Methods and systems for no-glue pocketed spring unit construction. Rows of pocketed springs, preferably arranged into modules (200) of more than two pocketed springs surrounding a central hole (104), are ultrasonically welded together when paired vibrating probes (110) and anvils (112) press layers of pocketed spring fabric from the rows of pocketed springs together and a welding pulse is transmitted to the vibrating probe (110).