Laser cutting blanking requires two steps - piercing and cutting. Only by ensuring a good and stable piercing effect can cutting be achieved. When thick plates are perforated, holes are easy to burst, resulting in unstable cutting, damaged lenses and nozzles, etc. Therefore, excellent piercing is the first step to obtain good sample effect while stable processing.

Pulse perforation mode

Optical fiber laser cutting generally adopts the pulse laser mode of peak power to melt a small amount of materials. Carbon steel cutting usually uses oxygen as the auxiliary gas. Each pulse laser will produce smaller particles to spray and gradually penetrate, so that the perforation diameter is smaller, the spraying slag is less, and the cutting start is more stable. The pulse perforation mode must have a good gas path control system to achieve fine control of gas type and gas pressure.

Laser parameters of pulse piercing

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

Cause of hole explosion

In the process of perforation, hole bursting is often encountered, as shown in the figure below when 30mm carbon steel is perforated, which may be caused by the following reasons:

1. The pulse duty cycle is large;

2. The perforation air pressure is set too high;

3. Piercing pulse frequency is too high;

4. Between multistage perforations, light blowing or blowing time is too short;

Solution to hole blasting

1. Large pulse duty ratio:

2. The perforation air pressure is set too high:

3. Piercing pulse frequency is too high:

Piercing method guidance:

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

2. Under the premise of ensuring that the laser spot will not hit the nozzle, the perforation focus will be appropriately reduced;

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

4. Stop light blowing is added between multistage perforations, which is not easy to explode.