Before any laser cleaning, first determine what the contaminants are and what the base material is, then choose the appropriate laser type, select the appropriate laser cleaning equipment, and adjust the appropriate laser parameters to achieve the perfect cleaning effect.
There are currently three main types of lasers used in laser cleaning: fiber laser with a wavelength of 1064 nanometers, carbon dioxide laser with a wavelength of 10600 nanometers, and laser with a wavelength of 355 nanometers.
In the early days, carbon dioxide laser and fiber laser were mainly used. Excimer lasers can also remove paint, but they are too expensive.
Generally speaking, renovating construction vehicles is accompanied by rust removal and paint removal. These two contaminants are different substances and require different laser equipment to clean. The contaminant is the rust layer, and the base material is metal. Based on this feature, choose the most cost-effective continuous fiber laser cleaning machine.
Its working principle is:
Fiber laser has strong absorption rate for rust layer and pollutants. Relatively speaking, the absorption rate of rust layer is higher when the laser energy density is set at a suitable value. It can just remove the rust layer without damaging the metal base, thereby achieving the purpose of rust removal. This appropriate value lies between the cleaning threshold and the damage threshold. As the laser energy density increases, the laser energy density that can just clean the rust layer is called the cleaning threshold, and the value that can just damage the base metal is called the damage threshold. The laser energy density must be between the cleaning threshold and the damage threshold to achieve perfect rust removal.
Generally speaking, it is most appropriate to choose a value that is 80% of the damage threshold. Contaminants are seven layers, and the best option is the carbon dioxide laser. Because the paint has a high absorption rate of carbon dioxide laser and a low absorption rate of the base metal, there is a large room for error. The cleaning effect and cleaning efficiency are much higher than those of fiber lasers of the same power. It also has a cleaning threshold and a damage threshold. If the laser energy density is high enough, it will also damage the base metal. However, the range between its cleaning threshold and damage threshold is very large. You need to pay attention to the definition of the damage threshold.
for metal substrates. The metal will heat up rapidly after absorbing laser energy. When the temperature reaches the melting point of the metal, the metal will be damaged. Therefore, the laser energy density is adjusted to ensure that the metal temperature is lower than the melting point. For precision metal substrates, its melting point is 1500 degrees, but if the cleaning process temperature is higher than 900 degrees, it will easily react with oxygen in the air, and the metal will be oxidized and its stiffness will be reduced. If you want to remove rust from precision metal, you must use a pulsed fiber laser cleaning machine.
What is pulsed fiber laser?
Fiber laser is divided into continuous laser and pulse laser. A continuous laser is similar to a steady light, and a pulsed laser is similar to a flashing light. The continuous laser rust removal process is similar to high-pressure water gun rust removal. The pulse laser is equivalent to the rust removal after spraying. The dense single pulse energy hits the rust. While the rust absorbs the laser energy and vaporizes, it also has a vibration function. Therefore, the pulse laser Rust can be removed at lower temperatures.
In practical applications, many people can use fiber laser to remove paint, but its paint removal efficiency is very low. Moreover, it is easy to damage the base metal, so it is a bad idea to choose it. Why are carbon dioxide laser cleaning machines not popular? Because it is much bulkier and more expensive than fiber lasers.
Fiber laser can use flexible fiber optic lines to transmit laser light, but carbon dioxide laser cannot be transmitted using fiber optic lines and can only be transmitted using light guide arms, thus limiting its scope of use. Carbon dioxide laser is also a very cost-effective laser. As the price of laser equipment continues to decrease, its paint removal economy gradually surpasses traditional sandblasting and pickling processes.
Three years ago, the power of laser rust remover was about 1000W and 1500W, and the average rust removal was about 20 square meters per hour. Now the laser rust remover has reached the 6000W level, and the rust removal efficiency has reached about 100 square meters per hour. At present, carbon dioxide laser paint removal equipment is at the 300W and 600W levels, and it will not take long to upgrade to the 3000W level. The rust removal efficiency will be more than ten times that of today.