Comparative advantages of laser cleaning over other conventional cleanings

Comparative advantages of laser cleaning over other conventional cleanings

To begin with, I would like to introduce the principles of laser cleaning briefly.

Laser cleaning for rust and paint removal is based on the following principles.

1. Ablation Principle

When the high - energy laser beam irradiates the surface of the object with rust or paint, the energy of the laser is absorbed by the contaminants such as rust and paint layers. The absorbed laser energy causes a rapid increase in temperature. At a high enough temperature, the materials of rust and paint vaporize or sublimate. For example, the temperature of the laser - irradiated area can reach thousands of degrees Celsius in an instant. The rust (mainly iron oxides) and paint coatings have different boiling points and sublimation points. As the temperature rises above these critical values, they are removed from the substrate surface in the form of gas.

2. Shock Wave Principle

The high - energy laser pulse generates a shock wave when it acts on the surface. When the laser energy is concentrated on a small area in a very short time, a plasma is formed on the surface of the material due to the extremely high temperature and pressure. The rapid expansion of this plasma generates a shock wave that propagates through the rust and paint layers. This shock wave exerts a mechanical force on the contaminants, causing them to break away from the substrate. The shock wave can penetrate through the micro - cracks and interfaces of the rust and paint, weakening the adhesion between the contaminants and the substrate and facilitating their removal.

The high-energy-density laser beam is used to irradiate the surface of the workpiece, causing the dirt, rust or coating on the surface to evaporate or peel off instantly, thus achieving cleaning and purification.

3. Photothermal and Photochemical Effects

In addition to the above - mentioned ablation and shock wave effects, the laser also has photothermal and photochemical effects. The photothermal effect is mainly manifested as the heat generated by the absorption of laser light, which causes the temperature of the material to rise, leading to the decomposition and removal of rust and paint. The photochemical effect is due to the fact that the laser photons have sufficient energy to break the chemical bonds of the rust and paint molecules. For example, the chemical bonds in some organic paint components can be broken by the energy of laser photons, changing the molecular structure of the paint and making it easier to be removed from the surface.

Next, we try to do some comparison between laser cleaning and other conventional cleaning methods. When comparing different cleaning methods, several aspects need to be considered.

In terms of the cleaning method, laser cleaning utilizes a laser in a non-contact manner. In contrast, chemical cleaning employs chemical cleaning agents and is a contact-based process. Mechanical grinding involves the use of machinery or sandpaper, which also requires direct contact with the workpiece. Dry ice cleaning uses dry ice in a non-contact fashion, and ultrasonic cleaning uses cleaning agents and is contact-dependent.

Regarding damage to workpieces, laser cleaning stands out as it causes no damage. However, both chemical cleaning and mechanical grinding can lead to damage. Dry ice cleaning and ultrasonic cleaning, like laser cleaning, do not cause damage to the workpieces.

The cleaning efficiency varies among these methods. Laser cleaning is highly efficient. Chemical cleaning and mechanical grinding have relatively low efficiencies. Dry ice cleaning has a medium efficiency, and ultrasonic cleaning also falls into the medium range.

For consumables, laser cleaning only requires power supply. Chemical cleaning needs chemical cleaning agents. Mechanical grinding uses items such as sandpaper, grinding wheels, and oilstones. Dry ice is the consumable for dry ice cleaning, and ultrasonic cleaning requires special cleaning fluid.

The cleaning effect is another differentiating factor. Laser cleaning offers an excellent result with high cleanliness. Chemical cleaning and mechanical grinding generally have uneven cleaning effects. Dry ice cleaning is excellent but with an uneven finish, and ultrasonic cleaning is excellent though the clean range is small.

Precision in cleaning also differs. Laser cleaning is precise and controllable with high precision. Chemical cleaning is uncontrollable and has poor precision. Mechanical grinding is uncontrollable with average precision. Dry ice cleaning is uncontrollable and has poor precision, and ultrasonic cleaning cannot specify the cleaning range.

In terms of safety and environmental protection, laser cleaning is pollution-free. Chemical cleaning chemically pollutes the environment, and mechanical grinding also pollutes. Dry ice cleaning and ultrasonic cleaning are both pollution-free.

Finally, considering manual operation, laser cleaning has simple operation and can be handheld or automated. Chemical cleaning has a complicated process flow, high operator requirements, and needs pollution prevention measures. Mechanical grinding is labor-intensive and tiring and requires pollution prevention. Dry ice cleaning has simple operation and can be handheld or automated. Ultrasonic cleaning has simple operation but requires manual addition of consumables.

Cost input is also distinct. Laser cleaning has a high initial investment but no consumables and low maintenance cost. Chemical cleaning has a low initial investment but extremely high consumable cost. Mechanical grinding has a high initial investment with low consumable and labor cost. Dry ice cleaning has a medium initial investment and high consumable cost. Ultrasonic cleaning has a low initial investment and medium consumable cost.