How to improve the quality of fiber laser cutting?

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1. Lens inspection

If the cutting head lens is dirty or damaged, it will not only directly affect the quality of cutting, but also further cause the burning of the inside of the cutting head and the laser output head. Careful inspection before cutting is necessary, and the routine inspection and elimination methods are as follows:

Take out the lens to check: before taking out the lens, blow the protective gas for a period of time, seal the nozzle with sealing tape, and quickly seal the opening with sealing tape when pulling out the lens, observe the lens in a bright place to see if there is damage or dirt, if there is, use a dusting cloth or absorbent cotton stick dipped in isopropyl alcohol to wipe and check again. If it cannot be removed, the lens may be damaged, and it is necessary to consider replacing the lens.

Red light inspection method: After the Jepte fiber laser is turned on, the red light indicator is rotated out of the nozzle, and the white cardboard is placed under the cutting head in the appropriate position (about 300mm) to view, if the red light is missing or obvious black spots, the protective lens may be dirty or damaged, and the protective lens needs to be cleaned or replaced. If you ensure that the protective lens is clean and there are still black spots in the red light, you need to further check the collimator and focusing mirror.

2. Actual zero focus

The focus position of laser cutting is a very important data in the cutting process parameters, cutting different thickness and material of the plate, all need to set the appropriate defocusing amount, if the zero focus is inaccurate, will make the actual defocusing amount and the ideal defocusing amount deviation, it will lead to poor cutting effect or even can not cut the plate. Then before cutting, we need to find the actual zero focus of the cutting head so that we can more quickly determine the appropriate defocusing amount corresponding to cutting the plate:

Place a sheet on the machine and set the nozzle height to 0.5mm.

With 0 focal as the basis, positive and negative each adjustment 1mm for a hole or line, and so on, for 15 holes or lines.

Observe the marks of punching and scribing on the thin plate. At this time, the hole aperture or scribing thickness changes with the different defocus amount, and the focus corresponding to the smallest aperture or the thinnest line width is the closest to the actual zero focus.

After finding that the cutting head is closest to zero focus, you can use this zero focus or continue to fine tune as described above.

3, coaxial inspection

The coaxiality of the nozzle exit hole and the laser beam is one of the important factors affecting the cutting quality, if the nozzle and the laser beam are not coaxial, slightly will cause the plate cutting surface effect is poor, coaxial deviation is serious, the laser beam will directly hit the nozzle, causing the nozzle to heat or burn, the following inspection methods:

Nozzle with diameter of 1mm-1.2mm.

Check the shape and cleanliness of the nozzle, the nozzle deformation or slag attachment will directly affect the coaxiality.

The focus of the cutting head is set to zero, the point power and point time can be adjusted according to the actual situation, generally speaking, the point power is inversely proportional to the point time, the larger the point power, the smaller the point time.

Take a piece of scotch tape and attach it to the end face of the nozzle outlet

Click the laser light button and release immediately

Take off the tape and look at the tape mark, (be careful not to turn the direction when taking off the tape), look at the tape mark, there is a circle of aperture size on the mark, and observe whether the spot is in the center of the nozzle circle.

If the center of the nozzle deviates too much from the center of the laser beam, it will not be able to see the burning point (the laser beam is emitted to the nozzle wall), at this time, a nozzle with a slightly larger diameter should be selected to adjust the beam to the center of the nozzle, and then a small-caliber nozzle should be used to further adjust.

Pay attention to the direction of the burning point deviating from the center of the nozzle, adjust the center fine adjustment screw, so that the laser beam and the nozzle are coaxial. If higher coaxiality is required, a smaller nozzle can be used for further adjustment.

If the center point is large or small, pay attention to whether the shooting conditions are consistent. If the shooting conditions are consistent, check whether the focusing mirror is loose. When the coaxiality is adjusted at the zero focus, the coaxiality is found to change after defocusing, and it is necessary to check whether the collimating focusing mirror is loose.

4. Spot inspection

The distribution of the spot will affect the cutting effect, and the continuous fiber laser has a good spot distribution, which can ensure the consistency of the cutting surface finish and cutting speed in all directions. The steps to check the spot are as follows:

The point frequency is set to 1Hz, the point power is set to 100%, and the best spot time (adjust duty cycle) is set according to the power of the laser.

According to the lens combination of the cutting head, set the appropriate spot distance (if the focusing F=200mm, you need to place the photo paper more than 200mm away from the cutting head), and point the light.

Observe the distribution of light spots on the photo paper. If there are obvious black spots in the light spots, the lens is dirty.

If the spot is not round and the center is offset, the spot distribution is poor. If the light spot is missing, the light blocking situation may occur.

5, nozzle heating range

High power cutting often encounters the problem of nozzle heating, you can test the heating of different caliber nozzles at different focal points, the inspection steps are as follows:

Adjust the coaxial and install the cooling air.

Full power light (high power laser light 10s, low power laser light 20s), check whether the nozzle heat. Change the focus position, continue the test as described above, and record the focus of nozzle heating.

Replace the nozzle with a different caliber and repeat the above test steps.

The summary of the heating conditions of different diameter nozzles can provide reference for the subsequent cutting process adjustment.

6. Other checks

In addition to the above items that directly affect the cutting effect and efficiency in the cutting process need to be checked, in order to keep the laser cutting equipment to maintain efficient and stable work for a long time, the following items should also be checked before use:

Gas: The cutting machine needs to detect the pressure of the gas before starting, if the gas pressure is not enough to adjust the gas valve, if the gas pressure is still not enough after adjusting the gas valve, it is necessary to replenish the gas in time.

Cooling equipment: check whether the water cooler works normally. In winter, if the temperature is too low, antifreeze should be added to prevent icing from affecting the normal operation of the water cooler. At the same time, check whether the air-conditioned room can meet the requirements of constant temperature and humidity in the room.

Pipeline inspection: Check whether there is leakage of the gas pipe and water pipe. If there is, replace the pipeline in time.

Safety system: The detection of the safety system should be more focused on detection before use, and the continuous fiber laser can be monitored and alerted to the operating status of the laser in real time through the control interface and the standard software of Jeput, and the operation data can be collected and recorded.

The above is about how to improve the quality of fiber laser cutting machine knowledge, if you want to get more knowledge about laser cutting, you can visit the laser forum, in the laser forum, you can find more answers to questions, but also for others to provide solutions, you can also download free laser cutting material.