The heaviest sentence was given to Jackson Lopez Trivino, while José Ernesto Rose Martinez got 14 years and Andrea Lopaz Barraza was sentenced to 11 years and four months, Corriere reported.
The three were convicted on charges of attempted murder.
Three others were acquitted by the Milan court for their involvement in the attack at Villapizzone train station, in the city's outskirts, last June.
Train conductor Carlo Di Napoli almost lost an arm in the attack, while Riccardo Magagnin, an off-duty railway worker who intervened to help his colleague, suffered a blow to the head that left him with cranial trauma.
Judge Alfonso Ferrara also ruled compensation for the two men.