Although the application of lasers in cutting, drilling, and welding is well-known, its use in industrial cleaning is relatively new and has vast unexplored space.
The need for a non-toxic, non-abrasive cleaning method in the market led to the emergence of laser cleaning as an alternative to chemical cleaning, manual cleaning, and abrasive blasting cleaning methods.
Advantages of Laser Cleaning
The main issues with traditional cleaning methods include negative environmental impacts and substrate wear, which can damage the fine surface of the substrate. The use of chemical solvents in cleaning also produces potentially hazardous vapor and liquid waste.
These limitations of traditional cleaning methods have led to the application of laser cleaning technology in surface cleaning fields.
Laser cleaning has numerous advantages and has become the most effective method for removing unwanted material from the surface of materials.
Currently, pulsed laser cleaning and coating removal systems are widely used in various fields, from removing sulfur residues from tire molds and engraving surfaces through ablation to stripping insulation layers from wires and removing coatings from fine surfaces.
The main advantages of using lasers in surface cleaning applications include:
- A non-destructive cleaning method
- Reduced waste generation
- Improved safety
- No need for chemical agents or sandblasting
- Non-abrasive and non-contact cleaning process
Applications of Laser Cleaning
(1) Surface finishing and rust removal in steel manufacturing
Laser cleaning is also an effective and efficient method for removing rust and oxide layers from metal surfaces. Rust and oxide layers are contaminants formed on the metal surface due to natural or artificial processes. When metals are exposed to moisture, they react with water to form ferrous oxide, which causes rusting. This type of rust reduces the quality of the metal, making it unsuitable for various applications.
On the other hand, due to the heat treatment process, an oxide layer forms on the metal surface. The oxide layer causes discoloration of the metal surface, hindering subsequent precision machining operations. To remove these unwanted surface deposits, a cleaning process is necessary to provide a smooth surface for pre-precision machining and precision machining (such as electroplating).
Traditional methods of rust and scale removal include physical methods such as sandblasting, polishing, scraping devices, extra-blowing, and wire brushing, as well as chemical methods such as using alkaline or acidic chemicals to remove the oxide layer.
However, these methods not only cause environmental pollution but also damage the substrate metal.
Therefore, laser cleaning is an excellent solution for removing unwanted surface deposits without causing damage to the metal substrate while producing minimal waste in an environmentally-friendly way.
To avoid these shortcomings, laser cleaning has become the preferred method for rust and scale removal. Laser beams with high peak power and high repetition frequencies are used to remove rust layers/oxide layers by irradiating them. The laser must emit short pulses to avoid causing damage to the metal. Rust rapidly absorbs the energy of the laser beam, causing temperature rise. Once the temperature is high enough, the rust melts and eventually evaporates.
Pulsed fiber laser is the primary choice because it provides greater control over power, wavelength, and pulse duration, allowing for the evaporation of rust/oxide layers without causing any imitation to the substrate material.
Laser cleaning technology can also be used for surface cleaning. Before applying a protective coating against corrosion to steel parts, the surface of the components must undergo a cleaning process to ensure that there is no contamination on its surface.
Surface cleaning/preparation requires the removal of all contaminants on the surface of steel parts to prepare for the application of a protective coating. These contaminants include oil, grease, oxide layers, hydrates, shop primers, etc.
Pulsed fiber laser cleaning uses non-abrasive and non-contact methods that do not involve solvents, chemicals, or grinding media.
Therefore, it is very suitable for surface cleaning preparation and rust/scale removal. The cleaning process can be performed on a small or large scale, and it can be automated.
Laser cleaning is an environmentally-friendly and cost-effective rust removal method that prepares the surface of the part for the application of a protective coating.
(2) Cleaning Anodic Components
In the aluminum smelting industry, carbon blocks are used as “sacrificial” anodes in primary aluminum production. The quality of the anodes affects the environmental, economic, and technical aspects of aluminum production. A small percentage of cell power is used to overcome the anode’s resistance.
The presence of dirt and pollutants increases the anode’s electrical resistance, leading to more cell power consumption. The presence of pollutants also shortens the life span of the anode by increasing the slag consumption rate during the melting process.
From an efficiency perspective, it is necessary to clean and remove all contaminants from the surface of anode components before using them for aluminum smelting operations.
In addition, anode components are valuable tools that can be reused but require thorough and careful treatment of their main components under specific conditions.
Laser cleaning can satisfy the specific conditions of reusable anode components. Laser cleaning can be used to:
- Remove residue
- Clean cathode rods
- Remove pollutants on bushings and short rods.
(3) Preparing for Metal Bonding
To improve process stability, surface adhesion, and better welding quality, the surface of the metal material to be connected must be prepared before applying welding and other connection techniques.
If the surface of the metal material is not properly cleaned before bonding, the joint and weld can easily degrade, leading to increased wear and even catastrophic failure. Laser cleaning can be used to prepare the surface before bonding, resulting in excellent bonding strength, improved corrosion resistance, and durability.
Laser cleaning is particularly suitable for applications involving curved surfaces or parts with highly complex three-dimensional geometries.
One of the main benefits of laser cleaning is its ability to fine-tune its power and wavelength for precise correction of metals used for microstructures, such as magnesium and aluminum. It also imparts high corrosion resistance to materials, ensuring stable and long-lasting bonding.
In recent years, adhesive bonding has become increasingly popular in structural design applications instead of traditional connection techniques such as riveting and welding.
This is because adhesive bonding offers many advantages over traditional techniques, including uniform stress distribution, reduced corrosion, weight reduction, vibration damping, and sound insulation. However, these benefits can only be achieved with careful surface cleaning preparation.
Laser cleaning is an ideal choice for such applications because it can carefully remove oil, rust, protective coatings, and other pollutants generated during transportation without damaging the substrate material.
(4) Preparing for Brazing and Welding
Laser cleaning has also been proven effective in pre-treatment applications for brazing and welding. In shipbuilding, precision tool manufacturing, automotive, and other related industries, the surfaces of aluminum and steel must undergo treatment before welding.