Originally Posted by
TTalma
I've got my machine running pretty good. Last night a loaded a new setup. This involved using a metalworking dovetail tool. The tool has 12 flutes on it. So to prevent burning in hard maple I ran the spindle at 5000 rpm, machine at 100ipm.
I got a nice finish with no burning. But after running for about 10 min the VFD errored and shut down. Fortunately the machine was moving (not cutting) and I was able to e-stop before any damage.
I checked the code on the VFD and if shut down due to over heating. I felt the heatsink and it was to hot to touch. I shut the system down and let everything cool off. I loaded a new part and same thing happened.
After cooling off I switched tools and jobs I was running a 3/4" 2 flute at 18000 rpm 100ipm bit for about 45 min. I felt the VFD and it was warm, not hot.
So I switched back to the job with the 12 flute bit. I changed the speed to 10000 rpm 200 ipm, got a nice surface finsih etc. and the machine finished the job (about 15 min). I felt the VFD and it was real hot. I think it would have overheated if I had run it longer.
During everything the spindle got pretty warm, but never what I would consider hot.
The only thing I could figure from the over heating was that the VFD had to work extra hard because of the 12 flute bit to keep the spindle at speed. But I couldn't wrap my head around that since I don't have speed feedback from the spindle.
So why would the VFD overheat?