Laser cleaning systems in the modern cleaning industry

 The traditional cleaning industry is mainly the use of chemicals or mechanical methods. With China's environmental protection regulations becoming increasingly strict, environmental safety awareness is growing, and chemical cleaning of industrial production the drawbacks, and will be replaced by laser cleaning. Laser cleaning has a non-abrasive, non-contact, non-thermal effect and applies to a variety of materials and other cleaning characteristics of the object, which is considered to be the most reliable and effective solution.

Laser Cleaning Principle

Laser cleaning technology refers to the process of irradiating the surface of a workpiece with a high-energy laser beam to cause instantaneous evaporation or stripping of dirt, rust spots, or coatings on the surface, thus achieving cleanliness. Laser and the light around us (visible and invisible light) are not different, except that the laser uses resonant cavities to gather the light in the same direction, and has a simpler wavelength, coordination, and other properties are better, so theoretically all wavelengths of light can be used to form a laser, but in practice is limited by the ability to excitation of the medium is not much, and therefore can produce a stable and suitable for industrial production of the laser light source is rather Limited. Nd: YAG lasers, carbon dioxide lasers, and excimer lasers are widely used.

 

The laser cleaning mechanism is mainly based on the object surface pollutants absorbing laser energy, or vaporization and volatilization, or instantaneous thermal expansion to overcome the surface of the particle adsorption force, so that it is detached from the surface of the object, and thus achieve the purpose of cleaning. Summarized roughly including laser vapor decomposition, laser stripping, dirt particle thermal expansion, substrate surface vibration, and particle vibration in four aspects; and the results of laser cleaning are often a variety of mechanisms at the same time

 

According to the analysis of a large number of experimental results, it is believed that the laser cleaning mechanism varies according to the difference in the thermophysical parameters of the surface adherent and the substrate. When the surface adhesion and the substrate material thermophysical parameter difference are large, the laser cleaning mechanism includes ablation vaporization, thermal vibration and thermal shock mechanism, and acoustic wave vibration crushing mechanism, such as laser cleaning paint layer and rubber layer. When the surface attachment and the substrate material thermophysical parameters of the difference are not large, the main ablation vaporization mechanism is in play, such as laser rust removal.

Selection of lasers

At present, there are more types of lasers, such as CO2 lasers, Nd: YAG lasers excimer lasers, etc., which can realize laser cleaning. But in general, in the higher precision requirements than the large volume removal or cost requirements, the excimer laser is the more appropriate tool, in other cases it is CO2 and solid-state lasers are better; For the microelectronics industry, the general choice of the excimer laser, such as KrF excimer, for the cleaning of molds and molds using CO2 or YAG lasers is better; and for the removal of the laser dressing layer, CO2 For laser coating removal, CO2 lasers are effective, especially TEA CO2 lasers are very promising in this field. In addition, if you know the composition of the surface contaminants in advance, you can choose the type of laser according to the wavelength of contaminant absorption.

1. Mold Cleaning

The laser cleaning method is deeply flexible in its use, with easy cleaning of dead corners or hard-to-remove parts of the mold. The technology of laser cleaning of tire molds has been adopted in a large number of tire industries in Europe and the United States, and the benefits gained in terms of saving standby time, avoiding damage to the molds, work safety, and saving raw materials have been quickly recovered. According to the laser cleaning equipment in the tire company production line cleaning test shows that only 2 hours can be online cleaning of a set of large sets of heavy-duty tire molds; and conventional cleaning methods, compared with the economic benefits are obvious. The use of laser cleaning without chemical reagents is also particularly suitable for applications in the food industry where the anti-adhesive elastomer layer on the mold needs to be replaced regularly to ensure hygiene.



2. Weapons and equipment cleaning

Laser cleaning system can efficiently and quickly remove rust, and contaminants, and can be selected for the removal of the site, to realize the automation of cleaning. Not only is the cleanliness higher than that of chemical cleaning processes but there is virtually no damage to the object's surface. By setting different parameters, a dense oxide protective film or molten metal layer can also be formed on the surface of metal objects to improve surface strength and corrosion resistance. The waste material removed by the laser is basically non-polluting to the environment and can be operated at a distance, effectively reducing the health damage to the operator.

3. Removal of old paint from airplanes

European laser cleaning systems have been widely used in the aviation industry. Before regular painting of aircraft surfaces, the old paint needs to be completely removed, and traditional mechanical paint removal methods are prone to damage the metal surfaces of the aircraft, posing a potential risk to safe flights. Using multiple laser cleaning systems, the paint layer on the surface of an A320 Airbus can be completely removed within two days without damaging the metal surface.



4. Building exterior wall cleaning

The laser cleaning system provides a solution to the cleaning of building facades, which can effectively clean various pollutants on various types of stone, metal, and glass, and is many times more efficient than conventional cleaning. It can also remove the black spots and color spots on various stones of buildings. Laser cleaning systems in Songshan Shaolin Temple on buildings, and monuments for cleaning tests show that the use of laser cleaning to protect the ancient buildings to restore the appearance of the effect is very good.

5. Cleaning in the electronics industry

The electronics industry uses lasers to remove oxides. Before soldering on circuit boards, component pins must be thoroughly de-oxidized to ensure optimal electrical contact, and the pins must not be damaged while being decontaminated. Laser cleaning meets the requirements for use and is so efficient that only one laser exposure is needed for one pin.

6. Precision de-esterification cleaning in the precision machinery industry

The precision machinery industry often requires the removal of esters and mineral oils used for lubrication and corrosion resistance on parts, and chemical cleaning leaves residues. Laser de-esterification can completely remove esters and mineral oils without damaging the surface of the parts. The material is thoroughly de-esterized for the aerospace industry to clean mechanical parts, and the removal of oil and ester in the processing of mechanical parts can also be cleaned by laser.

7. Pipe cleaning in nuclear power plant reactors

The laser cleaning system is also applied to cleaning pipes inside the reactors of nuclear power plants. It uses optical fibers to introduce high-power laser beams into the reactor interior to directly remove radioactive dust, and the cleaned-down material is easy to clean up. And since it is operated at a distance, it can ensure the safety of the staff.

 

Laser cleaning plays an important role in many fields, including automobile manufacturing, semiconductor wafer cleaning, precision parts processing and manufacturing, military equipment cleaning, building facade cleaning, cultural relics protection, circuit board cleaning, precision parts processing and manufacturing, liquid crystal display cleaning, chewing gum residue removal and other fields can play an important role.

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