Laser Cleaning Machine Application Cases

Laser Cleaning Basic Principles

When a high-energy laser beam irradiates the surface of a workpiece, the photon energy is absorbed by the material and converted into thermal energy, causing the surface material to rapidly heat up to melt or even vaporize, resulting in micro-explosive peeling.

 

 

Ultra-high peak value, short pulse laser acts on the workpiece, and the surface dirt, rust or coating absorbs the laser and evaporates or peels off instantly, while the substrate hardly absorbs the laser, achieving the effect of removing surface dirt without damaging the substrate.

Surface material absorb laser→Physical and chemical reaction→Remove of the product→Cleaned surface reflect laser

 

 

Laser cleaning features

However,laser cleaning can solve these problems

 

Environment protecting- no chemical reagents, no solvents, low noise

Convenient operation--non-contact processing, portable and movable operation

No damage - only surface contaminants are removed

Easy to automate - convenient for integration and high efficiency

Maintenance-free, low operating costs - laser cleaning equipment has no wearing parts

Selective operation - spot cleaning of local areas

What is single-mode and multi-mode

Single-mode refers to the situation where a laser generates only one mode of laser output during operation. The energy intensity of a single mode gradually weakens from the center to the outer edge, and the energy distribution form is a Gaussian curve. Its beam is called a fundamental mode Gaussian beam. The laser beam output by single-mode has the characteristics of high beam quality, small beam diameter, small divergence Angle, and energy distribution close to the ideal Gaussian curve. In addition, the single-mode has good focusing characteristics, with a small focused spot and strong mode stability, making it suitable for cleaning scenarios that require strong removal, such as rust.

Figure shows the energy distribution of a single mode

The spot output by a multimode laser is often composed of multiple modes. The energy distribution within the spot is relatively uniform, and the more modes there are, the more uniform the energy distribution. Its beam is also called a flat-top beam. Compared with single-mode lasers, multimode lasers have poorer beam quality, larger divergence angles, require an optical system with a larger aperture for transmission, and have a larger focused spot than single-mode lasers. However, multimode is relatively easy to achieve large single-pulse energy, peak power and high average power output, and the energy distribution is uniform. It has more advantages in scenarios where cleaning requires less damage and high efficiency, such as molds.

 Figure shows the multimode energy distribution diagram

 

The difference between single-mode and multi-mode

Single-mode lasers, due to their excellent beam quality, small focused spot size and high energy density, are suitable for removing strongly adhesive contaminants such as green rust, and are also applicable for cleaning thin materials and precision parts that are sensitive to heat input. However, due to the excessive concentration of single-mode energy, certain damage may be caused to the substrate material during cleaning.

For scenarios such as molds where the base material is required to remain undamaged after cleaning, multimode lasers must be selected. The energy distribution of multimode beams is uniform and the peak power is high. The peak power density can be controlled to be higher than the damage threshold of contaminants and lower than that of the substrate. Therefore, during cleaning, contaminants can be effectively removed without damaging the structure of the material surface. In addition, the focused spot of multimode is larger. For scenarios where single-mode and multimode can achieve the same cleaning effect, the cleaning efficiency of multimode is usually higher. However, for strongly adhering contaminants, multimode laser cleaning may be inadequate.

Mode	Beam characteristics	Cleaning ability	Cleaning efficiency	Substrate damage	Application scenarios
Single mode	High energy density	Strong	Moderate	Yes	Rust removal, etc.
Multi-mode	Uniform energy distribution	Moderate	High	No/slight	Mold, etc.

The table shows the differences between single-mode and multi-mode

 

 

 

 

Typical application cases of laser cleaning

1.Typical application cases of single-mode laser cleaning

 

 

2.Typical application cases of multi-mode laser cleaning