Introduction to Ultrasonic Brazing Welding Method

Introduction to Ultrasonic Brazing Welding Method – Sonic4Lab

In modern industrial manufacturing, firmly and precisely connecting two materials together is a key process. For many conventional metals, traditional welding or brazing techniques are already very mature. However, when faced with aluminum alloys, stainless steel, and even ceramics and composite materials, the dense oxide film on the surface of these materials becomes a huge obstacle, which can prevent the normal spreading and bonding of brazing materials. At this point, an advanced brazing technology that utilizes ultrasonic energy for assistance – ultrasonic brazing, has demonstrated its unique advantages.

Origin and Development of Technology

The concept of ultrasonic brazing technology is not a new thing. As early as the late 1930s, early patents for using ultrasonic waves for metal welding appeared overseas. In the 1950s and 1960s, with the increasing application of aluminum alloys and stainless steel in industry, it became particularly urgent to solve the brazing problem caused by their surface oxide films, which led to the widespread research and attention of ultrasonic brazing technology. To this day, this technology has not only been successfully applied to the above-mentioned metals, but also extended to the field of connecting new materials such as ceramics and composite materials, solving many challenges that conventional methods cannot cope with.

Core technical principle: Ultrasonic and cavitation effects

The secret of ultrasonic brazing does not lie in directly heating the workpiece with ultrasonic waves. The process usually involves heating the workpiece and brazing material through other means such as soldering iron, heating table, etc., until the brazing material melts and forms a liquid state, and then introducing the vibration energy of ultrasonic waves into the melted brazing material.

The most critical mechanism among them is the ‘cavitation effect’. We can understand it as follows: when high-frequency ultrasound propagates in liquid solder, it forms alternating compression and sparsity regions like sound waves in water. In the sparse (stretching) stage, the liquid will be torn apart, producing tiny bubble nuclei; The subsequent compression stage will cause these bubbles to rapidly expand and suddenly collapse, and this instantaneous process is called “cavitation”.

Do not underestimate the rupture of this microscopic bubble. Within a very short period of its collapse, the surrounding micro regions will generate extremely astonishing local high temperature and high pressure shock waves (theoretically instantaneous temperatures can reach thousands of degrees Celsius, and pressures can reach tens of megapascals). It is this powerful force that can effectively impact, tear, and remove the oxide film on the surface of the base material, exposing the pure active metal surface. In this way, the liquid brazing material can smoothly wet the base material and achieve a strong metallurgical bond. Due to the fact that ultrasound can complete the task of “cleaning” surfaces on its own, in many cases, ultrasonic brazing can no longer rely on traditional fluxes.

The significant characteristics of ultrasonic brazing

1. Suitable for low-temperature brazing: This technology is particularly suitable for use at relatively low temperatures (usually referring to the range of soft brazing). Because excessively high temperatures can exacerbate the impact of cavitation on the liquid solder material itself, which may cause solder splashing or a decrease in welding quality, the general application temperature should not exceed 400 ℃.

2. No need or reduced use of flux: This is one of the most prominent advantages of ultrasonic brazing. Traditional brazing relies on flux to chemically remove oxide films, while ultrasound achieves this goal through physical means, simplifying the process and avoiding potential corrosion issues caused by flux residue.

3. Environmental Protection and Cleanliness: Due to the avoidance of the use of flux, harmful smoke caused by the volatilization of flux will not be generated during the heating process. At the same time, the requirement for cleaning the metal surface before welding is also reduced, reducing the dependence on chemical cleaning agents such as strong acids and alkalis, which is more in line with the concept of green manufacturing.

In summary, ultrasonic brazing is an efficient and clean precision connection technology that cleverly utilizes the energy of sound waves to solve key bottleneck problems in material connections. With the continuous emergence of new materials, this technology will play an increasingly important role in the high-end manufacturing field.

If you want to purchase equipment, please click here