Laser cleaning is an eco-friendly process used to remove rust, paint, oxide and other contaminants from metal surfaces. Because of its efficiency, it is being used in an increasing number of applications. Laser cleaning requires a pulsed fiber laser (typically 50 watts or more).

Traditional industrial cleaning methods are often seen as tedious (and for good reasons). Rust removal can be time and labor consuming. Oxide removal may involve hazardous chemicals specific to each material that needs to be removed. In some cases, paint removal by sandblasting can damage the metal underneath.

Dealing with these problems usually comes at a significant cost, but laser cleaning is changing this: it is a cost-effective solution that reduces cleaning times and maintenance.

If you are skeptical about these claims regarding laser technology, keep reading for the key facts about what a laser does when removing contaminants and coatings.

Essentially, laser cleaning is laser ablation applied to some kind of unwanted substances on some workpiece. Usually, the hit material exhibits substantial absorption of the incident intense laser light. The highly localized conversion of optical energy to heat leads to a very rapid temperature rise and consequently to evaporation of the material – possibly also involving partial or complete chemical destruction of the material. The strong temperature gradient resulting from the localized heating creates substantial mechanical stress which often supports the removal process.

The laser radiation often needs to be tightly focused to the surface of the target area, because the required ablation process works only above a certain intensity threshold. Cleaning may be possible with relatively low average power, but then requires tight focusing, which in turn leads to longer processing times. If a higher laser power is available, one may use a beam shape which is much elongated in one direction in order to clean a correspondingly wider stripe in one go. Often, the laser beam is systematically moved over the surface to be cleaned, covering the relevant area with a suitable pattern.

The laser radiation often needs to be tightly focused to the surface of the target area, because the required ablation process works only above a certain intensity threshold. Cleaning may be possible with relatively low average power, but then requires tight focusing, which in turn leads to longer processing times. If a higher laser power is available, one may use a beam shape which is much elongated in one direction in order to clean a correspondingly wider stripe in one go. Often, the laser beam is systematically moved over the surface to be cleaned, covering the relevant area with a suitable pattern.

In many cases, one exploits substantially stronger absorption in the material to be removed, compared with the less absorbing substrate material which is supposed to remain. One may then exceed the intensity threshold for ablation of the dirt while not reaching it for the substrate material. It can further be helpful that the substrate material is often more robust in other ways, e.g. concerning hardness or thermal conductivity.

Sometimes, additional selectivity may be introduced by so tightly focusing a laser beam that the intensity rapidly decreases for longitudinal positions behind the beam focus. Shallow beam incidence can then also help.

Beam parameters like wavelength, average power, focus beam diameter etc. may need to be adjusted when applying the cleaning process to other circumstances.

It is common to apply pulsed lasers with nanosecond or even shorter pulse durations for cleaning purposes, because compared with continuous-wave operation this leads to a lower heat load on the cleaned material (“cold ablation”). A high pulse repetition rate is usually wanted for a high enough processing speed. Pulsed fiber lasers and more conventional Q-switched solid-state lasers are often used. In some cases, one uses an excimer laser, because the ultraviolet light is particularly well absorbed in some materials.

Some continuous-wave high-power lasers are also used. For example, direct diode lasers are attractive because of their high wall-plug efficiency and relatively low installation cost, despite their very limited potential for pulse generation. CO₂ lasers, partly in continuous-wave operation, are also still in use. One of their advantages is the lower risk for the eyes .

Traditional laser machines have some limitations, such as cleaning with chemical solvents, using media blasting, which is very abrasive, dry ice blasting, and causing severe environmental pollution. But to solve this, there was a need for a modernized equipment technology. With that said, let look at its advantages;

• Eco-Friendly

The process does not use harmful products that might harm the environment, such as solvents, acids, or toxic chemicals. This reduces the risk of contamination or exposure of employees to dangerous materials. There are also no exhaust emissions, and all residues are recycled, and low noise is produced.

• Contact Free / Non-Abrasive

Laser cleaning removes impurities from the surface of an object without touching the underlying material as no chemicals are used, and no mechanical or thermal strain is placed on it. Thus, unnecessary wear is not caused; hence the quality of content is not degraded.

• Online Automation

It puts the worker far away from the operation as it requires very little input from an operator; hence the element of safety is maintained. Due to its automatic nature, operations can be run fast with a high degree of accuracy, making the technology reliable and has excellent power output, pulse parameters, and wavelengths. This results to lower costs compared to other cleaning systems.

• Spatially Selective

The cleaning process is straightforward as the machines can clean various types of contaminants to achieve cleanliness. Its small spot size focuses on the preferred area and ignores all locations that do not require cleaning, therefore saving on time.

• Cleaning of Micro-Application

The laser cleaning machine can clean organic contaminants and inorganic materials like metal corrosion, dust, and metal particles. It can be achieved through a long-distance operation. It can easily clean sites that traditional cleaning systems can’t reach. This is important as it is used in dangerous places to ensure the safety of the personnel.

• Cost Saving

Although the purchase price is quite an investment, you can use the machine for an extended period without having to buy another one. The maintenance and operation

The cost is low and favorable to companies or individuals.

Laser cleaning is used under quite different circumstances; the most important laser cleaning applications are explained in the following.

Cleaning of Industrial Workpieces in Factories

Gas and Oil Pipelines

Aerospace and Ships

Preparation of Sensitive Processes

Restoration of Artworks