A continuous filament additive manufacturing machine for building a part by laying down a continuous mono-filament or composite filament material layer by layer on a tool or substrate. The machine includes a system, such as a robot, operable to move in at least three degrees of freedom, and a placement module coupled to the system and being configured to deposit the continuous filament material. The placement module includes a guide for guiding the material to the part, an ultrasonic compaction device including an ultrasonic driver, an attachment frame and an ultrasonic disk horn coupled to the attachment frame. The ultrasonic driver is coupled to the disk horn and ultrasonically vibrates the horn in a reciprocating manner to melt or flow the material and cause the material to fuse and be compacted to the tool or substrate.