Anyone experienced hard milling a material like C45? I am having troubles with a new job in shop. Simply a part has more milling process rather than turning. Using 8 mm solid carbide chatter free iscar endmills. 3 mm depth of cut generally. Doing side mills also. I prefered doing down milling coz the mill was chattering a lot in up milling. I am also using a long guide bush to make the part stable enough. 2500 rpms and 450-500 mm/min feed for roughing and 3500 rpms and 600-800 mm/min feed for finishing applications. The guys here telling me to give more rpms and feed :nono:- i tried to give a little more but chattering problems began - but swiss machines are not that stable like vertical milling machines! Is there anything wrong with it? Or am i just havin a brain fart? I am trying to optimize the tool life and cycle time..The part has 12 mm of diameter and with 60 mm length. And i cannot do a sync with sub spindle because of the part's geometry. The machine is 20mm hanwha. Any ideas for a better tool life?