Introduction to the classification of Laser-Cleaning technology
Laser-Cleaning technology makes use of the characteristics of the above-mentioned laser to achieve the purpose of cleaning. According to the optical characteristics of the substrate material to be cleaned and the dirt to be cleaned, the Laser-Cleaning mechanism can be divided into two categories:
One is to use cleaning substrates and surface attachments to have a great difference in the absorption coefficient of a certain wavelength of laser energy. Most of the laser energy radiated to the surface is absorbed by the surface attachments, so that it is heated or vaporized and evaporated, or instantly expanded, and is driven by the formed airflow to separate from the surface of the object to achieve the purpose of cleaning. The substrate will not be damaged due to the very small absorption energy of the laser of this wavelength. For this kind of laser cleaning, choosing the right wavelength and controlling the laser energy is the key to achieving safe and efficient cleaning.
Another type of cleaning method is suitable for cleaning the laser energy absorption coefficient of the substrate and the surface attachments, or the substrate is more sensitive to the acid vapor formed by the heating of the coating, or the coating will generate toxic substances after the heating. This type of method usually uses high-power and high-repetition rate pulsed lasers to impact the cleaned surface to convert part of the beam into sound waves. After the sound wave hits the hard surface of the lower layer, the returned part interferes with the incident sound wave generated by the laser, generating high-energy waves, causing the coating to explode in a small area. The coating is compressed into powder and then removed by the vacuum pump. It won't hurt.
Introduction to the use of Laser-Cleaning
Laser-Cleaning is a very common cleaning technology, but many people don't understand the purpose of Laser-Cleaning.
1. Mold cleaning
The Laser-Cleaning method is flexible in use, and the dead corners or parts of the mold that are not easy to clean are easy to clean. The technology of Laser-Cleaning tire molds has been widely adopted in the tire industry in Europe and the United States, and the benefits obtained in saving standby time, avoiding mold damage, working safety, and saving raw materials are quickly recovered.
2. Weapon cleaning
The Laser-Cleaning system can remove rust and pollutants efficiently and quickly, and can select the removal part to realize the automation of cleaning. Not only the cleanliness is higher than the chemical cleaning process, but also almost no damage to the surface of the object.
3. Removal of old aircraft paint
European Laser-Cleaning systems have been widely used in the aviation industry. The original old paint needs to be completely removed before regular painting on the surface of the aircraft. The traditional mechanical paint removal method can easily cause damage to the metal surface of the aircraft and bring hidden dangers to safe flight.
4. Building exterior wall cleaning
The Laser-Cleaning system provides a solution to the cleaning of the exterior walls of buildings. It can effectively clean various contaminants on various stones, metals, and glass, and the efficiency is many times higher than that of conventional cleaning. It can also remove black spots and stains on various stones of buildings. The cleaning test of the Laser-Cleaning system on the buildings and stone steles in Songshan Shaolin Temple shows that the use of Laser-Cleaning has a very good effect on protecting the appearance of ancient buildings and restoring the appearance.
Introduction to the characteristics of Laser-Cleaning
According to the analysis of a large number of experimental results, the laser-cleaning mechanism is different according to the difference between the surface attachment and the thermal physical parameters of the matrix. When the thermal physical parameters of the surface attachment and the matrix material are quite different, the laser-cleaning mechanism includes: ablation vaporization, thermal vibration and thermal shock mechanism, and acoustic vibration mechanism, such as laser-cleaning paint and rubber layers. Compared with the traditional cleaning process, laser-cleaning technology has the following characteristics:
1. It is a kind of "dry" cleaning, no cleaning fluid or other chemical solutions are needed, and the cleanliness is much higher than that of chemical cleaning processes;
2. The scope of dirt removal and the scope of applicable substrates are very wide;
3. By adjusting the laser process parameters, it is possible to effectively remove contaminants without damaging the surface of the substrate, so that the surface is as old as new;
4. Laser-cleaning can easily realize automatic operation;
5. The laser decontamination equipment can be used for a long time, and the operating cost is low;
6. Laser-cleaning technology is a "green" cleaning process. The eliminated waste is solid powder, small in size, easy to store, and basically does not pollute the environment.
About laser-cleaning technology introduction
Laser-Cleaning technology refers to the use of high-energy laser beams to irradiate the surface of the workpiece to make the dirt, rust or coating on the surface evaporate or peel instantly, so as to achieve a clean process.
