Ordinary mechanical engraving cannot engrave dots of varying thickness in an economical way, so it does not have a grayscale expression. Laser engraving is achieved by dotting, which has a natural advantage in grayscale expression. For this reason, grayscale expression is used as much as possible in engraving design. The advantage is that on the one hand, it reduces the coloring process and saves costs; on the other hand, it enriches the means of engraving and increases the level of graphics.
Ⅰ.Wood
1. Wood selection
Logs (unprocessed wood) are the most commonly used laser processing materials so far, and they are easy to engrave and cut. Light-colored woods such as birch, cherry or maple can be well vaporized by lasers, so they are more suitable for engraving. Each type of wood has its own characteristics. Some are denser, such as hardwood, and a higher laser power is required when engraving or cutting.
2. Wood cutting
The depth of wood cutting by wood engraving machines is generally not deep, within 5mm. This is because the power of the laser is small. If the cutting speed is slowed down, it will cause the wood to burn. In specific operations, you can try to use large-size lenses and use repeated cutting methods.
3. Coloring
After engraving, colored wood will generally feel like it has been burned. It matches the wood base color and has a primitive artistic beauty. The depth of its color mainly depends on the laser power and engraving speed. But some wood is usually softer, and you can’t change its color anyway (such as camphor wood).
Ⅱ.Density veneer
1. Ordinary density veneer
This type of density board is the kind of wooden pallet we often use for sign lining. The material is high-density board with a thin wood grain on the surface. Laser can be engraved on this material factory, but the engraved pattern is uneven and black, and generally needs to be colored. Usually you can learn the appropriate design and use 0. 5mm two-color board for inlay to get better results.
2. Laser-specific density veneer
Some density boards are specially designed for laser engraving. The engraved pattern is uniform in color and has a good effect without coloring.
3. Cleaning
After engraving, you can use a damp cloth to clean the surface of the density board.
4. Coloring
You can use acrylic paint or alkyd paint. When engraving, the color of the graphic can be set to 60% grayscale, so that the bottom surface of the engraving has some pitting to improve the adhesion of the color. 3. Acrylic (a kind of organic glass)
Ⅲ.Acrylic
1. The process of engraving acrylic
Acrylic is the most commonly used engraving material after wood. It is easy to cut and engrave, has a variety of shapes and sizes, and is relatively low in cost. There are two production processes for organic glass: casting and calendering. Laser engraving mainly uses organic glass produced by casting, because the frosting effect it produces after laser engraving is very white, which is in sharp contrast to the original transparent texture.
2. Back engraving
In general, organic glass is engraved by back engraving, which makes the finished product more three-dimensional. When engraving, please mirror the graphic first, and the engraving speed should be fast and the power should be low. If the power is too high during engraving, uneven stripes will appear on the bottom surface. In the case of back engraving, the colored part should be engraved deeper first, and then polished with a flame polisher before filling in the color. If it is not polished, the color seen from the front will not be uniform.
3. Cleaning
Acrylic paint can be used for cleaning, and other paints may damage the finish of organic glass.
Ⅳ.Two-color board
1. Specifications of two-color board
Two-color board is a kind of engineering plastic specially used for engraving. It composed of two or more layers of colors. Its specifications are generally 600, 1200mm, and there are also a small number of brands with specifications of 600, 900mm. Two-color boards can be divided into two categories: mechanical and laser. Some mechanical boards can also be used for laser engraving.
2. Engraving two-color board
If you use a laser board, the engraving effect will be very good, with obvious contrast and clear edges. When using a mechanical board with a thinner surface, the engraving effect is not much different from that of a laser board. If you look closely, the edges may not be as clear as those of a laser board. On two-color boards with large contrast (such as black and white boards), grayscale images can designed for engraving. After a large amount of engraving, the two-color board itself may deformed. It can be heated with hot water and then flattened by hand.
3. Cutting two-color board
Generally, users will ask you to cut the two-color board. At this time, if you are using a laser board, you can cut it off after engraving. Be careful not to cut too slowly, and do not cut through at one time. Do it in three or four times, so that the edge of the cut material is smooth and there is no melting mark. The power should be just right during engraving, not too large, to avoid melting marks. If you use a mechanical board, you can only cut it to 50% depth, then break it by hand and smooth the edge with sandpaper. If the user has a mechanical machine, you can cut it on the mechanical machine first, and then move it to the wood engraving machine for engraving.
4. Cleaning
After engraving, you can use a damp cloth or alcohol to clean the surface. However, it should noted that if the laser power set too high during engraving. A layer of smoke that is difficult to wipe off may be attached to the surface of the two-color board.
5. Coloring
If the user’s requirements are not high, you can use dots to express the different colors in the logo. If you must paint, you must carve the painted area deeper. You can use acrylic paint or alkyd enamel paint. Other paints may damage the surface finish of the two-color board.
Ⅴ.Glass
1. Engraving glass
Glass engraving is usually difficult to control. Follow the steps below to create a smoother frosted surface. Apply a little detergent to the area to engraved, cut a piece of newspaper or napkin slightly larger than the area to engraved. Soak the paper completely with water, squeeze out the excess water, and place the wet paper on the area to engraved and flatten it without wrinkles. Place the glass in the engraving machine and engrave it while the paper is still wet, then remove the glass, remove the remaining paper, and clean the glass surface.
2. Combining laser engraving with sandblasting
Laser engraving machines can replace engraving machines and cut sandblasted protective films directly on glass. This process eliminates the transfer process of the protective film, saves time, and improves the quality of the finished product.
3. Cleaning
After engraving, you can use a damp cloth to clean the surface.
4. Coloring
You can use acrylic paint to color it.
5. Precautions
When engraving leaded crystals with lasers, you should be extra careful. Leaded crystals have different expansion coefficients from ordinary crystals, which can cause cracks or breakage of the crystals during engraving. Setting the power lower can avoid this problem, but you should still be on guard against cracks.
Ⅵ.Painted copper plate
1. Avoid oxidation
Painted copper plateUnder normal circumstances, copper cannot laser engraved. But now there is a material with a special paint film attached to its surface. And the laser can completely vaporize the paint film on the surface, and then expose the underlying copper plate. Usually manufacturers will polish or do special treatment on the copper plate before painting, so that the exposed area after engraving can have sufficient smoothness and can preserved for a long time. If the copper surface not treated, a protective film needs to applied again after engraving to avoid oxidation over time and surface contamination.
2. Engraving
Generally, low power and high speed can be used, and the accuracy can be set above 500dpi.
3. Cleaning
After engraving, you can use a damp cloth or alcohol to clean the surface.
4. Coloring
If the user’s requirements are not high, you can use dots to express the different colors in the logo. If you must paint, you can use acrylic paint. Other paints may damage the smoothness of the copper surface.
Final Thoughts
Laser engraving is a versatile and precise method for enhancing various materials, from wood and acrylic to glass and metal. By understanding the unique properties and optimal techniques for each material, one can achieve stunning and durable results. Whether for artistic expression or practical applications, laser engraving offers endless possibilities for creativity and innovation.
