Why use ultrasonic welding and how does it work?
Why use ultrasonic welding?
Ultrasonic welding is used for the assembly of thermoplastic material or the assembly of nonthermoplastic material to thermoplastic material by means of insertion or staking. The process is a much faster and safer alternative to using solvents or heat as a bonding method. Ultrasonic welding is used by automotive, medical, toy and many other product manufacturers that use plastic for their product material.
How does ultrasonic welding work?
Ultrasonic welding is the conversion of high-frequency electrical energy to high-frequency mechanical energy. This mechanical energy is a vertical motion in excess of 15,000 cycles per second. When this vertical, vibrating motion is transferred to a thermoplastic material under pressure, frictional heat is generated at the interface, or joints, of two pieces of thermoplastic or with a metal and thermoplastic. This conversion process is done through an ultrasonic welder properly tooled with a horn and fixture. (See top illustration) The welder’s power supply converts standard 60 hz alternating current to frequencies of 15,000 hz, 20,000 hz, or 40,000 hz, depending on which welder you own. This alternating current enters the convertor where it is converted to vertical, mechanical motion equal to the alternating current – 15,000, 20,000 or 40,000 vertical cycles per second. This vertical motion comes out the other end of the converter, passes through a booster which can increase the amplitude of the vibrating motion, and is then passed to the horn which transfers the mechanical energy to the parts that are being welded. The parts that are being welded are secured in a fixture which holds the parts in place and square to the horn. This is just a brief overview of the ultrasonic welding process. Many variables in amplitude, weld time, pressure, horn design, fixture design and joint design need to be considered in order to achieve successful plastic assembly. Toman Tool Corporation’s engineers have over 50 years of combined experience in working with these plastic assembly challenges. They are always eager to find solutions to new plastic assembly applications.