Traditional cleaning industry has a variety of cleaning methods, mostly using chemical and mechanical methods. Nowadays, with the increasingly strict requirements of environmental protection laws and regulations and the increasing awareness of environmental protection and safety, the types of chemicals that can be used in industrial production cleaning will become less and less.
How to find a cleaner and non-destructive cleaning method is a problem we have to consider. Laser cleaning is considered to be the most reliable and effective solution because it has the characteristics of no grinding, no contact, no thermal effect and suitable for all kinds of materials. At the same time, laser cleaning can solve the problem that traditional cleaning methods can not solve.
Physical principle of laser cleaning
The beam emitted by the laser is absorbed by the pollutant layer on the surface to be treated. The absorption of large energy forms a rapidly expanding plasma (highly ionized unstable gas), which produces shock wave. The shock wave causes the pollutants to fragment and be removed.
Compared with traditional cleaning methods such as mechanical friction cleaning, chemical corrosion cleaning, liquid solid strong impact cleaning and high frequency ultrasonic cleaning, laser cleaning has five obvious advantages
Advantages of environmental protection: laser cleaning is a “green” cleaning method, without the use of any chemicals and cleaning solution, the waste is basically solid powder, small volume, easy to store, recyclable, no photo-chemical reaction, no pollution. It can easily solve the problem of environmental pollution caused by chemical cleaning. Often a fan can solve the problem of cleaning waste
Effect Advantage: the traditional cleaning method is often contact cleaning, which has mechanical force on the surface of the object to be cleaned, damages the surface of the object or the cleaning medium adheres to the surface of the object to be cleaned, and can not be removed, resulting in secondary pollution. The non grinding, non-contact and non thermal effect of laser cleaning will not damage the substrate, so these problems can be solved easily.
Control Advantages: the laser can be transmitted through optical fiber, cooperate with robot hand and robot, realize remote operation conveniently, and can clean the parts that are not easy to reach by traditional methods, which can ensure the safety of personnel in some dangerous places.
Convenient Advantages: laser cleaning can remove various types of pollutants on the surface of various materials, reaching the cleanliness that conventional cleaning cannot achieve. It can also selectively clean the pollutants on the surface of the material without damaging the surface of the material.
Cost Advantage: laser cleaning speed, high efficiency, save time; Although the one-time investment in the early purchase of laser cleaning system is high, the cleaning system can be used stably for a long time with low operation cost, and more importantly, it can realize automatic operation conveniently. Cost calculation: the cleaning efficiency of a single unit is 8 square meters, and the operation cost is about 5 kwh per hour, that is, the cleaning cost is 40 cents per square meter, excluding the initial cost, the later cost is 40 cents per square meter.
Application of laser cleaning in various fields
Laser cleaning technology is a new cleaning technology developed rapidly in recent 10 years. It has gradually replaced the traditional cleaning technology in many fields with its own advantages and irreplaceable. Laser cleaning not only can be used to clean organic pollutants, but also can be used to clean inorganic substances, including metal corrosion, metal particles, dust and so on. The following describes some practical applications, these technologies have been very mature, has been widely used.
1. Mold cleaning
Every year, hundreds of millions of tires are manufactured by tire manufacturers all over the world. In the production process, the cleaning of tire mold must be fast and reliable to save downtime. The traditional cleaning methods include sandblasting, ultrasonic or carbon dioxide cleaning, but these methods usually have to be moved to the cleaning equipment after the high heat mold is cooled for several hours. The cleaning time is long, and it is easy to damage the accuracy of the mold. Chemical solvent and noise will also cause safety and environmental protection problems.
Using laser cleaning method, the laser can be transmitted by optical fiber, so it has deep flexibility in use; Because the laser cleaning method can be connected with optical fiber to guide the light to the dead corner of the mold or the part that is not easy to clean, so it is convenient to use; Since the rubber is not gasified, it will not produce poisonous gas, which will affect the safety of the working environment.
The technology of laser cleaning tire mold has been widely used in the tire industry in Europe and the United States. Although the initial investment cost is high, it can save standby time, avoid mold damage, work safety and save raw materials.
According to the cleaning test carried out on the production line, it is shown that a set of large truck tire mold can be cleaned online in only 2 hours. Compared with the conventional cleaning method, the economic benefit is obvious.
2. Cleaning of weapons and equipment
Laser cleaning technology is widely used in weapon maintenance. With the laser cleaning system, the rust and pollutant can be removed efficiently and quickly, and the cleaning parts can be selected to realize the automation of cleaning. Using laser cleaning, not only the cleanliness is higher than chemical cleaning process, but also almost no damage to the surface of the object.
By setting different parameters, a dense oxide protective film or molten metal layer can be formed on the surface of metal objects, which can improve the surface strength and corrosion resistance. The waste removed by laser basically does not pollute the environment, and can be operated remotely, which effectively reduces the damage to the health of operators.
3. Cleaning of old aircraft paint
In Europe, laser cleaning system has been used in aviation industry for a long time. The surface of the aircraft needs to be repainted after a certain period of time, but the old paint needs to be completely removed before painting. The traditional mechanical paint removal method is easy to cause damage to the metal surface of aircraft, which brings hidden danger to safe flight. If multiple laser cleaning systems are used, the paint layer on the surface of an A320 Airbus can be completely removed within two days without damaging the metal surface.
4. Cleaning of external walls of buildings
With the rapid development of China’s economy, more and more skyscrapers have been built, and the cleaning problem of the building’s external wall is increasingly prominent. The laser cleaning system provides a good solution to the cleaning of the building’s external wall through optical fiber. It can effectively clean all kinds of pollutants on all kinds of stone, metal and glass, and is many times higher than the conventional cleaning efficiency. It can also remove the black spots and color spots on various stone materials of buildings.
5. Cleaning in electronic industry
The electronic industry uses laser to remove oxides: the electronic industry needs high-precision decontamination, especially suitable for the use of laser to remove oxides. Before PCB welding, the component pins must be thoroughly deoxidized to ensure the best electrical contact, and the pins must not be damaged in the process of decontamination. Laser cleaning can meet the use requirements, and the efficiency is very high, a pin only needs to irradiate a laser.
6. Precise cleaning of ester removal in precision instrument industry
In the precision machinery industry, it is often necessary to remove the esters and mineral oil used for lubrication and corrosion resistance on the parts, usually by chemical methods, but chemical cleaning often still has residues. Laser de esterification can completely remove esters and mineral oil without damaging the surface of parts. The pollutant removal is completed by shock wave, and the explosive gasification of oxide thin layer on the surface of parts forms shock wave, which leads to the pollutant removal, rather than mechanical interaction. The material is thoroughly deastered and used to clean the mechanical parts of aerospace industry. The removal of oil esters in the processing of mechanical parts can also be carried out by laser cleaning.
7. Pipe cleaning in reactor of nuclear power plant
The laser cleaning system is also used to clean the pipes in the reactor of nuclear power plant. It uses optical fiber to introduce high-power laser beam into the reactor to directly remove the radioactive dust, which is convenient to clean the material. And because it is remote operation, it can ensure the safety of the staff.