Ultrasonic metal welding is a solid-state welding process that uses localized high-frequency vibratory energy in conjunction with moderate clamping force. It does not require consumables — such as welding rods, fluxes, fillers, or solders — or special cleaning methods. This energy-efficient, environmentally-friendly system produces no arcs or sparks. It is excellent for joining non-ferrous dissimilar metals, for welding thin sections to thicker sections, for joining multiple layers of thin materials, and for welding through most oxides and surface oils. Ultrasonic metal welding produces strong joints that have good thermal and electrical conductivity. Only a modest amount of space is needed for the equipment.

The advantages of ultrasonic metal welding are particularly noteworthy in the assembly of wire harnesses for automotive and similar applications. Resistance welders need 20 times more energy than ultrasonic welders. They may also require water cooling, which can be both costly and necessitate treatment of the water before it can be returned to the water supply. Yet it only takes about the same amount of time to make an ultrasonic weld as it does to produce a resistance weld. Wire harness manufacturers also report that ultrasonic welding reduces the expense of attaching copper wires by 50 percent over old crimp and solder methods. In addition, ultrasonically welded joints are stronger, have better electrical conductivity, and weigh less without the mechanical crimp.

Wedge-Reed Design
After proudly pointing out that Sonobond's ultrasonic metal welders are all manufactured in the U.S.A., Sonobond President Janet Devine went on to cite several other factors that help make this technology such an excellent choice. She said, "We design our equipment in ways that help manufacturers reduce costs. For instance, Sonobond machines are easy to operate and require only minimal training. Our microprocessor-controlled ultrasonic welders can set and recall up to 250 weld protocols from memory. Welding can be controlled by height, energy or time. All this substantially reduces the possibility of costly mistakes on the part of machine operators."

PV tip over panel solar cell assembly being ultrasonically welded.

Devine continued, "There are also built-in features that provide meaningful savings to our customers. For example, all Sonobond metal spot welders use the patented Wedge-Reed System that combines high vibratory force with low amplitude coupling for maximum metal welding effectiveness. This system uses heat-treated, tool steel Taper Lock Tips that are manufactured to last for up to 100,000 welds. When the tips finally do need to be replaced, this can be done quickly and easily on our machines. However, ultrasonic metal welders manufactured by some other companies may require replacement of the entire horn, not just the tip. This can be much more expensive in terms of downtime and labor costs. But that's not all. Only the Sonobond ultrasonic system is capable of welding most oxidized and tinned metals. This is another important reason so many companies specify Sonobond equipment."

Many Applications
During her long career at Sonobond, Janet Devine has played a critical role in overseeing the development of ultrasonic metal welders for a wide variety of uses. These applications include:

• Assembly of wire harnesses and heavy-duty cables for cars, trucks, and industrial machinery. Sonobond equipment can weld wire bundles with cross-sectional areas of up to 100mm², even with lightly tinned or oxidized wires. It is unique in its ability to accomplish this with a single pulse.
  
• Advanced battery and super capacitor applications involving up to 80 layers of foils even if lightly tinned. The dual-head system can also weld 3 millimeter-thick, non-ferrous sheet metal when equipped with appropriate tooling.
  
• Assembly of the solar cells that constitute solar panels. Sonobond equipment can be used for welding aluminum strips to the metalized glass on PV modules. The resulting interconnects between the PV cells create an array with excellent conductivity.
  
• Welding of larger metal parts, such as those used in the automotive industry. The "C-frame" units virtually eliminate the problem of tips sticking to aluminum parts and can be equipped for use on large industrial robots.
  
• Spot welding — including wire-to-terminal welding — in a single pulse. Sonobond ultrasonic metal welders are ideal for bus bar fabrication, as well as for welding stranded wire to brass or copper terminals and producing single point ground terminals.
  
• Fast, clean splicing of thin aluminum and copper foils up to 0.004-in. (0.1mm) thick and up to 48-in. (1.2m) wide. Our system consists of a power unit with a solid-state converter, a welding head, and a rotating disk tip which transverses the width of the foil at speeds up to 15 feet per minute. This technology is found in practically all U.S. foil mills.
  
• The industry's most powerful spot welder with a full 4,500 watts of output for welding heavy gage wire to terminals, ignition module plates, and other electronic/electrical assemblies. The welded joints are often stronger than the parent metals, and the process usually takes less than 1.5 seconds.
  
• Portable, hand-guided tube closure for precisely crimping and sealing copper and aluminum tubing. This one-step process creates quick, airtight seals without brazing and can accommodate tubes already charged with coolant, fluids, and gasses.

Decades of Growth
Ultrasonic metal welding has gained acceptance — and even a certain amount of prestige — over the decades. Time and time again, manufacturers across a wide variety of fields have found this process to be an extremely cost-effective and reliable solution to their needs. Sonobond has played an important part in finding new applications in evolving industries. These include significant innovations in the EV vehicle, solar, battery, electrical, and cable industries. At the same time, the company's equipment continues to improve in terms of power capacity, reliability, and better control functions.

Although recent economic conditions have kept some companies from investing in new equipment, Ms. Devine believes there will be pent-up demand as things improve. She says, "We see more applications for ultrasonic welding and a greater acceptance of its use in a range of niche industries. We also anticipate that robotics will mean increased utilization of ultrasonics for welding aluminum and other lightweight sheet metals. This is especially true among automotive and battery manufacturers. Sonobond is very optimistic about the future of ultrasonic metal welding and firmly committed to maintaining its leadership role in this growing field."

In addition to its complete line of ultrasonic metal welders, Sonobond offers ultrasonic equipment for nonwovens/textile and plastic applications. Among the company's many customers are leading firms in the electrical, automotive, appliance, solar, aerospace, filtration, and apparel industries.