Select the correct focus position and cut out a high-quality metal sheet

Different focal positions often result in different degrees of delicateness of the cutting material, different slag hanging on the bottom, and even the material cannot be cut; the cutting workpiece is different, and the distance between the laser focus and the cutting material must be adjusted before cutting any material. . Different, the position of the focus of the fiber cutting machine will be different, so how to choose correctly?

Definition of focus position: The distance from the focus to the upper surface of the cutting workpiece. The focus position above the workpiece is generally called the positive focus, and the focus position below the workpiece is generally called the negative focus.

Significance of focus position: Changing the focus position means changing the spot size on the surface and inside of the board, the focal length becomes larger, the spot becomes thicker, the slit becomes wider and wider, and the slenderness affects the heating area, slit size and slag discharge .

Positive focus cutting

For carbon steel oxygen cutting, adopting a positive focus, the bottom ratio of the workpiece, and the cutting width of the upper surface are conducive to slag discharge, and it is beneficial for oxygen to reach the bottom of the workpiece to participate in the full oxidation reaction. Within a certain focus range, the size of the positive focus, the size of the spot on the board surface, the pre-heating around the slit and the replacement and supplementation are more sufficient, the smoother and brighter the carbon steel cutting surface is. This method uses stainless steel to cut thick stainless steel plate with positive focus, stable cutting, good for slag discharge and difficult to reflect blue light.

Negative focus cutting

That is, the cutting focus is in the workpiece. In this mode, because the focal distance is from the cutting surface, the cutting width is relatively larger than the cutting point on the workpiece surface. At the same time, the cutting airflow is large and the temperature is sufficient. When cutting stainless steel, negative focus cutting is adopted, and the cutting surface is evenly textured.

The perforation of the plate before cutting, because the perforation has a certain height, the perforation uses a negative focus, which can ensure that the spot size at the perforation position is the smallest, the energy density is the largest, and the deeper the perforation position, the negative focus is reduced.

Zero focus cutting

That is, the cutting focus is on the surface of the workpiece. Generally, the cutting surface close to the focus is relatively smooth, and the lower surface from the cutting focus is gradually rough. This condition is mainly used for continuous laser cutting of thin plates and pulse lasers for high-wavelength power vaporization to cut metal foil layers.