Systems and methods using an ultrasonic transducer and scrubbing horn motion to seal a part

An ultrasonic welding system having an ultrasonic transducer assembly, the system comprising:

• an ultrasonic transducer assembly including a horn and a first transducer arranged to impart ultrasonic energy into the horn, the horn having a first part-interfacing surface at an exposed edge extending along a length of the horn and configured to contact a part to be joined, and a second surface along an opposite exposed edge extending along the length, wherein the height is a distance between the exposed edge and the opposite exposed edge;
• wherein the horn has a height corresponding to an integer multiple of one wavelength, λ, of the applied ultrasonic energy, and includes at least two nodes and at least two anti-nodes, wherein the at least two nodes are areas or regions of the horn of minimal amplitude of the ultrasonic energy and maximal mechanical strain of the horn, and wherein the at least two anti-nodes are areas or regions of the horn of maximal amplitude and minimal mechanical strain, wherein a first of the at least two nodes is arranged at about λ/4 from the first part-interfacing surface, and a second of the at least two nodes is arranged at about λ/4 from the second surface, and wherein a first of the at least two anti-nodes is proximate the first part-interfacing surface, and a second of the at least two anti-nodes is proximate the second surface;
• one or more controllers operatively coupled to the ultrasonic transducer assembly and to the actuator assembly, the one or more controllers operatively being configured to:
• cause the first transducer to impart the ultrasonic energy directly or indirectly via one or more boosters into the horn to cause the first part-interfacing surface to vibrate back and forth along the length in a direction transverse to the height.