As a precision processing tool, wood engraving machines are widely used in engraving and cutting of various materials, such as wood products, plexiglass, glass, stone, crystal, Corian, paper, two-color plates, alumina, leather, resin, etc. However, there are some challenges and limitations when laser engraving machines are used to engrave metal. The following will analyze in detail the working principle, main applications, problems in metal engraving and their causes of laser engraving machines.
Ⅰ.Working rinciple of laser engraving machine
Wood engraving machines are mainly used for engraving and cutting in the following two ways:
1. Dot matrix engraving:
The principle of dot matrix engraving is similar to high-definition dot matrix printing. While the laser head swings left and right, it will engrave a line composed of a series of dots each time. As the laser head moves up and down, multiple lines eventually form a complete image or text. Whether it is scanned graphics, text, or vectorized graphics and text, dot matrix engraving can be used for processing. This method is suitable for engraving tasks that require high precision and detail.
2. Vector cutting:
Unlike dot matrix engraving, vector cutting is performed on the outer contour line of the graphics and text. This mode is often used for penetrating cuts on materials such as wood, acrylic, and paper, and can also be used for marking operations on the surfaces of a variety of materials. Vector cutting is suitable for work that requires precise cutting edges.
Ⅱ.Factors affecting engraving quality
When using a laser engraver, there are several key factors that affect the final engraving quality:
1. Engraving speed:
Engraving speed refers to the speed at which the laser head moves, usually expressed in inches per second (IPS). Higher speeds can improve production efficiency, but they also affect the depth and accuracy of engraving. Generally speaking, the slower the speed, the deeper the cutting or engraving. Users can adjust the speed from 1% to 100% through the engraving machine panel or the computer’s print driver, and the advanced motion control system ensures ultra-fine engraving quality even at high-speed engraving.
2. Engraving intensity:
Engraving intensity refers to the energy intensity of the laser beam hitting the surface of the material. For a specific engraving speed, the greater the intensity, the greater the depth of cutting or engraving. The intensity adjustment can also be achieved through the engraving machine panel or the computer’s print driver, with an adjustment range of 1% to 100%. Higher intensity means deeper cutting and engraving.
3. Spot size:
The size of the laser beam spot can be adjusted by using lenses with different focal lengths. Lenses with small spots are suitable for high-resolution engraving, while lenses with large spots are suitable for lower-resolution engraving and are the best choice for vector cutting. Typically, new equipment comes standard with a 2.0-inch lens, which has a moderate spot size and is suitable for a variety of occasions.
Ⅲ.Challenges of laser engraving metal
Although laser engravers perform well on non-metallic materials, they have significant problems with metal engraving. The main reasons are as follows:
1. Laser type:
Laser engravers usually use CO2 lasers, which work extremely well on non-metallic materials but are less efficient on metal materials. This is because metals have a low absorption rate for the wavelengths emitted by CO2 lasers, resulting in the energy not being fully transferred to the metal surface for effective engraving.
2. Laser power:
The laser tube power used by most laser engravers on the market currently belongs to the small and medium power range, and the maximum power is usually around 300W. For metal engraving, such power is not enough for deep or fine engraving. Metal materials require higher-power lasers for effective processing, which is beyond the capabilities of ordinary CO2 laser engravers.
Ⅳ.Solutions to metal engraving problems
In order to achieve high-quality engraving on metals, there are several methods to consider:
1. Use fiber lasers:
Fiber lasers are able to produce laser beams with higher energy density and their wavelengths are more suitable for absorption by metal materials. Therefore, fiber lasers can achieve better results in metal engraving.
2. Increase laser power:
Increasing the power of the laser engraver can enhance its ability in metal engraving. However, this requires upgrading and improving the equipment itself, which is costly.
3. Coating treatment:
Coating a layer of laser-absorbing material on the metal surface can improve the effect of CO2 lasers in metal engraving. Although this method cannot replace high-power lasers, it can improve the engraving quality to a certain extent.
Final Thoughts
In summary, laser engraving machines are widely used in non-metallic materials and have significant effects, but there are still certain technical limitations in metal engraving. By choosing the right type of laser, increasing the laser power, and taking some auxiliary methods, these problems can be solved to a certain extent and higher-quality metal engraving can be achieved.