The laser cleaning system is a successful application of laser technology in the engineering field. Its basic principle is to utilize the high energy density of the laser to interact with the contaminants attached to the workpiece substrate, causing them to undergo instant heating, expansion, melting, and gasification, thereby separating them from the workpiece substrate. Laser cleaning technology is characterized by high efficiency, environmental friendliness, energy saving, and has been successfully applied in areas such as tire mold cleaning, aircraft paint removal, and cultural heritage restoration.
Traditional cleaning techniques include mechanical friction cleaning (such as sandblasting and high-pressure water jet cleaning), chemical corrosion cleaning, ultrasonic cleaning, dry ice cleaning, and so on. These cleaning techniques have been widely used in various industries. For example, sandblasting cleaning can remove metal rust, metal surface burrs, and three-proof paint on circuit board surfaces by selecting abrasives with different hardness. Chemical corrosion cleaning technology is widely used in the cleaning of equipment surface oil stains, boiler scale, oil pipeline, and other areas. Although these cleaning techniques have matured, they still have some issues. For instance, sandblasting cleaning can easily cause damage to the treated surface, while chemical corrosion cleaning can lead to environmental pollution and surface corrosion if not handled properly.
The emergence of laser cleaning systems represents a revolution in cleaning technology. Laser rust removal tools utilize the advantages of high energy density, high precision, and efficient conduction of lasers. They have significant advantages over traditional cleaning techniques in terms of cleaning efficiency, cleaning precision, and cleaning hard-to-reach areas. Laser cleaning effectively avoids the environmental pollution caused by chemical corrosion cleaning and does not damage the substrate.
Principle of Laser Cleaning System
So what is a laser cleaning system? Similar to other laser devices, a laser cleaning machine requires a control system to manage key parameters such as laser power, beam size, focal point, and more. It has a high degree of automation, and the current intelligent control systems can effectively identify and target edges and corners for cleaning, thereby improving cleaning speed and quality.
As an intelligent industrial application software, a laser cleaning system possesses powerful capabilities. To optimize the laser cleaning effect on the surface of the object being cleaned, various process parameters need to be considered, including laser cleaning methods, cleaning models, wavelength of the laser, energy density, power, pulse frequency, pulse duration, and the incident angle of the laser. Pulse lasers are capable of effectively removing rust from the surface of carbon steel. Only by studying and optimizing the process parameters can an efficient laser cleaning system be developed. For example, the pulse width: Laser cleaning can change the grain structure and orientation on the surface of the substrate without damaging it, and it can also control the surface roughness of the substrate, thereby enhancing the overall performance of the substrate.
Technological Applications of Laser Cleaning
（1）Semiconductor Industry
Laser cleaning finds applications in the semiconductor industry, specifically for cleaning semiconductor wafers and optical substrates. Both semiconductor wafers and optical substrates undergo similar processes during manufacturing, where raw materials are cut, ground, or processed into the desired shape. This process introduces particulate contaminants that are difficult to remove and can lead to repetitive contamination issues. Contaminants on the surface of semiconductor wafers can impact the quality of circuit board printing, thus shortening the lifespan of semiconductor chips. Contaminants on the surface of optical substrates can affect the quality of optical devices and coatings, potentially causing energy non-uniformity and reducing their lifespan. Due to the risk of surface damage to the substrates, dry laser cleaning methods are less commonly used in the cleaning of semiconductor wafers and optical substrates. Instead, laser wet cleaning and laser-induced plasma shockwave cleaning have been successfully applied in this field. Followed by cleaning using a laser rust removing tool. The cleaning effect was satisfactory, with a significant decrease in the size and coverage area of impurity particles, although the overall number of impurity particles per unit area increased. This method effectively removes micron-level particulate contaminants from the ultra-smooth surface of optical substrates.
（2）Metal Materials Industry
Compared to the cleaning of semiconductor wafers and optical substrates, the cleaning of metal surfaces deals with contaminants on a macroscopic scale. Contaminants on metal surfaces mainly include oxide layers (rust), paint coatings, coatings, and other adhered substances. These contaminants can be categorized into organic pollutants (such as paint coatings, coatings) and inorganic pollutants (such as rust layers). The primary purpose of cleaning metal surface contaminants is to meet subsequent processing or usage requirements. For example, prior to welding titanium alloy components, the oxide layer, which is approximately 10 μm thick, needs to be removed from the material surface. During aircraft maintenance, the existing paint coatings on the skin surface must be removed for re-coating purposes. Rubber tire molds require regular cleaning of attached rubber particles to ensure surface cleanliness and, consequently, the quality and lifespan of tire production molds. The damage threshold of metal materials is higher than the laser cleaning threshold for surface contaminants. By selecting suitable laser rust removal tools, excellent cleaning results can be achieved.
（3）Cultural Heritage Field
Metal artifacts and stone artifacts, among others, accumulate pollutants such as dirt and ink stains on their surfaces due to their long history. These contaminants need to be removed to restore the artifacts. Paper-based artifacts, such as calligraphy and paintings, can develop mold and fungal stains on their surfaces if stored improperly. These stains significantly affect the original appearance of the paper, especially for culturally or historically valuable documents, impacting their appreciation and preservation.
Laser cleaning systems can effectively eliminate fungal stains on Xuan paper, a type of traditional Chinese paper. Experimental results have shown that a single laser scan with an energy density of 3.2 J/mm² can remove thin fungal stains, while two scans are required for complete removal of the stains. However, it is important to note that using excessively high laser energy can potentially damage the Xuan paper while removing the stains.
Development Trends of Laser Technology
(1) Expansion of Applications in Existing Fields and New Application Areas. Laser cleaning technology has already found mature applications in fields such as paint stripping and rust removal. In recent years, there have been reports on utilizing laser cleaning to remove the oxide layer on metal wires. Expanding the application scope in existing fields and exploring new application areas provide fertile ground for the development of laser cleaning technology.
(2) Development of New Laser Cleaning Devices and Systems. The development of new laser cleaning devices will likely diverge into two categories. One category includes versatile devices that cover multiple application fields, such as a single device capable of both paint stripping and rust removal. The other category involves specialized devices tailored to specific needs, such as designing specific fixtures or using optical fibers to clean contaminants in confined spaces. Another popular application direction is the integration of laser cleaning with industrial robots to achieve fully automated laser cleaning processes.
Conclusion
Laser cleaning systems and laser rust removing tools are revolutionizing the field of rust removal. Their non-contact, precise, and environmentally friendly approach offers numerous advantages over traditional methods. From large-scale industrial operations to delicate restoration projects, laser cleaning technology is transforming the way we tackle rust, providing efficient, safe, and sustainable solutions. As further advancements are made and new applications explored, the potential for laser cleaning to revolutionize rust removal across various industries and everyday life continues to expand.
