Since the first laser beam invented by scientists in 1960, people have used laser processing as scientific productivity. In recent years, due to the characteristics of flexible processing and improving production efficiency, laser processing technology has been widely used in industrial fields. Laser welding is an efficient and precise welding method that uses a high-energy density laser beam as a heat source. Together with laser cutting and laser marking, it constitutes the “troika” of laser processing technology.
However, compared with laser cutting and laser marking, the development time of laser soldering is relatively short, and the process is more difficult. Among them, the problem that affects the spot welding quality of the laser soldering machine has become a concern of current customers when purchasing laser soldering equipment. The editor believes that the main factors are welding current and energizing time, electrode pressure and shunting.
- 1. Welding current and power-on time. According to the size of welding current and the length of energizing time, spot welding can be divided into two types: hard specification and soft specification. The specification for passing large current in a relatively short period of time is called the hard specification. It has the advantages of high productivity, long electrode life, and small deformation of the weldment. It is suitable for welding metals with good thermal conductivity. The specification that passes a smaller current for a longer period of time is called a soft specification, and its productivity is low, and it is suitable for welding metals that have a tendency to harden.
- 2. Electrode pressure. During spot welding, the pressure exerted on the weldment by the electrode is called the electrode pressure. The electrode pressure should be selected appropriately. When the pressure is high, the shrinkage porosity and shrinkage holes that may be generated during the solidification of the nugget can be eliminated, but the resistance and current density of the connection system are reduced, resulting in insufficient heating of the weldment, and the diameter of the weld nugget is reduced. The solder joint strength decreases. The size of the electrode pressure can be selected according to the following factors: (1) The material of the weldment. The higher the high temperature strength of the material. The greater the electrode pressure required. Therefore, when welding stainless steel and heat-resistant steel, a higher electrode pressure should be used than welding low-carbon steel. (2) Welding parameters. The harder the welding specification, the greater the electrode pressure.
- 3. Diversion. During spot welding, the current flowing from outside the main welding circuit is called shunt. The shunt reduces the current flowing through the welding area, resulting in insufficient heating, resulting in a significant decrease in the strength of the solder joint, and affecting the welding quality.
The factors affecting the degree of diversion mainly include the following aspects:
- (1) The thickness of the weldment and the distance between the weld points. As the distance between solder joints increases, the shunt resistance increases and the degree of shunt decreases. When the conventional dot pitch of 30-50 mm is used, the shunt current accounts for 25%-40% of the total current, and as the thickness of the weldment decreases, the degree of shunting also decreases.
- (2) The surface condition of the weldment. When there are oxides or dirt on the surface of the weldment, the contact resistance between the two weldments increases, and the current passing through the welding zone decreases, that is, the degree of shunting increases. The workpiece can be pickled, sandblasted or polished.
Wonder Inc is the leading provider of china laser cutting solutions and has been advancing the application of laser technology since 1995. Research and Development efforts have resulted in numerous patents, with several pending, in our continual pursuit to develop and enhance laser systems that benefit the customer. Our R&D philosophy and execution are based upon designing highly modular solutions which gives customers the flexibility and investment protection to optimize laser systems as their business evolves.