Six common problems and solutions of fiber laser cutting machine
1、 Laser equipment cutting and perforation technology
In the hot cutting process, except for a few cases where cutting can be done directly from the edge of the sheet, it is usually necessary to drill a starting hole in advance on the sheet. For fiber laser cutting machines without stamping devices, the following two perforation methods are mainly used:
- Pulse Perforation
Principle: Using high peak power pulsed laser to melt or vaporize a small amount of material. Air or nitrogen is commonly used as an auxiliary gas, with a pressure lower than the oxygen pressure during cutting, to reduce the pore size expansion caused by exothermic oxidation. Each pulse produces only tiny particle jets that gradually penetrate into the material.
Characteristics:
The perforation diameter is smaller and the quality is better than explosive perforation.
The perforation time for thick plates is relatively long, usually taking a few seconds.
High requirements are placed on lasers, requiring high output power and good beam time and spatial characteristics.
A reliable gas path control system is required to achieve precise control of gas type, pressure switching, and perforation time.
Transition technology optimization: When transitioning from static pulse perforation to constant speed continuous cutting, in order to obtain high-quality incisions, industrial production mainly achieves a smooth transition by changing the average laser power. The specific methods include changing the pulse width, changing the pulse frequency, or changing both simultaneously. Practice has shown that changing both pulse width and frequency simultaneously yields the best results.
- Explosion Perforation
Principle: After continuous laser irradiation, a pit is formed in the center of the material, and then the molten material is quickly removed by an oxygen flow coaxial with the laser beam, forming a hole.
Characteristics:
The aperture size is related to the plate thickness, with an average diameter of about half the plate thickness.
The perforation holes of thicker plates are larger and have a non-circular shape, resulting in larger splashes.
Not suitable for parts with high machining accuracy requirements, usually only used for waste or non critical areas.
The oxygen pressure used for perforation is the same as that used for cutting.
2、 Analysis of deformation of small holes in cutting and processing
This problem mainly occurs when high-power laser cutting machines process small holes with a diameter smaller than the plate thickness.
Cause analysis: If the machine tool uses pulse perforation (soft puncture) when processing small holes, the laser energy is too concentrated in a small area, causing the non processing area to be burnt, resulting in deformation of the hole shape and affecting the processing quality.
Solution:
High power laser machine: Change pulse perforation (soft puncture) to explosive perforation (ordinary puncture) in the processing program.
Low power laser machine: On the contrary, pulse perforation should be adopted to achieve better surface smoothness.
3、 Solution to burrs on workpieces during laser cutting of low-carbon steel
According to the working principle of laser cutting, the main causes and countermeasures of burrs are as follows:
Incorrect focus position: Conduct a focus position test and adjust the up and down positions based on the offset.
Insufficient laser output power: Check if the laser generator is working properly; If normal, check the output value of the control button and adjust it accordingly.
Cutting line speed too slow: Increase the line speed appropriately in the operation control.
Insufficient purity of cutting gas: Provide high-quality cutting working gas.
Laser focus offset: Re test and adjust the focus position.
Unstable operation of the machine tool: If the machine tool runs for too long and becomes unstable, it needs to be shut down and restarted.
4、 Analysis of workpiece burrs generated during laser cutting of stainless steel and aluminum zinc coated plates
Difficulty: When burrs appear on such materials, it cannot be simply solved by increasing the cutting speed, as too fast a speed may cause the sheet to be difficult to cut through, especially when processing aluminum zinc coated sheets.
Solution: It is necessary to comprehensively consider other factors of the machine tool, such as checking whether the nozzle needs to be replaced and whether the guide rail movement is stable, and conduct systematic investigation and adjustment.
5、 Analysis of incomplete laser cutting through state
The main reasons for unstable processing leading to incomplete cutting include:
Improper nozzle selection: The selection of the laser head nozzle does not match the thickness of the processing plate.
Cutting speed too fast: Need to control and reduce the line speed.
Large error in focus position: Inaccurate nozzle sensing leads to excessive deviation in laser focus position, requiring retesting of nozzle sensing data (this problem is most likely to occur when cutting aluminum).
6、 Solution to abnormal sparks when cutting low carbon steel
Abnormal sparks can affect the smoothness of the cutting surface of parts. When other parameters are normal, the following aspects should be checked:
Nozzle wear: The laser head nozzle (NOZZEL) is worn and should be replaced in a timely manner. If there is no new nozzle, the cutting gas pressure can be temporarily increased.
Loose connection: The thread at the connection between the nozzle and the laser head is loose. At this point, cutting should be immediately paused, the connection status of the laser head should be checked, and the threads should be tightened again.