Matching your spindle rpm to the torque peak and then trying to maximize feedrate is an interesting problem, particularly when you deal with both chip thinning and an HSM constant engagement (Volumill) toolpath.
It's pretty easy to play with the numbers in G-Wizard. I just typed in a 2000 rpm limit which forced it to stay there or below and then ran the 5/8" cutter at the described 1.5" depth and 0.035" width of cut.
I get 111 IPM feed at 2000 rpm for the HSM toolpath. Pretty crazy fast, but remember, the HSM path really unshrouds the cutter so it can stay cool and clear the chips. The open question is whether we can hold down the rpms that much and still have the cutter be happy--I haven't seen much real world data to say and G-Wizard is calibrated to reported successful feeds and speeds.
Another thing to consider is that cut is showing about 1.2 HP. Even though you're at your torque peak, seems like we're scrimping a little on horsepower. In other words, it's topping out on the projected max chipload before really harnessing your torque peak.
If we try 3000 rpm, it shows 167 IPM and 1.8 HP which is a bit better. I think I'd try more like that range. If you want to be conservating, start at
about 85 IPM and work up to 167.
Best,
BW
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