[Cutting Skills] How to overcome the problem of explosion of 10,000-watt laser perforation?

Laser cutting requires two steps: perforation and cutting. Cutting can only be achieved if a good and stable perforation effect is ensured.

When punching thick plates, it is easy to have holes burst, which will cause unstable cutting, damage to lenses and nozzles, etc. Therefore, in order to obtain stable processing and good sample results, excellent punching is the first step.

Pulse punching method

Fiber laser cutting generally uses a high peak power pulse laser to melt a small amount of material. Carbon steel cutting often uses oxygen as an auxiliary gas. Each pulse laser will produce a small particle spray and gradually penetrate deeper, so that the perforation diameter is smaller, less slag is sprayed, and the cutting start is smoother. The pulse perforation method requires a better gas path control system to achieve fine control of gas type and gas pressure.

Pulse perforation laser parameters

Pulse period: T = 1/frequency, pulse width: t = T * duty cycle

For example, Figure 1: Pulse frequency 500HZ, duty cycle 50%

It can be obtained that: pulse period T = 1/500 = 2ms, pulse width t = 2*50% = 1ms

Causes of explosion

During the perforation process, the phenomenon of hole bursting is often encountered. As shown in the figure below, a hole burst occurs when perforating 30mm carbon steel. The possible reasons are as follows:

1. The pulse duty cycle is relatively large;

2. The perforation air pressure is set too high;

3. The perforation pulse frequency is too high;

4. There is no light stopping and air blowing between multi-stage perforations, or the air blowing time is too short;

Normal effect of perforation▲

Explosion hole effect picture▲

Explosion hole solution

1. The pulse duty ratio is relatively large:

Before optimization▲ After optimization▲

2. The perforation air pressure is set too high:

Before optimization▲ After optimization▲

3. The perforation pulse frequency is too high:

Before optimization▲ After optimization▲

Piercing method guide:

1. The peak power is as high as possible to improve the perforation efficiency;

2. Ensure that the laser spot does not hit the nozzle, and lower the perforation focus appropriately;

3. The oxygen perforation pressure is equivalent to the cutting pressure;

4. Stop the light and blow air between multi-level perforations to prevent holes from bursting.