Laser Treatment Method for Metal Scale and Weld Spots-ShangHai RunQia Electronics Technology Co.,Ltd.

Laser Treatment Method for Metal Scale and Weld Spots

Steel surfaces are usually covered with a layer of scale and rust. Scale is an oxide formed when steel comes into contact with air at high temperatures during the rolling process. It is grayish-black and covers the steel surface. The rust layer is a yellow substance containing oxides and water molecules, which also adheres to the steel surface. Both scale and rust cause great harm to steel. Severe scale and rust can reduce the bearing capacity of structural components. Structural parts such as crane beams and columns are generally about 6–10 mm thick, and the cross-sectional weakening caused by scale and rust cannot be ignored.

The presence of oxides and rust on steel structures deteriorates the painting quality. If paint is sprayed directly onto scale or rust, the bonding between scale and the steel substrate is extremely weak. Elastic deformation, thermal expansion and contraction, collision and other stresses on load-bearing components will cause the scale and rust to peel off, taking the paint layer along and resulting in loss of protective performance.

Traditional cleaning methods such as pickling, shot blasting and sandpaper grinding have become outdated. These methods not only pollute the environment, but also feature low efficiency, high labor and time consumption, leading to a waste of human resources.

The laser cleaning equipment developed and manufactured by Shanghai Runqia delivers excellent and efficient cleaning performance on high-temperature scale, copper oxide and iron rust. It uses laser shock waves to gasify surface contaminants. The working process produces no smoke or odor, making it an ideal environmentally friendly solution. It can improve production efficiency, simplify manufacturing processes and greatly reduce overall costs.

Core Functions

Oil removal, rust removal and multi-functional integrated performance. The operation process is extremely simple; operators can master the entire workflow within 3–5 minutes and become proficient in one hour. It features simplicity, high speed, low cost and environmental friendliness.

Principle of Laser Surface Cleaning

The cleaning process of pulsed Nd:YAG laser relies on the characteristics of optical pulses generated by the laser. It is based on the photophysical reaction caused 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 forms rapidly expanding plasma (highly ionized unstable gas) and generates shock waves.c) The shock wave breaks contaminants into fragments and removes them from the surface.d) The optical pulse width must be sufficiently short to avoid thermal accumulation that would damage the substrate surface.e) Experiments show that plasma generates on the metal surface when oxides exist.

Plasma is only generated when the 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 to keep the energy density of optical pulses strictly between the two thresholds.

Advantages of Laser Cleaning

1）Non-contact surface cleaning relying solely on laser, with no additional medium required

2）Low production cost and fast investment return

3）No damage to the base material

4）Environmentally pollution-free

5）Precisely controllable processing with high product quality

6）High processing efficiency

7）Low noise operation

8）Easy automation and integration into existing processes and production lines; minimal maintenance requirements

Application Fields

Laser cleaning machines are widely used for bright finishing and cleaning of various stainless steel materials. It can remove oil stains, rust, scale, weld spots and other contaminants, restoring the original metallic luster of stainless steel after treatment.

Operation Process

1)Small workpieces can be cleaned automatically; the specific cleaning time depends on the thickness of the scale and shall be tested on-site during production.

2)Large workpieces can be cleaned with a customized sliding rail platform system.

3)Complex structural parts of workpieces can be cleaned by handheld laser operation.

The above is the detailed introduction of laser cleaning machine for oxide layer removal, provided by Shanghai Runqia Electronic Technology Co., Ltd. Please contact our company if you have any inquiries.

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