A partially foam encased pocketed spring assembly is made in a fully automated assembly machine. A first foam rail is introduced into the assembly machine and glued to upper and lower substrate webs. A first string of pocketed springs is then glued to a side surface of the first foam rail between upper and lower substrate webs and glued to the upper and lower substrate webs. Additional strings are joined together to create a pocketed spring interior. A second foam rail is then introduced into the assembly machine and glued to an outer string and to the upper and lower substrate webs to create a core. Third and fourth foam rails are glued to the core.