The burr generated when laser cutting sheet metal is a common process problem, which usually indicates that the cutting process is not optimal. To solve this problem systematically, it is necessary to check and adjust from multiple dimensions such as equipment, materials, process parameters and auxiliary gases.
Core optimization direction and specific measures
1. Optimize process parameters (for carbon steel and other materials)
- Laser power: insufficient power is one of the main causes of burrs. Appropriately increasing the power can ensure that the metal is fully melted. However, it should be noted that too high power may cause the plate to burn or hang slag.
- Cutting speed: The speed is too fast, the laser energy input is insufficient, the material is not completely melted, and it will be blown into burrs by the airflow; if the speed is too slow, the burning will be serious and the slag will adhere. Adjust to the best speed that matches the power and plate thickness. You can usually test the parameters first. Focus position: Incorrect focus will result in insufficient energy density. Focus test to find the most suitable position for the current plate thickness (usually when cutting carbon steel, the focus is on the surface of the plate or slightly below).
2. Ensure that the auxiliary gas is in the best condition (the most critical factor)
- Gas type and purity:
- Cutting carbon steel: High purity oxygen (≥ 99.95%) must be used. Oxygen participates in the exothermic reaction, helping to burn and blowing away the slag. Insufficient purity will greatly affect the cutting quality and section oxide layer.
Cutting stainless steel and aluminum: high-purity nitrogen (≥ 99.99%) or argon should be used. Use high-pressure gas to blow away molten metal to achieve oxidation-free cutting. The impure gas will cause slag on the bottom.
- Gas pressure:
- Cutting carbon steel (with oxygen): the pressure should not be too high (usually 0.8-2bar). Excessive pressure will cool the incision, but reduce the efficiency of the combustion reaction, the formation of burrs.
- Cutting stainless steel/aluminum (with nitrogen): The pressure must be high enough (usually 10-20 bar, depending on the plate thickness). Insufficient pressure is the most common cause of burr-free cutting failure, and the molten metal cannot be completely blown away.
- Nozzle status:
- Check to make sure that the nozzle is not damaged or blocked by spatter. A worn nozzle can cause turbulence in the air flow.
- Check whether the nozzle hole diameter matches the plate thickness and gas pressure. Thick plates usually require larger orifice nozzles.
- Calibrate the concentricity of the nozzle and the laser head. The concentricity deviation will cause the gas to blow and produce burrs on one side.
3. Check and maintain equipment status
- Optical lens cleaning: protection mirror, focusing mirror pollution will greatly reduce the laser power and beam quality. Regularly check and clean or replace the lenses.
- Beam quality: regular beam calibration to ensure that the optical path is correct and the focus is rounded.
- Equipment stability: Check whether the machine tool guide rail and transmission system are stable, and irregular burrs will be generated when shaking at high speed.
4. Focus on the material itself
- Sheet surface: Ensure that the surface of the sheet is free of serious rust, paint or coating, which will affect the laser absorption and cutting stability.
- Material composition and quality: poor quality or uneven alloy composition of the plate may also lead to fluctuations in the cutting effect.
Special Concerns for Burr Problems in Different Materials
- Carbon steel plate (oxygen cutting): the bottom burr is mostly hard and brittle iron oxide slag. Mainly from the oxygen purity, focus position, power speed matching.
- Stainless steel aluminum plate (nitrogen cutting): the bottom burrs are mostly soft and long unblown molten metal. The first task is to check whether the nitrogen pressure is high enough, whether the gas is pure, and whether the nozzle is suitable.
Systematic resolution process recommendations
1. Record and reproduce: record the current burr plate type, thickness, and all process parameters (power, speed, air pressure, focus, nozzle type) in detail.
2. Single variable adjustment: adjust only one parameter at a time (it is recommended to start with gas pressure and focus position first) for trial cut comparison.
3. From simple to complex troubleshooting:
- Step 1: Check and clean the nozzle and lens.
- Step 2: Check the gas purity and pressure.
- Step 3: Optimize the focus position.
- Step 4: Adjust the matching of power and speed.
- Step 5: calibrate the optical path and concentricity of the device.
4. Establish a standard parameter library: once the best parameters are found for plates of different brands, thicknesses and materials, they will be recorded to form standard operating instructions.
Summary: The core of solving the problem of laser cutting burrs is to “ensure sufficient energy input, and cooperate with a stable, pure, and correct direction of airflow to blow the melt away in time”. It is a systematic problem that requires the operator to have patience and gradually investigate and optimize through scientific methods. If all the above steps are checked and the problem persists after adjustment, you need to contact the equipment manufacturer to check whether the laser output energy or beam mode has changed.