Laser Etching: Everything You need to Know
What is laser etching?
1. Working principle of laser etching
In the evolution process of engravers, we generally distinguish between laser etching and laser engraving. Understanding simple theoretical principles may play an intrinsic role in our better completion of the carving process. To put it simply, laser etching is a surface marking process. Through the contact between the laser beam and the material surface, only the workpiece surface is melted, forming a clear contrast in texture. The laser beam must provide high energy that can melt the outside. The result is a black, white, or gray marker. It is famous for its versatility in metal and glass applications. From the birth of the first continuous laser beam in 1960 to the invention of the CO2 laser four years later, the laser etching technology has gradually been used for laser welding, laser cutting and other applications. Now, laser etching has been used in automobile, aerospace, electronics, military and other industries. It is most widely used in manufacturing, etching serial numbers and barcodes on various parts and sub assemblies of automobiles, aircraft, medical equipment, etc.
2. Is laser etching permanent?
Laser etching will produce permanent marks, but you can remove the laser etching marks on the material. This is because laser etching does not penetrate the material as deeply as laser engraving. Since the marks produced by laser etching are not too deep in the material, you can easily remove them with sandpaper. The etching trace can be removed to a large extent by polishing and other methods. The non-contact nature of laser etching allows permanent marking on the material surface without causing any undesirable mechanical stress in the material. In addition, laser etching minimizes the risk of unwanted chemical reactions in the material, because no or only minimal chemical contact will darken the etching.
3. Differences between laser etching, laser marking and laser engraving
- Differences between laser etching and laser marking
Laser marking is the process of forming marks on the surface of materials. Although this sounds like laser etching, there is a big difference between the two. In laser marking, the material will not melt or evaporate. Instead, the laser heats the surface, causing the material to stain due to oxidation. In contrast, laser etching involves melting and/or evaporating the top layer of the material to produce voids or micro bumps that highlight the desired shape or pattern.
- Differences between Laser Etching and Laser Engraving
Laser etching is faster, but laser engraving is more durable. This is because the energy required to reach the melting point of the material (laser etching) is less than that required to evaporate the material (laser engraving). Deep laser engraving may even require multiple laser scans, and inevitably takes longer. You can etch glass with a laser. The glass is laser etched with the Monport 40W CO2 laser to obtain a gray white effect and enhance the contrast of the design. In addition, laser etching of glass is preferable to laser engraving because it is a fragile material, and making deep grooves will weaken the glass.
Different cutting depths:
One obvious difference is the cutting depth, which plays an important role in the visibility and wear resistance of the mark. The cutting depth depends on the hardness of the material and the rated power of the laser mark. But laser etching makes the surface melt and has little cutting effect.
Engraving has been the most cost-effective choice in some industries, while laser etching is a cost-effective choice with higher output, because it has better versatility.
Compared with engraving, laser etching mark does not have good wear resistance. Generally, etching marks last about 5 to 10 years, making them unsuitable for manufacturing heavy products or products exposed to harsh conditions. Laser engraving products are very durable due to deeper indentation, because its engraving marks are not easy to wear.
Under the same design, same material and output requirements, the cost of laser engraving is higher than that of laser etching, because it requires more time and more powerful machines and laser technology.
How to perform laser etching?
1. What materials are suitable for laser etching?
The type of material that the laser can etch depends on the laser used. Generally, CO2 lasers are used for etching nonmetals, and fiber lasers are used for metals. Diode laser is a low power laser, which is usually used by beginners and DIY enthusiasts to etch various types of soft materials, such as wood, plastic, fabric, etc. However, some special materials, such as anodized aluminum, laser usable brass, etc., can also be etched by CO2 and diode lasers, because they are composed of non-metallic layers on the base metal.
2. What type of laser can be used for laser etching?
Some sculptors may think that only fiber lasers can be used for laser etching. This is because etching is a process for metals, which react better to fiber lasers. In fact, the laser you need depends on the type of material you want to etch, not your marking process. Therefore, co2 laser engraving machine can also realize laser etching process on some materials.
The nature of the material determines the frequency required to properly penetrate the material and achieve permanent marking. In view of this, fiber laser and CO2 laser can easily produce this effect. Ideally, optical fiber lasers can only penetrate metals and other materials that require high frequencies. On the other hand, CO2 lasers will penetrate glass, wood and other low-frequency materials. Co2 laser engraving machine is a good tool for laser etching glass.
3. Process parameters of laser etching
The optimal process parameters of laser etching depend on the materials used for etching and the laser engraving machine. Some of the most important process parameters that affect the quality of laser etching are laser power, etching speed, spot size, etc. First of all, the power of the engraving machine used for etching cannot be too small or too large. It is better to use the engraving machine with medium power. The power is generally better to be above 30w. High power laser usually causes excessive burning of materials, which is not conducive to some minor etching. Secondly, the carving speed should be lower than the general carving speed. It is also easy to overlook that it is better not to use air assistance. Air assistance uses compressed air to protect the focus lens, promote the removal of engraving materials, and reduce the heat generated by the laser beam. However, using air assistance during laser etching will cause slight traces of materials on the surface and reduce the etching quality.