Cleaning technology of the hottest laser equipment

2022-08-24
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Cleaning process of laser equipment

1 Preface

with the rapid development of science and technology, laser technology has been more and more applied to all fields of people's production and life. From bar codes and laser printers in supermarkets to laser cosmetology and myopia treatment, people are familiar with them. Many people also know that laser equipment is used for cutting, drilling and welding in industrial production. However, people are not familiar with and understand the application of laser equipment in the cleaning industry. 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. Why can the laser equipment be cleaned? What can be used for cleaning? How effective is the cleaning? Make a brief introduction

2. Laser and cleaning

there are various cleaning methods in the traditional cleaning industry, mostly using chemical agents and mechanical methods. 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 has the characteristics of no grinding, non-contact, no thermal effect and suitable for all kinds of materials, which is considered to be the most reliable and effective solution. At the same time, laser cleaning can solve the problems that cannot be solved by traditional cleaning methods. For example, when there are submicron pollution particles on the surface of the workpiece, these particles tend to stick very tightly, which cannot be removed by conventional cleaning methods, while cleaning the surface of the workpiece with nano laser radiation is very effective. Also because the laser is non-contact cleaning of the workpiece, it is very safe to clean the precision workpiece or its fine parts, which can ensure its accuracy. Therefore, laser cleaning has unique advantages in the cleaning industry

why can lasers be used for cleaning? Why won't it cause damage to the cleaned object? First, understand the essence of laser. In short, laser is no different from the accompanying light (visible light and invisible light) around us, but laser uses a resonator to concentrate light in the same direction, and has a simpler wavelength and better coordination. Therefore, theoretically, all wavelengths of light can be used to form a laser, but in fact, there are not many media that can be excited, Therefore, the laser light source that can produce stable and suitable for industrial production is quite limited. The widely used ones are probably nd:yag laser, 5 The prepared plywood samples are installed on the upper and lower clamps of the experimental machine, specifically carbon dioxide laser and excimer laser. Because nd:yag laser can be transmitted through optical fiber, which is more suitable for industrial applications, it is also widely used in laser cleaning

3. Advantages of laser surface cleaning

compared with traditional cleaning methods such as mechanical friction cleaning, chemical corrosion cleaning, strong impact cleaning of liquid and solid, high-frequency ultrasonic cleaning, laser cleaning has obvious advantages

3.1 laser cleaning is a "green" cleaning method, which does not require the use of any chemical agents and cleaning fluids. The waste after cleaning is basically solid powder, small in size, easy to store, recyclable, and can easily solve the environmental pollution caused by chemical cleaning

3.2 the traditional cleaning method is often contact cleaning, which has mechanical force on the surface of the cleaned object, damages the surface of the object or the cleaning medium is attached to the surface of the cleaned object, which cannot be removed, resulting in secondary pollution. The non abrasive and non-contact nature of laser cleaning solves these problems

3.3 laser can be transmitted through optical fiber, cooperate with robot hands and robots, conveniently realize long-distance operation, and can clean parts that are difficult to reach by traditional methods, which can ensure the safety of personnel in some dangerous places

3.4 laser cleaning can remove various types of pollutants on the surface of various materials, reaching a cleanliness that conventional cleaning cannot achieve. It can also selectively clean the pollutants on the material surface without damaging the material surface

3.5 laser cleaning has high efficiency and saves time

3.6 although the one-time investment in purchasing the laser cleaning system is high in the early stage, the cleaning system can be used stably for a long time with low operation cost. Taking laserlaste of Quantel company as an example, the operating cost per hour is only about 1 euro, and more importantly, it can easily realize automatic operation

4. The principle of laser surface cleaning

the process of pulsed nd:yag laser cleaning depends on the characteristics of the optical pulse generated by the laser, and is based on the photophysical reaction caused by the interaction between high-intensity beam, short pulse laser and pollution layer. Its physical principle can be summarized as follows:

A) the beam emitted by the laser is absorbed by the polluted layer on the surface to be treated

b) the absorption of large energy forms a rapidly expanding plasma (highly ionized unstable gas), producing shock waves

c) the shock wave turns the pollutants into fragments and is removed

d) the light pulse width must be short enough to avoid the accumulation of heat that destroys the treated surface

e) experiments show that when there is oxide on the metal surface, plasma occurs on the metal surface

plasma is produced only when the energy density is higher than the threshold, which depends on the polluted layer or oxide layer removed. This threshold effect is very important for effective cleaning under the condition of ensuring the safety of the substrate material. There is a second threshold for the occurrence of plasma. If the energy density exceeds this threshold, the substrate material will be destroyed. In order to effectively clean the substrate material on the premise of ensuring the safety of the substrate material, the laser parameters must be adjusted according to the situation, so that the energy density of the optical pulse is strictly between two thresholds

each laser pulse removes a certain thickness of pollution layer. If the pollution layer is relatively thick, multiple pulses are required for cleaning. The number of pulses required to clean the surface depends on the degree of surface contamination. An important result of the two thresholds is the self-control of cleaning. The light pulse whose energy density is higher than the first threshold will remove the pollutants until it reaches the base material. However, because its energy density is lower than the failure threshold of the substrate material, the substrate will not be damaged

