The defocus amount is an important parameter that affects the cutting quality in the laser cutting process. In the oxygen-free cutting of stainless steel plates, auxiliary gas is used to blow away the molten residue to reduce the amount of slag. Cutting quality is very important. Therefore, it is necessary to set the focus position inside the steel plate to expand the cutting width to achieve the purpose of increasing auxiliary gas flow

What is the relationship between the defocus amount of laser cutting and the slag and burrs generated during the cutting process

The selection of defocus amount has a significant impact on the cutting quality of stainless steel plate:

【1】 When the focal point position is appropriate, the slit material melts, but the material near the cutting edge does not melt, and the slag is blown away, forming a clean and free slit.

【2】 When the focal point position lags behind, the energy absorbed per unit area of the lower part of the cutting material decreases, resulting in a weakening of the cutting energy, which causes the material to not completely melt and be blown away by the auxiliary gas, so that the incompletely melted material adheres to the lower surface of the cutting plate.

【3】 When the focal point position is advanced, the average energy absorbed per unit area in the lower half of the cutting material increases, resulting in the material being cut melting with the material near the cutting edge and becoming liquid flowing. At this time, due to the constant auxiliary air pressure and cutting speed, the melted material adheres to the lower surface of the material in a spherical shape and forms slag.

In practical production, laser cutting of stainless steel plates requires the focus to be selected on or below the surface of the material. This is because the width of the upper part of the cutting groove is enlarged, the fluidity of gas and molten substances is improved, and the smooth range of the cross section is expanded, improving the cutting quality.

During the cutting process, the focus position is also not fixed for steel plates of different thicknesses. When the focus position is taken on or above the surface of the steel plate, due to the low average power density and insufficient energy at the bottom of the steel plate, it is easy to generate slag on the lower surface. Therefore, when laser cutting stainless steel plates, the focus position should be selected within the material. To improve the fluidity of gas and molten metal, ensure sufficient energy density at the lower part, and expand the range of the smooth surface.