals and titanium.
Black markings on anodized aluminum
Applicable material: anodized aluminum
The so-called "black marking" is a technique widely used by mobile device manufacturers to mark trademarks and serial numbers on anodized aluminum enclosures with high contrast, a pleasant look and feel, and no damage to the protective oxide layer. Due to the ability to operate in short pulses, as well as a high degree of control over energy and peak power, fiber lasers are the best choice for combining a true black appearance with the benefits of laser marking without compromising the corrosive properties of the coating material.
Be the first to comment