What is Ultrasonic Welding?

Ultrasonic welding represents a highly innovative joining technique that harnesses the power of high-frequency vibration waves. These waves are precisely directed towards the surfaces of two objects slated for welding. When pressure is concurrently applied, a fascinating process unfolds. The surfaces of the objects engage in a vigorous rubbing action, which, at a microscopic level, prompts the fusion of molecular layers, effectively bonding the two materials together.

This process begins with an ultrasonic generator, a crucial piece of equipment that transforms the standard 50/60 Hz electrical current into high-frequency energy, typically in the range of 15, 20, 30 or 40 KHz. The newly converted high-frequency electrical energy then passes through a transducer, which performs a remarkable feat by converting it once again, this time into mechanical motion of the exact same frequency. This mechanical motion is then channeled through a specialized device known as a booster. The booster, with its unique capacity to modulate amplitude, ensures that the motion is optimized before reaching the welding tip. The welding tip, as the final conduit, relays the received vibration energy to the joint area of the workpieces awaiting welding. In this critical zone, the vibration energy undergoes a transformation, being converted into heat energy through the mechanism of friction. This generated heat is sufficient to melt the metal, facilitating a seamless weld.

The main constituents of an ultrasonic welding system are quite comprehensive. It encompasses an ultrasonic generator, which serves as the power source and frequency converter; a transducer/booster/welding tip assembly, each component playing a vital and interconnected role in the energy transfer and modulation process; molds, which provide the necessary shaping and support; and a frame, offering structural integrity and stability. As visually depicted in the following figure:

Principle of Ultrasonic Metal Welding

The principle underlying ultrasonic metal welding is a truly distinctive and specialized approach. It capitalizes on the mechanical vibration energy of ultrasonic frequencies, specifically those exceeding 16 KHz, to establish connections between metals, be they of the same or different types. What sets this method apart is its unique operating mode. When engaged in ultrasonic metal welding, there is no need to supply current to the workpieces, nor is a high-temperature external heat source required. Instead, under the influence of static pressure, the wire-frame vibration energy is cleverly harnessed and converted. It morphs into friction work, generating the necessary heat at the interface of the workpieces, as well as deformation energy that helps in shaping and bonding, along with a limited yet controlled temperature rise. This metallurgical bond that forms between the joints is a remarkable achievement, as it represents a solid-state welding process. In other words, the base metal remains intact, without undergoing melting, effectively circumventing issues like spatter and oxidation that are commonly associated with traditional resistance welding. Ultrasonic metal welding machines have demonstrated their versatility by being capable of performing single-point welding, multi-point welding, and short-strip welding on fine wires or thin sheets of non-ferrous metals such as copper, silver, aluminum, and nickel.

This welding modality offers two standout advantages: an extremely short welding time, which boosts productivity and reduces production cycles, and high cost-effectiveness, making it an economically viable option for many industrial applications.

Advantages and Disadvantages of Ultrasonic Metal Welding

The benefits of ultrasonic metal welding are both numerous and significant. Firstly, its speed is a major asset. The rapidity with which it can complete a weld is a boon for high-volume production lines, allowing for faster turnaround times. Secondly, it is an energy-efficient process, consuming considerably less power compared to some of its counterparts, which is not only environmentally friendly but also cost-effective in the long run. The high fusion strength it imparts ensures that the welded joints are robust and reliable, capable of withstanding various mechanical stresses. Good electrical conductivity is another plus, making it suitable for applications where electrical flow is crucial.

The absence of spark generation adds an element of safety, especially in environments where flammable materials may be present. Moreover, its near-cold processing nature means that it minimizes heat-induced distortions and alterations to the base materials, preserving their original properties.

However, like any technology, it does have its limitations. One of the primary drawbacks is that the welded metal parts cannot be overly thick. Generally, the thickness is restricted to 5 mm or less, which can pose a constraint for certain applications where thicker materials are required. Additionally, the size of the welding spots is also limited. Larger areas cannot be effectively welded in a single pass, necessitating multiple operations or alternative techniques. Pressure application is another requisite, which means that appropriate equipment and control mechanisms need to be in place to ensure the correct amount of pressure is exerted throughout the welding process.

Despite these limitations, ultrasonic metal welding remains a highly valuable process. It is a mechanical processing marvel, as during the welding process, no current courses through the welded parts, and there is no formation of a welding arc akin to that seen in electric welding. This absence of current and arc eliminates concerns related to heat conduction and resistivity, making it an ideal choice for non-ferrous metal materials. It has proven its efficacy in welding sheet materials of diverse thicknesses, adapting to the varying needs of different manufacturing scenarios.

Focusing on Metal Connection Technologies

In the realm of metal connection technologies, a team of automotive product R & D experts, armed with advanced knowledge and proficiency in ultrasonic welding, has been making remarkable strides. They have painstakingly developed connection pairing technologies, which are firmly rooted in relevant automotive standards and meticulously tailored to meet customer requirements. Through a series of rigorous and repeated verifications, these technologies have effectively mitigated the technical drawbacks associated with ultrasonic welding. Concurrently, within the production process, an efficient quality inspection system has been instituted. This system operates with precision and vigilance, ensuring that the products emerging from the production line boast excellent performance indicators, meeting and often exceeding the expectations of the market.