Ultrasonic welding is an industrial process where electrical energy is converted into mechanical vibration.
High frequency (ultrasonic) sound waves, called acoustic vibrations, and transmitted through a plastic part (held together under pressure) to the joint interface. These ultrasonic vibrations create friction and locally heat the joint area causing the parts to become welded together. No other consumables are required. The two parts are ultrasonically welded to each other. The process is extremely fast (cycle times generally within 1 second) and very energy efficient.
For assembly of complex thermoplastic moulded parts, ultrasonic welding equipment can easily be applied to join parts by welding. Strong structural welding can easily be achieved. Ultrasonic tooling is customised to fit the exact specifications of the parts being welded. Plastic parts are sandwiched between a customised fixed nest (anvil) and the work horn (sonotrode). Common ultrasonic welders operate at frequencies between 20 kHz to 70 kHz. Often the joint interface can require a special ‘joint design’ to assist the melt and flow of the plastics. The ultrasonic energy melts the contact points of the parts, creating a weld.
Ultrasonics can also be used to weld metals. Ultrasonic metal welding is generally limited to thin ‘white metals’ in applications such as ‘wire splicing’, ‘spot welding’ and sealing of copper tubes. Ultrasonic Weldable metals include: aluminum, copper, nickel.
Ultrasonic welding of thermoplastics causes local melting of the plastic due to absorption of vibrational energy along the joint line. In metals, welding occurs due to high-pressure dispersion of surface oxides and local motion of the materials.
The benefits of ultrasonic welding:
Ultrasonic welding is very fast and very energy efficient. No consumables (adhesives or solvents) are required. Ultrasonic welding can be automated by easy integration into exisiting packaging lines, or handling and manipulation by multi axis robotics.