Laser Treatment Method for Rust on Metal Products Before Welding-ShangHai RunQia Electronics Technology Co.,Ltd.

Laser Treatment Method for Rust on Metal Products Before Welding

The RQM series laser cleaning equipment is specially developed to solve the technical difficulty that dense oxide layers formed on metals after high-temperature heat treatment or welding are difficult to remove by conventional cleaning methods. Metal products such as copper, carbon steel and stainless steel manufactured under high-temperature working conditions are all covered with a dense oxide layer.

The laser cleaning equipment developed and manufactured by Shanghai Runqia features excellent and efficient cleaning performance on high-temperature scale, copper oxide and iron rust. It adopts laser shock waves to gasify surface contaminants. The operation produces no smoke or odor, making it an ideal environmentally friendly solution. It can improve production efficiency, simplify technical procedures and significantly reduce comprehensive costs.

I. Process Scope

Pulsed TEA-CO₂ laser: 10.6 μm

Pulsed laser: 1.06 μm

Principle of Laser Surface Cleaning

Pulsed laser cleaning relies on the characteristics of laser pulses generated by the laser source. It is based on the photophysical reaction produced by the interaction between high-intensity beam, short-pulse laser and contamination layer. The physical mechanism is summarized as follows:a) The laser beam emitted by the laser is absorbed by the contamination layer on the surface to be treated.b) High energy absorption generates rapidly expanding plasma (highly ionized unstable gas) and produces shock waves.c) The shock wave breaks contaminants into fragments and removes them from the surface.d) The laser pulse width must be sufficiently short to avoid thermal accumulation that would damage the substrate surface.e) Experiments show that plasma is generated directly on the metal surface when oxides exist.

Plasma is only generated when the laser energy density exceeds a threshold value, which depends on the contamination or oxide layer to be removed. This threshold effect is critical for effective cleaning while ensuring the safety of the base material. There is a second threshold for plasma generation; if the energy density exceeds this limit, the substrate material will be damaged. To achieve efficient cleaning without damaging the substrate, laser parameters must be adjusted properly to keep the energy density of laser pulses strictly between the two thresholds.

II. Treatment Methods

1.Small workpieces can be cleaned automatically; the specific cleaning time depends on the thickness of the oxide scale and shall be verified through actual production tests.

2.For large workpieces, a customized sliding rail platform can be adopted for cleaning operation.

3.For complex structural parts of workpieces, handheld laser cleaning is available.

III. Equipment Management and Maintenance

1.The equipment shall be operated in an enclosed space with specific environmental requirements.

2.The focal length shall be adjusted timely when cleaning workpieces of different sizes.

3.Laser parameters shall be set and operated in strict accordance with the equipment manual; parameter values shall not exceed the maximum limit to avoid safety accidents.

4.Stable power supply must be guaranteed during equipment operation.

IV. Labor Protection

Operators must wear labor protection supplies such as laser protective goggles and protective gloves to ensure personal safety.

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