Laser cleaning is a green non-destructive surface cleaning technology that utilizes the interaction between laser and material to remove attachments on the substrate surface. The quality and efficiency of laser cleaning are influenced by the interaction of multiple parameters. When other parameters are the same, the higher the peak power, the higher the peak power density, and the easier it is to reach the threshold power density for the attachment to be cleaned, achieving the required cleaning effect.
There are four types of targets in the laser cleaning process, namely: 1) the attachment laser causes the attachment to expand under heat, and when the expansion force is greater than the attraction between the attachment and the substrate, the attachment falls off; Alternatively, laser can directly evaporate, vaporize, decompose, ablate, or burn the attached material. 2) The gas laser inside the attachment layer causes the environmental gas inside the attachment layer to plasma, causing an impact on the attachment and causing it to peel off. 3) The substrate laser generates thermoelastic waves on the substrate, causing the attachment to break and fall off. 4) The pre coated liquid film laser acts on the pre coated liquid film, causing it to explode and boil, transferring energy to the surface attachment, causing it to shatter and detach.
Laser cleaning has been rapidly applied in many production fields, such as removing glue from patterns inside molds, removing dust and scale from ancient buildings and stone cultural relics, removing rust from ship sheet surfaces, removing paint from aircraft metal skins and composite material components, and removing paint from high-speed rail surfaces.
The concept of laser cleaning was proposed in the late 1960s, but it was not until the early 1990s that it was truly applied in industrial production. After decades of research and development, laser cleaning has become a reliable technology capable of cleaning a large number of different substrates and attachments. The types of substrates that can be cleaned include copper, iron, steel, titanium, aluminum, composite materials, silicon, glass, stone, and paper, while the types of attachments include coatings, rubber, sulfides, oxides, particles, mud, oil, paint, scale, rust, and mold, which basically meet the cleaning needs of the petrochemical industry. At present, the application of laser cleaning in industry covers fields such as microelectronics, architecture, molds, automobiles, high-speed rail, cultural relics, nuclear power, ships, aerospace, etc., while the petrochemical field urgently needs to be developed. In recent years, higher power lasers have been developed abroad, and the laser cleaning equipment system has become more complete. The research scope has been continuously expanded and the level has been continuously deepened. The main research directions are process optimization, quality monitoring and characterization, and exploring the latest applications. Although it started late in China, universities, enterprises, and research institutes have already done a lot of basic process, mechanism research, and equipment research and development work. Driven by environmental protection needs and policies, laser cleaning in China is developing towards cluster industrialization, and the localization of core components such as high-power lasers still has a long way to go. The work of domestic and foreign researchers in mechanism research, experimental verification, process optimization, and practical applications provides a theoretical basis and practical reference for the application of laser cleaning in the petrochemical field.
Foreign laser technology started early and gave birth to large enterprises specializing in providing laser cleaning equipment and services. In recent years, based on previous research on processes and mechanisms, foreign research on laser cleaning has focused on process optimization, quality monitoring and characterization, and exploring new applications. Mateo et al. from Spain used laser cleaning to remove paint layers containing pollutants and pigments from brass samples. The energy and laser emission required for each pulse are reduced while ensuring the cleaning effect. The samples before and after cleaning were tested using an optical microscope and Fourier transform infrared spectrometer, and the results showed that the surface appearance of the samples was complete. It determines the cleaning process by monitoring the plasma emission signal, thereby finely regulating the cleaning process parameters. However, the cost of this method is high, and there are efficiency issues in industrial applications. Striova et al. in Italy used laser and traditional chemical cleaning methods to remove naturally aged and artificially aged shellac paint from mural substrates, and evaluated the cleaning process using optical tools.
The research and equipment development on laser cleaning in China started relatively late, with a significant gap in overall level compared to foreign countries, especially high-power laser cleaning equipment and solutions. In recent years, some universities, enterprises, and research institutes have gradually carried out research on the application of laser cleaning in the industrial field and developed laser cleaning equipment, with an increasing number of practical application cases.
In recent years, research on laser cleaning in China has mainly focused on exploring processes and mechanisms. According to the research objects, research has mainly focused on laser paint removal, laser rust removal, and laser cleaning of cultural relics.
The process and mechanism exploration work of researchers has proven that laser cleaning technology is safe and effective for various substrates and attachments in various fields, and its efficiency and quality can be improved through process optimization; The research on quality monitoring and characterization has improved the process control of laser cleaning.
About HGSTAR: HGSTAR is is a sub-brand of HGTECH.HGTECH the pioneer and leader of laser industrial application in China, and the authoritative provider of global laser processing solutions. We have comprehensively arranged laser intelligent machine, measurement and automation production lines, and smart factory construction to provide overall solutions for intelligent manufacturing.