Joint Design Guidelines Used in Ultrasonic Welding
The most critical factor of part design for ultrasonic welding is the joint design, or the configuration, of the two mating surfaces. It should be considered while the parts to be welded are still in the design stage and then be incorporated into the molded parts.
There are a variety of joint designs, each with specific features and advantages. Their selection is determined by such factors as type of plastic, part geometry, weld requirements, machining and molding capabilities, and cosmetic appearance.
The four main joint designs are Butt, Step, Shear, and Tongue and Groove. The illustrations below show an example of each one of these joints. Notice the placement of the energy director, or the triangularly shaped ridge molded into one of the mating plastic parts. This ridge limits initial contact to a very small area. The ridge melts during ultrasonics causing plastic to flow through the joint and bond the parts together.
There are many variations of each of these four joint designs. Toman can assist you in determining the proper joint design for your welding application.
Contact Toman ThermoSonics for any questions regarding ultrasonic welding joint design guidelines.