5. Practical application of laser cleaning

laser cleaning can be used not only to clean organic pollutants, but also to clean inorganic substances, including metal rust, metal particles, dust, etc. Here are some practical applications. These technologies are very mature and have been widely used

5.1 mold cleaning:

every year, hundreds of millions of tires are manufactured by tire manufacturers all over the world. The cleaning of tire molds in the production process must be rapid and reliable to save downtime. Traditional cleaning methods include sand blasting, ultrasonic or carbon dioxide cleaning, but these methods usually have to be moved to the cleaning equipment for cleaning after the high heat mold is cooled for several hours. The cleaning takes a long time and is easy to damage the accuracy of the mold. Chemical solvents and noise will also produce safety and environmental protection problems. Using the laser cleaning method, because the laser can be transmitted by optical fiber, it is very flexible 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 remove for cleaning, it is convenient to use; Since the rubber is not gasified, it will not produce toxic gases, 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, the benefits obtained in saving standby time, avoiding mold damage, working safety and saving raw materials can be quickly recovered. According to the cleaning test carried out by the laserlaste Laser Cleaning Department of Quantel company on the production line of Shanghai shuangqian truck tire company, it only takes 2 hours to clean the mold of a set of large truck tires. Compared with conventional cleaning methods, the economic benefits are obvious

the anti sticking elastic film on the mold of the food industry needs to be replaced regularly to ensure hygiene. Laser cleaning without chemical reagents is also particularly suitable for this application

5.2 cleaning of weapons and equipment:

laser cleaning technology is widely used in weapon maintenance. With the laser cleaning system, rust and pollutants can be removed efficiently and quickly without rust, and the removal parts can be selected to realize the automation of cleaning. Using laser cleaning, not only clean 1 Add shims in the fixture; The degree is higher than that of chemical cleaning process, and there is almost no damage to the surface of the object. By setting different parameters, laserlaste of Quantel company can also form a dense oxide protective film or metal melting layer on the surface of metal objects to improve surface strength and corrosion resistance. The waste materials removed by laser basically do not pollute the environment, and can also be operated remotely, effectively reducing the health damage to operators

5.3 removal of old aircraft paint:

in Europe, laser cleaning systems have long been used in the aviation industry. The surface of the aircraft needs to be repainted after a certain period of time, but the original old paint needs to be completely removed before painting. The traditional mechanical paint removal method is easy to damage the metal surface of the aircraft and bring hidden dangers to the 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

5.4 cleaning of building exterior walls:

with the rapid development of China's economy, more and more skyscrapers have been established, and the cleaning problem of building exterior walls has become increasingly prominent. Laserlaste laser cleaning system provides a good solution to the cleaning of building exterior walls through optical fibers up to 70 meters long. It can effectively clean all kinds of pollutants on all kinds of stones, metals and glasses, and its efficiency is many times higher than that of conventional cleaning. It can also remove black spots and color spots on various stones of buildings. The cleaning test of laserlaste laser cleaning system on buildings and stone tablets in Shaolin Temple in Songshan shows that laser cleaning has a very good effect on protecting ancient buildings and restoring their appearance

5.5 cleaning in the electronic industry

the electronic industry uses laser to remove oxides: the electronic industry needs high-precision decontamination, which is particularly suitable for laser to remove oxides. Before welding the circuit board, the pins of components must be completely de oxidized to ensure the best electrical contact, and the pins must not be damaged during the decontamination process. Laser cleaning can meet the use requirements, and the efficiency is very high. One pin only needs to irradiate the laser once

5.6 precise degreasing cleaning in the precision machinery industry:

the precision machinery industry often needs to remove the esters and mineral oils used for lubrication and corrosion resistance on parts, usually by chemical methods, and chemical cleaning often still has residues. Laser deasterification 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 thin oxide layer on the surface of parts forms shock wave, which leads to the removal of pollutants, rather than mechanical interaction. The material is thoroughly deasterylated for the cleaning of mechanical parts in aerospace industry. Oil ester removal in machining of mechanical parts can also be used

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