How do I use a laser welding machine?

How do I use a laser welding machine?

At this stage, the manufacturing, automotive and eyewear industries have a partial demand for laser welding machines. How much do you know about the common technical parameters debugging, operating directions and processes in the use of laser welding machines?

First we learn about the main parameters of laser welding machines

1. Laser power density

Power density is one of the most critical parameters in laser processing. Having a higher power density allows the surface layer to be heated to the boiling point within a time frame of microseconds, resulting in a large amount of vapourisation. High power densities therefore facilitate material removal processes such as stamping, cutting and engraving. For lower power densities, the surface temperature takes a few milliseconds to reach the boiling point. The bottom layer reaches the melting point before the surface layer vaporises, which makes it easy to form a good fusion weld. Therefore, in conductive laser welding, the power density is in the range of 104 to 106 W/cm2.

The beam spot size is one of the most important variables in laser welding, as it determines the power density. However, its measurement is a challenge for high power lasers, although there are many indirect measurement techniques.

2. Material absorption values

The absorption of laser light by a material depends on a number of important properties of the material, such as absorption rate, reflectivity, thermal conductivity, melting temperature and evaporation temperature, the most important of which is the absorption rate.

The factors affecting the absorption rate of a material to a laser beam include two aspects: one is the resistivity of the material. After measuring the absorbance of the polished surface of the material, it was found that the absorbance of the material is proportional to the square root of the resistivity, which varies with temperature. and changes; secondly, the surface condition (or finish) of the material has a more important effect on the beam absorbance, which has a significant impact on the welding result.

The output wavelength of a CO2 laser is typically 10.6 μm. Non-metals such as ceramics, glass, rubber and plastics have a high absorption rate at room temperature, while metallic materials have a poor absorption rate at room temperature until the material melts or even outgasses. Its absorption only increases sharply. The use of surface coatings or the generation of oxide films on the surface is very effective in increasing the absorption of the beam by the material.

3. Pulse shape and width

The pulse waveform is an important issue in welding, especially for thin plate welding. When a high intensity beam strikes the surface of a material, some of the energy from the metal surface is lost by reflection, which varies with the surface temperature. The reflectivity of the metal varies considerably during the pulse action.

Pulse width is one of the important parameters of pulse welding. It is not only an important parameter that differs from material removal and material melting, but is also a key parameter in determining the cost and size of the processing equipment.

4. The effect of defocusing

Due to the high power density in the centre of the spot at the laser focal point, it tends to evaporate into a hole. In each plane away from the laser focal point, the power density is more evenly distributed. There are two methods of defocusing: positive defocusing and negative defocusing. If the focal plane is above the workpiece, it is positively defocused, otherwise it is negatively defocused. According to geometrical optics theory, when the distance between the positive and negative defocus plane and the welding plane is equal, the power density on the corresponding plane is approximately the same, but the actual shape of the molten pool obtained is different. When the defocusing is negative, a greater penetration depth is obtained, which is related to the formation process of the molten pool.

Steps in the operation of the laser welding machine

Preparation before starting

1. Check that the laser welding machine power connection is intact and that the water circulation is normal.

2, check whether the machine equipment gas circuit connection is normal.

3, check that the machine surface is free of dust, spots, oil, etc.

4、Before starting the machine, turn on the power supply of the automatic table and other motion control parts, check whether the parts are running normally, and then turn on the computer under normal conditions.

Turn on the machine

1、Turn on the power supply and open the main power switch.

2、Open the water cooler, laser generator, etc. in turn.

3、Open the argon valve and adjust the gas flow.

4. enter the current working parameters to be performed.

5. carry out the welding operation.

Switch off

1. exit the program and switch off the laser generator.

2. turning off the dust collector, water cooler and other equipment in sequence.

3. closing the argon gas cylinder valve.

4. switch off the main power switch.

In other words, the operator should be aware of the process and procedures when operating the laser welding machine and be able to commission it in a specific way. Special requirements of the material or differences in the welding process may cause the machine to operate improperly. Only in this way can the laser welding machine maintain good processing results and bring us efficient, standardised production.