I'm new to CNC. Recently I was trying to machine a 1mm, 120mm long with DOC of 0.5mm with a 1mm end mill. I'm running this on a 3-axis VMC.

Tool: 1mm carbide 4 flutes with TiSiN coating (claimed by the seller)
Material: Mild steel

First trial: 3500rpm, 15mm/min and the tool broke halfway. Inspected the end mill and it seems like the speed is too high causing the tool to heat up, the end appears dark and burnt.

Second trial: 2000rpm at 20mm/min, tool looks OK when I paused the machine to inspect but still broke.

Coolant was used on both trials.

I've used G-Wizard to get an idea on the speed and feed, it says that my chip load is too low and may cause rubbing, maybe this is the culprit? or I'm just not dialing the speed and feed correctly.

Thanks