The laser is no different from the light around us, except that the laser uses a resonant cavity to gather light in the same direction, and has a simpler wavelength, better coordination and other performance, so in theory all wavelengths of light can be used To form a laser, it is actually limited by the fact that there are not many media that can be excited, so the laser light source that can produce stable and suitable for industrial production is quite limited.
The mechanism of Laser-Cleaning is mainly based on the fact that contaminants on the surface of the object absorb the laser energy, either vaporize or evaporate, or instantly expand by heat to overcome the adsorption force of the particles on the surface and make them detach from the surface of the object, thereby achieving the purpose of cleaning. To sum up, it roughly includes four aspects: laser vaporization and decomposition, laser peeling, thermal expansion of dirt particles, substrate surface vibration and particle vibration; and laser cleaning is often the result of multiple mechanisms acting simultaneously.
About the characteristics and introduction of laser-cleaning
The light beam emitted by the laser is absorbed by the contaminant layer on the surface to be treated. The absorption of large energy forms a rapidly expanding plasma, generating shock waves. The shock wave turns the contaminants into fragments and is removed. Compared with traditional cleaning methods such as mechanical friction cleaning, chemical corrosion cleaning, liquid and solid strong impact cleaning, and high-frequency ultrasonic cleaning, laser-cleaning has five obvious advantages:
Environmental protection advantages: laser-cleaning is a "green" cleaning method. It does not need to use any chemicals and cleaning fluids. The cleaned waste is basically solid powder, small in size, easy to store, recyclable, no photochemical reaction, no Will produce pollution. It can easily solve the environmental pollution problem caused by chemical cleaning. Often a single exhaust fan can solve the problem of waste generated by cleaning.
Effect advantage: The traditional cleaning method is often contact cleaning, which has mechanical force on the surface of the cleaning object, damages the surface of the object or the cleaning medium adheres to the surface of the object to be cleaned, and cannot be removed, resulting in secondary pollution. Grinding and non-contact, no thermal effect will not damage the substrate, so that these problems can be easily solved.
Control advantages: The laser can be transmitted through optical fibers, cooperate with robots and robots to easily realize remote operation, and can clean parts that are not easily reached by traditional methods. This can ensure the safety of personnel when used in some dangerous places.
Convenient advantage: Laser cleaning can remove various types of contaminants on the surface of various materials to achieve a cleanliness that cannot be achieved by conventional cleaning. It can also selectively clean the contaminants on the surface of the material without damaging the surface of the material.
Cost advantages: laser-cleaning is fast, efficient, and time-saving; although the initial one-time investment is relatively high when purchasing a laser-cleaning system, the cleaning system can be used stably for a long time, with low operating costs, and more importantly, it can be easily automated.
Principles and characteristics of Laser-Cleaning
The laser-cleaning is characterized by high directivity, monochromaticity, high coherence and high brightness. Through the focus of the lens and the Q switch, the energy can be concentrated into a small space and time range. In the laser-cleaning process, the following characteristics of the laser are mainly used:
1. The laser can achieve a high concentration of energy in time and space. The focused laser beam can generate thousands of degrees or even tens of thousands of degrees in the vicinity of the focal point, which can instantly evaporate, vaporize or decompose dirt.
2. The divergence angle of the laser beam is small and the directivity is good. The laser beam can be condensed into spots of different diameters through the condensing system. Under the condition of the same laser energy, controlling the laser beam spot with different diameters can adjust the energy density of the laser, so that the dirt will be heated and expanded. When the expansion force of the dirt is greater than the adsorption force of the dirt to the substrate, the dirt will be separated from the surface of the object.
3. The laser beam can generate ultrasonic waves on the solid surface to generate mechanical resonance and break the dirt off. Laser cleaning technology makes use of the characteristics of the above-mentioned laser to achieve the purpose of cleaning. According to the optical characteristics of the substrate material to be cleaned and the dirt to be cleaned, the laser cleaning mechanism can be divided into two categories:
One is to use the cleaning substrate (also called the matrix) and the surface attachment (dirt) to have a great difference in the absorption coefficient of a certain wavelength of laser energy. Most of the laser energy radiated to the surface is absorbed by the surface attachments, so that it is heated or vaporized and evaporated, or instantly expanded, and is driven by the formed airflow to separate from the surface of the object to achieve the purpose of cleaning.
Another type of cleaning method is suitable for cleaning the laser energy absorption coefficient of the substrate and the surface attachments, or the substrate is more sensitive to the acid vapor formed by the heating of the coating, or the coating will generate toxic substances after the heating.