The printing machine (50) comprises a central impression drum (35) supporting a web substrate (S), several printing groups (51-55) arranged around an entry side (35a) and several printing groups (56-60) arranged around an exit side (35b) of the central impression drum for applying water-based inks or solvent-based inks on the web substrate (S), and at least one drying unit (61-69) arranged between each pair of adjacent printing groups. The first drying unit located in a larger space between the first printing group (51) and the subsequent printing group (53) and/or the last drying unit located in a larger space between the last printing group (60) and the preceding printing group (58) is an extensive drying unit (61, 69) providing an exposure time to a drying agent longer than the remaining drying units.