Laser cleaning technology uses high-frequency and high-energy laser pulses to irradiate the surface of the workpiece. The coating layer can instantly absorb the focused laser energy, so that the oil stains, rust spots or coatings on the surface can be evaporated or peeled instantly, and the surface attachments or surface coatings can be effectively removed at a high speed. The laser cleaning method, and the laser pulse with a short action time, will not damage the metal substrate under the appropriate parameters.

Principle:The cleaning process of pulsed Nd:YAG laser relies on the characteristics of the light pulse generated by the laser, based on the photophysical reaction caused by the interaction between the high-intensity beam, the short-pulse laser, and the pollution layer.

The physical principles can be summarized as follows:

1.The beam emitted by the laser is absorbed by the pollution layer on the surface to be treated;

2.The absorption of large energy forms a rapidly expanding plasma (a highly ionized unstable gas), which produces shock waves;

3.The shock wave turns pollutants into fragments and is removed;

4.The light pulse width must be short enough to avoid heat accumulation that damages the surface to be processed;

5. Experiments show that when there are oxides on the metal surface, plasma is generated on the metal surface.

Plasma is only generated when the energy density is higher than the threshold, which depends on the contamination layer or oxide layer being removed. This threshold effect is very important for effective cleaning while ensuring the safety of the base material. There is a second threshold for the appearance of plasma. If the energy density exceeds this threshold, the base material will be destroyed. In order to perform effective cleaning under the premise of ensuring the safety of the base material, the laser parameters must be adjusted according to the situation so that the energy density of the light pulse is strictly between the two thresholds.

Each laser pulse removes a certain thickness of contamination layer. If the contamination layer is relatively thick, multiple pulses are required for cleaning. The number of pulses required to clean the surface depends on the degree of surface contamination. An important result produced by the two thresholds is the self-control of cleaning. The light pulse whose energy density is higher than the first threshold will keep out contaminants until it reaches the base material. However, because its energy density is lower than the destruction threshold of the base material, the base will not be damaged.

Nd: YAG devices have been widely used in material processing. In addition to laser drilling, welding, heat treatment, marking, writing, dynamic balancing and other processing applications, it can also be widely used in the field of micro processing. Especially the processing of large-scale integrated circuits has shown its unique advantages.

Jinan Gold Mark CNC Machinery Co., Ltd. is a high-tech industry enterprise specialized in researching, manufacturing and selling the machines as follows: Laser Engraver, Fiber Laser Marking Machine, CNC Router. The products have been widely used in advertisement board, crafts and molding, architecture, seal, label, woodcutting and engraving, stonework decoration, leather cutting, garment industries, and so on. On the base of absorbing the international advanced technology, we provide the clients the most advanced production and perfect after-sale service. In recently years, our products have been sold not only in China, but also as far as Southeast Asia, Middle east, Europe, South America and other overseas Markets.

Email:   cathy@goldmarklaser.com

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