On the Internet, there are many kinds of explanations of the principle of laser rust removal in the book, most of them are too difficult to understand, what thermal effect, light benefit, optical mechanical effect, plasma and other complex concepts, it is easy to confuse the reader, for ordinary users there is no need to delve into these concepts, only need to understand the basic logic, will use the machine on it, today we will use the simplest language to explain the principle of laser rust removal.
In rust removal, the material is divided into 2 parts, the contaminant and the substrate material. The contaminant is the rust layer, the base material is metal, and laser rust removal is the use of a laser to remove the pollutant rust layer without damaging the base metal. The characteristic of laser is that different wavelengths of lasers have different absorption rates for different substances, and only need to choose a laser with a very high absorption rate of the rust layer to achieve a perfect rust removal effect. For example, the fiber laser with a wavelength of 1064nm has a high absorption rate of conductor materials, the carbon dioxide laser with a wavelength of 10600nm has a very high absorption rate of insulator materials, the green laser with a wavelength of 532nm has a very high absorption rate of semiconductor materials, and the ultraviolet laser with a wavelength of 355nm can absorb almost everything, which is a cold light source. The characteristics of laser absorption rate are: lasers with high absorption rate of conductor materials tend to have extremely low absorption rate of insulator materials, and vice versa, lasers with high absorption rate of insulator materials tend to have low absorption rate of conductor materials. Lasers with a high absorption rate of semiconductor materials also have a certain absorption rate for conductors and insulators. In laser rust removal, the contaminant is the rust layer, it is neither a conductor nor an insulator, its properties are similar to semiconductors, theoretically speaking, the wavelength of 532nm green laser has the highest absorption rate of semiconductor materials, it is the best choice for rust removal, but it is too expensive, the laser derusting machine on the market generally uses fiber laser, it is the cheapest laser, the most cost-effective laser, the lowest cost of derusting the laser.
The principle of fiber laser rust removal is: the wavelength of fiber laser is 1064nm, it has a high absorption rate of rust layer and base metal, laser welding, laser cutting all use fiber laser, which means that if the operation is improper, the base metal will be damaged. But the good news is that the reflectivity of the metal to the laser is much greater than that of the rust layer, the total energy of the laser = absorption + reflection + diffraction, the absorption rate of the laser by the rust layer is as high as more than 80%, the absorption rate of the metal to the laser is less than 20%, most of it is wasted by reflection, only a small part of the energy is absorbed by the metal, the reflectivity of the rust layer is much lower, it can absorb most of the laser energy, and the vaporization temperature of the rust layer is much lower than that of the base metal, so there is an intermediate value, which can just remove the rust without damaging the base metal, This value is in a small space. This spatial value is expressed by the laser energy density, as the laser energy density continues to increase, the value that can just remove the pollutant rust layer is called the cleaning threshold, and the value that can just damage the base metal is called the damage threshold, and the laser energy density must be between the cleaning threshold and the damage threshold. If the laser energy is below the cleaning threshold, it cannot vaporize the rust, no matter how many times it is scanned, it will not remove the rust, and if the damage threshold is exceeded, it will damage the base metal while removing the rust.
Being able to absorb laser energy is the basis of laser rust removal, in addition to fiber laser, carbon dioxide laser, ultraviolet laser, green laser have a certain absorption rate of the rust layer, which means that these lasers can be used to remove rust, laser rust removal machine is not limited to fiber laser, it is only one of the laser rust removal equipment, in actual combat should choose different machines according to different application scenarios, no matter what kind of laser equipment, rust removal logic is the same, determine the pollutants and substrate materials, choose the right laser, Adjust the appropriate laser parameters and design the appropriate process flow to achieve the perfect rust removal effect.